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Mechanistic Hypotheses

1

Canonical GALC Deficiency / Psychosine-Mediated Demyelination Model

canonical_galc_deficiency_psychosine_demyelination_model CANONICAL

Evidence balance 3 support 2 refute

Krabbe disease (globoid cell leukodystrophy) is an autosomal recessive lysosomal storage disorder caused by loss-of-function variants in GALC encoding galactocerebrosidase. Loss of GALC activity prevents lysosomal hydrolysis of galactosylceramide but, critically, also fails to clear its toxic deacylated lyso-derivative galactosylsphingosine (psychosine). Psychosine accumulation in oligodendrocytes and Schwann cells triggers apoptosis of myelin-forming cells, secondary lipid-laden multinucleated macrophages (globoid cells), and progressive CNS and peripheral demyelination. The infantile form (~85% of cases) presents in the first 6 months with irritability, hypertonia, opisthotonus, seizures, blindness, and death by age 2-3 in untreated patients. Pre-symptomatic hematopoietic stem cell transplantation (the only available disease-modifying therapy), the twitcher mouse model (Galc^trs/trs) faithfully recapitulating the human phenotype, and AAV-GALC gene therapy corroborate the GALC-deficiency / psychosine-toxicity / demyelination axis as the canonical pathogenic mechanism.

Retained as CANONICAL with required expansion to multi-mechanism framework. The 2026 openscientist hypothesis-search report (kb/hypotheses/Krabbe_Disease/canonical_galc_deficiency_psychosine_demyelination_model) finds SUPPORTED with significant qualifications. The core GALC-deficiency → psychosine-accumulation → demyelination cascade is quantitatively validated: residual GALC activity across 31 missense variants correlates with age of onset (Pearson r > 0.94); acid ceramidase ablation in twitcher mice eliminates psychosine and reportedly CURES GLD; gene therapy (AAV-GALC) corrects metabolism and extends survival in mouse and canine models; psychosine is validated as a newborn-screening biomarker. Critical refinement: PSYCHOSINE IS NECESSARY BUT NOT SUFFICIENT — (1) saposin-D ablation in twitcher mice eliminates psychosine accumulation yet fails to prevent late-stage demyelination (and even shortens lifespan); (2) a UGT8 inhibitor reduces psychosine by 72–86% without extending lifespan. The canonical model must expand to incorporate parallel/downstream mechanisms: (a) galactosylceramide-driven globoid-cell macrophage pathology; (b) neuroinflammation including adaptive immunity; (c) cell-autonomous neuronal dysfunction (not just oligodendrocyte/Schwann-cell death); (d) autophagy dysregulation; (e) UPR / ER stress; (f) emerging α-synuclein aggregation and sphingolipid fibril formation. GALC has critical functions beyond psychosine degradation. Pre-symptomatic HSCT remains the only disease-modifying therapy and validates the upstream GALC axis even though it does not fully prevent downstream cell-autonomous and inflammatory cascades.

Deep research

OpenScientist citations 33 citations 2026-05-24T16:48:56.316286

Show evidence (5 references)

PMID:31527255 SUPPORT Other

"Infantile globoid cell leukodystrophy (GLD, Krabbe disease) is a fatal"

Existing canonical mechanism citation in the dismech knowledge base, used as the seed for the hypothesis-search deep-research run.

PMID:40449593 SUPPORT In Vitro

"residual GALC activity strongly correlated with the age of disease-onset in reported cases (Pearson's r > 0.94, p < 0.0001), suggesting that enzyme activity resulting from MMV expression in this model may serve as a readout for clinical prognostication"

Supplies the quantitative dose-response that this entry's notes previously asserted without a citation. A panel of 31 GALC missense variants expressed in a GALC-knockout human oligodendrocytic line ties residual enzyme activity to reported age of onset. The correlation is against onset ages taken from published case reports rather than a prospective cohort.

PMID:40449593 SUPPORT In Vitro

"we observed an inverse correlation between residual GALC activity and endogenous psychosine levels in the MMV panel"

Completes the dose-response chain the hypothesis asserts, linking the degree of residual enzyme activity to the amount of psychosine that accumulates in the same human cellular model.

+ 2 more references

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Discussions and Knowledge Gaps

2

Why do three independent ways of removing psychosine from the twitcher mouse give three different outcomes, and which non-psychosine product of GALC activity accounts for the demyelination that survives psychosine elimination?

KNOWLEDGE GAP OPEN gap_krabbe_psychosine_depletion_discordance

Attached to

mechanistic_hypotheses#canonical_galc_deficiency_psychosine_demyelination_model pathophysiology#Psychosine Accumulation pathophysiology#Demyelination pathophysiology#GalCer-Driven Macrophage Pathology

Acid ceramidase ablation eliminates psychosine and rescues the twitcher phenotype, but saposin-D ablation also eliminates psychosine while leaving late-stage demyelination intact and shortening lifespan, and a UGT8 inhibitor cuts psychosine 72-86% without changing survival. The three results cannot all be explained by psychosine being the operative toxin, so the sufficiency half of the canonical model is unsettled even though its upstream half is quantitatively validated. This is not a bookkeeping detail: whether a psychosine-lowering drug can work as monotherapy depends on the answer, and substrate reduction therapy is already curated in this entry as an investigational strategy aimed at psychosine biogenesis. No head-to-head comparison of the two knockout crosses exists; the three studies used different genetic backgrounds, endpoints, and time points, so the discordance may be partly methodological.

Proposed experiments

Matched-background lipidomic comparison of psychosine-null twitcher crosses

comparative mass-spectrometry lipidomics of matched mouse crosses

exp_krabbe_matched_background_sphingolipidomic_comparison

Generate ACDase-knockout and saposin-D-knockout twitcher crosses on one congenic background and profile brain, spinal cord, and sciatic nerve at matched pre-symptomatic, early, and late time points. Quantify the full sphingolipid panel, not psychosine alone, so that species differing between a rescued and an unrescued psychosine-null animal can be identified. Score demyelination, globoid cell burden, and survival in the same animals.

Decision criterion

A non-psychosine lipid that tracks with rescue across the two crosses nominates the missing toxic species and would justify a distinct pathophysiology node. If the two crosses are lipidomically indistinguishable, the discordance is not metabolic and attention should move to the macrophage and saposin-D-dependent arms.

Would support

pathophysiology#GalCer-Driven Macrophage Pathology

Supporting outcome

Galactosylceramide or another GALC substrate remains elevated in the unrescued psychosine-null cross and tracks with globoid cell burden and demyelination severity.

Refuting outcome

Both psychosine-null crosses show the same lipid profile and the same demyelination, which would place the difference outside sphingolipid metabolism altogether.

Show evidence (2 references)

PMID:37337846 SUPPORT Model Organism

"The demyelination observed in Twi/Sap-D KO mice may be mediated by a psychosine-independent, Sap-D-dependent mechanism"

The authors state the gap in their own terms: a psychosine-independent mechanism is required to account for the demyelination they observe, and they do not identify it.

PMID:35290889 SUPPORT Model Organism

"Administration of RA 5557, reduced pathologically elevated psychosine concentrations (72-86%) in the midbrain and cerebral cortex in twitcher mice"

Quantifies the depletion achieved by the pharmacological arm of the discordance, which is the arm that produced no survival benefit.

Does cell-autonomous neuronal toxicity contribute materially to disease in human Krabbe patients in vivo, or is it a property of converted-cell and rodent systems that does not scale to the infantile disease where demyelination dominates?

HUMAN MODEL MISMATCH OPEN gap_krabbe_neuronal_arm_human_relevance

Attached to

pathophysiology#Cell-Autonomous Neuronal Toxicity

The evidence for the neuronal arm is real but narrow in a specific way. The human data come from induced neurons converted from the fibroblasts of two adult-onset compound heterozygotes, a culture system with no oligodendrocytes and no in vivo context, while the functional electrophysiology comes from twitcher mouse hippocampus. Human neuropathology of Krabbe disease has been reported mainly in terms of white matter, globoid cells, and gliosis, and no in vivo rescue experiment has isolated the neuronal contribution. Getting this right matters clinically rather than only descriptively: if neurons are injured independently of myelin, that is a candidate explanation for the residual progression seen after hematopoietic stem cell transplantation, and it would argue that restoring GALC to the myelinating and phagocytic compartments alone is not enough.

Proposed experiments

Cell-type-restricted GALC restoration and human neuronal neuropathology

conditional cell-type-restricted rescue with human post-mortem validation

exp_krabbe_neuron_specific_galc_restoration

In twitcher mice, restore GALC conditionally in neurons alone, in oligodendrocytes alone, and in the myeloid compartment alone, then compare survival, demyelination, and synaptic physiology against global restoration. In parallel, apply single-nucleus transcriptomics and synaptic and neuritic histopathology to post-mortem infantile and late-onset human Krabbe brain, using infant controls, to establish whether the neuronal signature seen in culture is present in human tissue.

Decision criterion

Neuron-restricted GALC restoration that improves synaptic physiology or survival, together with a matching neuronal signature in human tissue, would establish the arm as disease-relevant in humans. Absence of a neuronal signature in human brain, or no benefit from neuron-restricted rescue, would confine the finding to the model systems that generated it.

Would support

pathophysiology#Cell-Autonomous Neuronal Toxicity

Supporting outcome

Neuron-restricted GALC restoration measurably improves synaptic function or survival, and human Krabbe brain shows neuritic and synaptic pathology beyond what demyelination accounts for.

Refuting outcome

Neuron-restricted restoration changes nothing while glial or myeloid restoration reproduces the benefit of global restoration, and human tissue shows no neuron-intrinsic pathology.

Show evidence (1 reference)

PMID:41430252 SUPPORT Model Organism

"Collectively, these findings identify presynaptic sphingolipid accumulation and impaired vesicle docking and fusion as shared mechanisms contributing to synaptic failure in several inherited sphingolipidoses, with potential relevance in adult-onset neurodegenerative diseases where lysosomal..."

The authors themselves frame the human relevance of the synaptic mechanism as potential rather than demonstrated, which is precisely the mismatch this discussion records.

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Pathophysiology

11

GALC Deficiency

Loss-of-function mutations in GALC cause deficiency of the lysosomal enzyme galactosylceramidase.

oligodendrocyte CL:0000128 Schwann cell CL:0002573

GALC hgnc:4115 ↓ DECREASED

galactosylceramide metabolic process GO:0006687 galactosylceramide catabolic process GO:0006683 sphingolipid catabolic process GO:0030149

galactosylceramidase activity GO:0004336 ↓ DECREASED

Downstream

Psychosine Accumulation GALC deficiency leads directly to accumulation of the toxic metabolite psychosine.

GalCer-Driven Macrophage Pathology GALC deficiency also drives an independent parallel arm of disease: macrophages unable to degrade galactosylceramide are transformed into globoid cells by GalCer exposure, producing secondary neuroinflammation.

Show evidence (1 reference)

PMID:31527255 SUPPORT Model Organism

"Infantile globoid cell leukodystrophy (GLD, Krabbe disease) is a fatal demyelinating disorder caused by a deficiency in the lysosomal enzyme galactosylceramidase (GALC). GALC deficiency leads to the accumulation of the cytotoxic glycolipid, galactosylsphingosine (psychosine). "

Confirms GALC deficiency as the initiating enzymatic defect in Krabbe disease.

Psychosine Accumulation

Psychosine is the key toxic lipid that accumulates in Krabbe disease.

oligodendrocyte CL:0000128 Schwann cell CL:0002573

brain white matter UBERON:0003544 cerebral hemisphere white matter UBERON:0002437

Downstream

Oligodendrocyte and Schwann Cell Toxicity Psychosine accumulation is toxic to myelin-producing cells in both CNS and PNS.

Globoid Cell Accumulation Psychosine can drive MMP-3-mediated transformation of microglia into multinucleated globoid cells, connecting the storage metabolite to a hallmark macrophage/microglial lesion.

Proteostasis Failure Psychosine accumulation impairs autophagy and ubiquitin-proteasome handling.

Cell-Autonomous Neuronal Toxicity Psychosine injures neurons directly, without requiring loss of the myelin they are ensheathed by.

Show evidence (2 references)

PMID:31527255 SUPPORT Model Organism

"Infantile globoid cell leukodystrophy (GLD, Krabbe disease) is a fatal demyelinating disorder caused by a deficiency in the lysosomal enzyme galactosylceramidase (GALC). GALC deficiency leads to the accumulation of the cytotoxic glycolipid, galactosylsphingosine (psychosine). "

Confirms psychosine accumulation as the key toxic storage abnormality in Krabbe disease.

PMID:31527255 SUPPORT Model Organism

"psychosine is generated catabolically through the deacylation of galactosylceramide by acid ceramidase (ACDase) "

Demonstrates the catabolic pathway of psychosine generation via acid ceramidase, clarifying the mechanism of psychosine synthesis.

Oligodendrocyte and Schwann Cell Toxicity

Psychosine toxicity injures myelin-producing oligodendrocytes and Schwann cells.

oligodendrocyte CL:0000128 Schwann cell CL:0002573

Downstream

Demyelination Toxic injury to myelin-producing cells drives downstream demyelination.

Show evidence (1 reference)

PMID:7354254 SUPPORT Human Clinical

"The concentration of psychosine will steadily increase and reach toxic levels and kill the oligodendroglial cells. This results in an arrest of the galactosylceramide biosynthesis. "

This seminal paper directly supports oligodendroglial toxicity from psychosine accumulation.

Demyelination

Krabbe disease causes progressive loss of myelin in the central and peripheral nervous systems.

oligodendrocyte CL:0000128 microglial cell CL:0000129 macrophage CL:0000235

myelination GO:0042552 ↓ DECREASED central nervous system myelination GO:0022010 ↓ DECREASED

brain white matter UBERON:0003544 white matter of spinal cord UBERON:0002318

Downstream

Leukodystrophy CNS demyelination produces the characteristic leukodystrophy phenotype.

Peripheral Neuropathy Peripheral demyelination causes the peripheral neuropathy phenotype.

Spasticity Central motor-tract and white-matter demyelination contributes to early spasticity in infantile and later-onset Krabbe disease.

Developmental Regression Progressive CNS demyelination and neurodegeneration cause loss of acquired developmental milestones.

Irritability in Infancy Infantile Krabbe disease often first presents with irritability during the rapidly progressive neurodegenerative phase.

Seizures Progressive CNS white-matter disease and neurodegeneration are associated with seizures during infantile Krabbe disease.

Optic Atrophy Visual pathway involvement during CNS demyelination can progress to optic atrophy in a subset of patients.

Feeding Difficulties Progressive neurologic deterioration causes swallowing and feeding impairment, often requiring tube feeding in infantile disease.

Show evidence (1 reference)

PMID:36113749 SUPPORT Human Clinical

"Functional deficiency of GALC is toxic to myelin-producing cells, which leads to progressive demyelination in both the central and peripheral nervous systems. "

Neuropathological study of human Krabbe disease brains confirming progressive demyelination in CNS and PNS due to GALC deficiency.

Cell-Autonomous Neuronal Toxicity

Psychosine injures neurons directly, in parallel with rather than downstream of oligodendrocyte and Schwann cell death. Induced neurons converted from adult-onset Krabbe patient fibroblasts show neurite fragmentation and abnormal neuritic branching alongside the expected loss of GALC activity and rise in psychosine, and psychosine applied to neurons from healthy individuals is sufficient to reproduce those defects. In the twitcher mouse, psychosine concentrates in presynaptic membranes and synaptic vesicles, and hippocampal neurons show cell-autonomous reductions in paired-pulse facilitation and excitatory postsynaptic potential amplitude. This arm means Krabbe disease is not exclusively a disorder of myelinating glia, and it is one candidate explanation for why transplantation does not fully arrest progression.

neuron CL:0000540

neuron projection development GO:0031175 synaptic vesicle cycle GO:0099504

Show evidence (2 references)

PMID:27780934 SUPPORT In Vitro

"directly converted KD iNeurons showed not only diminished GALC activity and increased psychosine levels, as expected, but also neurite fragmentation and abnormal neuritic branching"

Neurons converted directly from the fibroblasts of two adult-onset Krabbe patients carry a neuronal phenotype in a system that contains no oligodendrocytes, so the defect cannot be secondary to demyelination. Scope caveat: both donors were adult-onset compound heterozygotes, so extrapolation to infantile disease is an inference.

PMID:41430252 SUPPORT Model Organism

"In vivo electrophysiological recording revealed significant cell autonomous reductions in paired-pulse facilitation and excitatory postsynaptic potential amplitude in hippocampal neurons of TWI mice."

Extends the neuronal arm from morphology to function in vivo, and locates psychosine in the presynaptic compartment where the deficit is measured.

GalCer-Driven Macrophage Pathology

GALC-deficient macrophages cannot degrade galactosylceramide (GalCer); when exposed to GalCer they are transformed into globoid cells and drive a more severe phenotype, independent of psychosine-induced oligodendrocyte demyelination. This identifies a parallel disease arm driven by macrophage-autonomous GalCer storage and explains why HSCT (delivering healthy phagocytic macrophages) reduces nerve globoid cells without requiring efficient enzyme cross-correction.

macrophage CL:0000235

Show evidence (2 references)

PMID:32375064 SUPPORT In Vitro

"macrophages require GALC to degrade myelin, as Galc-deficient macrophages are transformed into globoid cells by exposure to galactosylceramide and produce a more severe GLD phenotype"

Direct experimental demonstration that GalCer accumulation in GALC-deficient macrophages — independent of psychosine — drives globoid-cell transformation and exacerbates the GLD phenotype, supporting a parallel macrophage-autonomous arm of the canonical model.

PMID:37337846 SUPPORT Model Organism

"Bone marrow-derived macrophages from both Twi and Twi/Sap-D KO mice produced significant amounts of TNF-α upon exposure to GalCer and were transformed into globoid cells"

Independent corroboration of this arm from a different laboratory and a different genetic model. It carries extra weight because it comes from the study that eliminated psychosine: macrophages still became globoid cells and still released TNF-alpha on GalCer exposure, which is what the authors propose as the psychosine-independent route to the residual demyelination.

Globoid Cell Accumulation

Multinucleated globoid macrophages accumulate in Krabbe disease white matter as a hallmark neuropathologic lesion.

microglial cell CL:0000129 macrophage CL:0000235

Show evidence (1 reference)

PMID:36113749 SUPPORT Human Clinical

"an early-infantile case (age of death at 10 months) had about 3-fold increases in both globoid cells, a pathological hallmark for KD "

Quantifies the presence of globoid cells as a hallmark neuropathologic lesion in Krabbe disease.

Microglial and Astrocyte Reactivity

Krabbe disease triggers marked activation of microglia and astrocytes in affected white matter.

microglial cell CL:0000129 astrocyte CL:0000127

Downstream

Inflammasome Activation Activated glial cells participate in downstream inflammasome-related inflammatory signaling.

Show evidence (1 reference)

PMID:37048066 SUPPORT Model Organism

"The astrocytes and microglia reactivity were attenuated in that reactive astrocytes, ameboid microglia, and globoid cells were reduced in the brains of rapamycin-treated twitcher mice "

Demonstrates robust astrocyte and microglial reactivity in twitcher mouse brains, supporting a distinct glial-reactivity node.

Inflammasome Activation

Non-canonical (caspase-11) and canonical (caspase-1) inflammasome pathways and gasdermin D are progressively induced in nervous tissue in Krabbe disease. Caspase-11 localizes to reactive microglia/macrophages and astrocytes, while caspase-1 and gasdermin D are restricted to reactive microglia/macrophages. This inflammasome signature accompanies demyelination and gliosis and may represent a therapeutic target.

microglial cell CL:0000129 astrocyte CL:0000127

inflammatory response GO:0006954

spinal cord UBERON:0002240 brain white matter UBERON:0003544

Show evidence (2 references)

PMID:36519759 SUPPORT Model Organism

"the expression of pro-inflammatory non-canonical caspase-11, canonical caspase-1, gasdermin D and cognate genes is induced in nervous tissue "

Establishes that inflammasome-associated genes including caspase-11, caspase-1, and gasdermin D are progressively induced in twitcher mouse nervous tissue, identifying a new pathogenic mechanism in Krabbe disease.

PMID:36519759 SUPPORT Model Organism

"Caspase-11 is found in reactive microglia/macrophages as well as astrocytes but caspase-1 and gasdermin D are restricted to reactive microglia/macrophages "

Defines cell-type-specific expression patterns of inflammasome components in Krabbe disease nervous tissue.

Proteostasis Failure

Psychosine causes dysfunction of autophagy and the ubiquitin-proteasome system, leading to accumulation of insoluble ubiquitinated protein aggregates in the brain. This proteostasis failure contributes to neurodegeneration and can be partially rescued by mTOR inhibition with rapamycin.

autophagy GO:0006914

brain white matter UBERON:0003544

Downstream

Microglial and Astrocyte Reactivity Psychosine-driven proteostasis failure contributes to neuroinflammatory glial reactivity; reducing aggregate burden attenuates reactive astrocytes and ameboid microglia in the twitcher model.

Show evidence (2 references)

PMID:37048066 SUPPORT Model Organism

"psychosine causes dysfunction of autophagy and the ubiquitin-proteasome system underlying the pathogenesis of globoid cell leukodystrophy (GLD), a devastating lysosomal storage disease complicated by global demyelination "

Establishes that psychosine-driven proteostasis failure through autophagy and UPS dysfunction is a key pathogenic mechanism in globoid cell leukodystrophy.

PMID:37048066 SUPPORT Model Organism

"significantly reduced the accumulation of insoluble ubiquitinated protein and the formation of ubiquitin aggregates "

Demonstrates that mTOR inhibition with rapamycin can reduce protein aggregate burden in twitcher mouse brains, validating proteostasis failure as a tractable therapeutic target.

Adaptive Immune Cell Infiltration

Beyond innate microglial and astrocytic activation, Krabbe disease white matter shows infiltration of CD8-positive T lymphocytes, an adaptive immune component whose burden tracks with clinical severity and neuropathology (greater in a more rapidly fatal early-infantile case than in a slower-progressing infantile case). This extends the Krabbe neuroinflammatory picture beyond the innate arm to include adaptive immunity.

CD8-positive T lymphocyte CL:0000625

adaptive immune response GO:0002250

brain white matter UBERON:0003544

Show evidence (1 reference)

PMID:36113749 SUPPORT Human Clinical

"increases in both globoid cells, a pathological hallmark for KD, and CD8-positive T lymphocytes, a pathological marker for multiple sclerosis, in the white matter "

Human Krabbe disease brain neuropathology identifies CD8-positive T lymphocyte infiltration in white matter, with greater burden in the more severe early-infantile case, evidencing an adaptive immune contribution to the disease that correlates with clinical severity.

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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

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Phenotypes

8

Digestive 1

Feeding Difficulties HP:0011968

Show evidence (1 reference)

PMID:32912261 SUPPORT Human Clinical

"Irritability, abnormalities in movement pattern as well as general developmental regression were the first symptoms in the infantile group; disease course was severe with rapid progression, e.g. loss of visual fixation, need for tube feeding and then an early death. "

This natural history study supports clinically significant feeding dysfunction in infantile Krabbe disease through the frequent need for tube feeding during rapid progression.

Eye 1

Optic Atrophy HP:0000648

Show evidence (1 reference)

PMID:10992329 SUPPORT Human Clinical

"Optic atrophy was uncommon in our series (present only in a single case). "

This enzymatically confirmed pediatric Krabbe disease series documents optic atrophy in one patient.

Musculoskeletal 1

Spasticity HP:0001257

Show evidence (1 reference)

PMID:32912261 SUPPORT Human Clinical

"Developmental and disease trajectories were described based on the acquisition and loss of milestones as well as the time of first clearly identifiable symptoms and needs such as spasticity, seizures and tube feeding. "

This natural history study directly identifies spasticity as a tracked neurological manifestation in Krabbe disease, providing more specific support than generic motor-delay language.

Nervous System 5

Leukodystrophy HP:0002415

Show evidence (1 reference)

PMID:32912261 SUPPORT Human Clinical

"The different forms of the disease were characterized by different MRI patterns (infantile: diffuse white matter involvement and cerebellar structures specifically affected, later onset: parieto-occipital white matter and splenium affected, adult: motor tracts specifically affected). "

This natural history study directly documents characteristic white-matter MRI abnormalities across Krabbe disease forms, supporting leukodystrophy as an observed phenotype.

Peripheral Neuropathy Demyelinating peripheral neuropathy HP:0007108

Show evidence (1 reference)

PMID:36113749 SUPPORT Human Clinical

"Functional deficiency of GALC is toxic to myelin-producing cells, which leads to progressive demyelination in both the central and peripheral nervous systems. "

Confirms peripheral nervous system demyelination as a feature of Krabbe disease due to toxicity to Schwann cells, the myelin-producing cells of the PNS.

Irritability in Infancy HP:0000737

Show evidence (1 reference)

PMID:32912261 SUPPORT Human Clinical

"Irritability, abnormalities in movement pattern as well as general developmental regression were the first symptoms in the infantile group "

This natural history study directly identifies irritability as one of the first symptoms in infantile Krabbe disease.

Seizures HP:0001250

Show evidence (1 reference)

PMID:10992329 SUPPORT Human Clinical

"Most of the children with infantile disease presented with neurodegeneration, seizures or fever "

Clinical series of nine children with enzymatically confirmed Krabbe disease documents seizures as a presenting feature in infantile KD.

Developmental Regression HP:0002376

Show evidence (1 reference)

PMID:32912261 SUPPORT Human Clinical

"Irritability, abnormalities in movement pattern as well as general developmental regression were the first symptoms in the infantile group "

Nationwide German natural history study of 38 Krabbe patients documents developmental regression as a frequent first symptom in infantile KD.

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Genetic Associations

1

GALC (Pathogenic Mutations)

Gene: GALC hgnc:4115

Autosomal Recessive

Show evidence (4 references)

PMID:8634707 SUPPORT Human Clinical

"the deletion is approximately 30 kb starting near the middle of the 12 kb intron 10, and includes all of the coding region through exon 17 plus an additional 9 kb "

Characterizes the large ~30 kb deletion in the GALC gene, one of the most common mutations causing infantile Krabbe disease.

PMID:7581365 SUPPORT Human Clinical

"a large deletion, together with a polymorphic C to T transition at position 502 of cDNA (counting from the A of the initiation codon), is responsible for a large number of disease-causing alleles in patients with Krabbe disease "

Demonstrates that the large deletion plus 502C>T polymorphism is a common mutant allele in infantile Krabbe disease, found in homozygous or heterozygous state in the majority of patients tested.

PMID:36113749 SUPPORT Human Clinical

"Krabbe Disease (KD) is an autosomal recessive disorder that results from loss-of-function mutations in the GALC gene, which encodes lysosomal enzyme galactosylceramidase (GALC). "

Confirms autosomal recessive inheritance and GALC loss-of-function as the genetic basis of Krabbe disease.

+ 1 more reference

Variants (1)

30-kb deletion (intron 10-17)

Large deletion encompassing exons 11-17, the most common pathogenic variant in European populations.

💊

Medical Actions

5

Hematopoietic Stem Cell Transplantation

Action: hematopoietic stem cell transplantation Ontology label: Hematopoietic Cell Transplantation NCIT:C15431

Platform: Cell therapy

HSCT is the only treatment shown to alter disease course when performed presymptomatically in infantile Krabbe disease or early in later-onset forms. It provides donor-derived enzyme to the CNS via engrafted microglia. For infantile KD, transplantation must occur within the first 30-45 days of life to be effective.

Mechanism Target:

RESTORES GALC Deficiency — Donor-derived hematopoietic cells restore galactocerebrosidase activity in blood after successful engraftment.

Show evidence (1 reference)

PMID:15901860 SUPPORT Human Clinical

"Surviving patients showed durable engraftment of donor-derived hematopoietic cells with restoration of normal blood galactocerebrosidase levels. "

The cord-blood transplantation study directly supports restoration of the deficient enzyme activity after donor-cell engraftment.

MODULATES Demyelination — Presymptomatic transplantation can permit progressive central myelination and alter the infantile disease trajectory.

Show evidence (1 reference)

PMID:15901860 SUPPORT Human Clinical

"Infants who underwent transplantation before the development of symptoms showed progressive central myelination and continued gains in developmental skills "

Presymptomatic cord-blood transplantation is associated with continued myelination, supporting a disease-modifying effect on the demyelination pathway.

Show evidence (2 references)

PMID:15901860 SUPPORT Human Clinical

"Infants who underwent transplantation before the development of symptoms showed progressive central myelination and continued gains in developmental skills, and most had age-appropriate cognitive function and receptive language skills "

Landmark NEJM study demonstrating that presymptomatic cord blood transplantation favorably alters disease course in infantile Krabbe disease with continued myelination and developmental gains.

PMID:15901860 SUPPORT Human Clinical

"Children who underwent transplantation after the onset of symptoms had minimal neurologic improvement. "

Demonstrates that HSCT after symptom onset has minimal benefit, underscoring the critical importance of early/presymptomatic treatment.

Gene Therapy (Investigational)

Action: gene therapy Ontology label: Gene Therapy NCIT:C15238

Platform: Gene therapy

AAV-mediated gene therapy to restore GALC expression is under active investigation. Preclinical studies in mouse and canine models show that CNS-directed AAV-GALC can normalize psychosine and extend survival. Combination of systemic AAV gene therapy with HSCT has shown the most promising results in canine models, with clinical trials underway (NCT04693598, NCT05739643).

Mechanism Target:

RESTORES GALC Deficiency — AAV-GALC therapy is designed to restore GALC expression in the CNS.

Show evidence (1 reference)

PMID:37628569 SUPPORT Model Organism

"To rescue GALC gene function in the CNS of the twitcher mouse model of KD, an adeno-associated virus serotype 1 vector expressing murine GALC under control of a chicken β-actin promoter (AAV1-GALC) was administered to newborn mice "

The preclinical study explicitly frames AAV1-GALC as restoring GALC gene function in the CNS.

INHIBITS Psychosine Accumulation — CNS-directed AAV-GALC lowers or normalizes psychosine accumulation in treated twitcher mice.

Show evidence (1 reference)

PMID:37628569 SUPPORT Model Organism

"Functionally, elevated levels of psychosine were completely normalized in the forebrain region of the treated mice. "

Treated twitcher mice show normalization of elevated psychosine in forebrain, supporting psychosine lowering as a target effect.

Show evidence (2 references)

PMID:37628569 SUPPORT Model Organism

"elevated levels of psychosine were completely normalized in the forebrain region of the treated mice "

AAV1-GALC gene therapy delivered via intracerebroventricular injection normalized psychosine in the forebrain and extended median lifespan from 43 to 78 days in the twitcher mouse model.

PMID:37628569 SUPPORT Model Organism

"The median lifespan was extended from 43 days to 78 days (range: 74-88 days) in the AAV1-GALC-treated group "

Demonstrates significant survival extension with CNS-directed AAV1-GALC gene therapy in the twitcher mouse model.

Supportive Care

Action: Supportive Care NCIT:C15747

Symptomatic management including physical therapy, antispasmodics, nutritional support, and seizure management.

Target Phenotypes: Spasticity HP:0001257 Feeding difficulties HP:0011968 Seizure HP:0001250

Show evidence (1 reference)

PMID:20301416 SUPPORT Other

"Treatment of a child who is symptomatic before age six months is supportive and focused on increasing the quality of life and avoiding complications. "

GeneReviews supports supportive care for symptomatic early infantile Krabbe disease, which is represented as addressing the major symptomatic neurologic complications.

Avoidance of disease-accelerating agents

Action: supportive care Ontology label: Supportive Care NCIT:C15747

GeneReviews lists atypical antipsychotics, multi-drug seizure regimens that cause over-sedation, and routine childhood vaccinations as agents/circumstances to avoid because they can affect cognition, respiratory drive, neurologic decline, or disease progression.

Target Phenotypes: Seizure HP:0001250

Show evidence (1 reference)

PMID:20301416 SUPPORT Other

"Agents/circumstances to avoid: Atypical antipsychotics and multiple medications for seizures can cause over-sedation (affecting cognition, respiratory drive, and rate of neurologic decline). Routine childhood vaccinations can accelerate disease progression. "

GeneReviews explicitly identifies medication over-sedation risks and routine childhood vaccinations as agents or circumstances to avoid in Krabbe disease management.

Substrate Reduction Therapy (Investigational)

Action: Pharmacotherapy NCIT:C15986

Agent: carmofur CHEBI:31360

Platform: Small molecule

Because psychosine is generated catabolically by acid ceramidase (ACDase) deacylating galactosylceramide, ACDase inhibition is an emerging substrate reduction strategy that uncouples GALC deficiency from psychosine synthesis. Genetic ablation of ACDase in the twitcher mouse eliminates psychosine accumulation and rescues the phenotype, and pharmacological ACDase inhibition with carmofur lowers psychosine and extends twitcher lifespan. This approach is preclinical/investigational.

Mechanism Target:

INHIBITS Psychosine Accumulation — Acid ceramidase inhibition uncouples GALC deficiency from psychosine biogenesis, lowering the toxic storage metabolite.

Show evidence (1 reference)

PMID:31527255 SUPPORT Model Organism

"pharmacological inhibition of ACDase activity with carmofur significantly decreases psychosine accumulation in cells from a Krabbe patient and prolongs the life span of the twitcher (Twi) mouse "

Carmofur, an acid ceramidase inhibitor, decreases psychosine and extends survival in the twitcher model, supporting substrate reduction therapy targeting psychosine biogenesis.

Show evidence (1 reference)

PMID:31527255 SUPPORT Model Organism

"genetic loss of ACDase activity (Farber disease) in the GALC-deficient mouse model of human GLD (twitcher) eliminates psychosine accumulation and cures GLD "

Genetic ablation of acid ceramidase in twitcher mice eliminates psychosine accumulation and rescues the phenotype, providing proof of concept for substrate reduction therapy in Krabbe disease.

🔬

Biochemical Markers

2

Psychosine (Galactosylsphingosine) (Elevated)

Context: Key toxic metabolite and biomarker. Blood psychosine levels used for newborn screening second-tier testing. Infantile KD typically shows levels >=10 nM; late-infantile KD shows 2-10 nM.

Pathograph Readouts

Readout Of Psychosine Accumulation Positive Diagnostic

Elevated psychosine reports the proximal toxic sphingolipid storage abnormality caused by GALC deficiency.

Show evidence (1 reference)

PMID:20301416 SUPPORT Other

"elevated psychosine levels can also help establish the diagnosis. "

GeneReviews identifies elevated psychosine as a diagnostic marker for Krabbe disease.

Show evidence (2 references)

PMID:31527255 SUPPORT Model Organism

"GALC deficiency leads to the accumulation of the cytotoxic glycolipid, galactosylsphingosine (psychosine) "

Confirms psychosine accumulation as the primary biochemical abnormality in Krabbe disease due to GALC deficiency.

PMID:38390974 SUPPORT Human Clinical

"a two-tiered strategy based on psychosine (PSY) as the determinant if an NBS result is positive or negative after a first-tier test revealed decreased galactocerebrosidase activity "

Psychosine is used as a second-tier newborn screening biomarker, confirming its diagnostic utility as an elevated metabolite in Krabbe disease.

GALC Enzyme Activity (Reduced)

Context: Galactosylceramidase enzyme activity is deficient in all forms of Krabbe disease. Measured in leukocytes or dried blood spots as the first-tier newborn screening test.

Pathograph Readouts

Readout Of GALC Deficiency Negative Diagnostic

Low leukocyte or dried-blood-spot GALC enzyme activity directly reports the initiating galactosylceramidase deficiency.

Show evidence (1 reference)

PMID:20301416 SUPPORT Other

"established by detection of deficient GALC enzyme activity in leukocytes. "

GeneReviews identifies deficient leukocyte GALC enzyme activity as the diagnostic biochemical readout.

Show evidence (1 reference)

PMID:36113749 SUPPORT Human Clinical

"homozygous null mutations in GALC lead to deficiency in total GALC protein and activity "

Confirms that null GALC mutations lead to complete deficiency in GALC protein and enzyme activity in infantile Krabbe disease brains.

🔬

Diagnosis

2

Newborn Screening

Two-tiered newborn screening strategy using GALC enzyme activity as first-tier test on dried blood spots, followed by psychosine measurement as second-tier determinant. Krabbe disease is part of newborn screening in 11 US states.

newborn screening NCIT:C81178

galactocerebrosidase (GALC) activity, DBS LOINC:62310-8 psychosine, DBS (second tier) LOINC:93688-0

Reference Ranges

Psychosine [Moles/volume] in DBS (newborn screening, Illinois (USA) programme, 8 December 2017 to 31 December 2020; second-tier psychosine on specimens with low GALC activity, cut-off of the reference laboratory that ran the assay)

Negative psychosine (< 2.0 nmol/L) Intermediate psychosine (2.0–8.7 nmol/L) Abnormal psychosine, immediate referral (≥ 8.7 nmol/L)

Negative psychosine: In this programme the low-GALC specimens with psychosine in this tier carried pseudodeficiency alleles, a single pathogenic variant or a variant of uncertain significance, and no follow-up was recommended.

Intermediate psychosine: Mildly elevated; infants in this tier whose GALC sequencing showed two pathogenic variants were followed as suspected late-onset Krabbe disease rather than referred for transplant evaluation.

Abnormal psychosine, immediate referral: Triggered immediate referral for evaluation for hematopoietic stem cell transplantation as presumptive infantile Krabbe disease; the two infantile cases the programme found had psychosine of 10 and 35 nM.

The source writes the unit as nM; nmol/L is the UCUM spelling of the same unit, not a conversion. The programme states the abnormal rule as psychosine "greater than or equal to 8.7 nM", so the inclusive lower bound of the top band matches the source exactly. The intermediate tier is written ">2-<8.7 nM" and the negative tier "<2.0 nM", so the source assigns exactly 2.0 to neither; the half-open convention puts it in the intermediate band. The intermediate tier is not a referral rule on its own: the programme followed those infants only when GALC sequencing found pathogenic variants. The same paper says the laboratory was updating its psychosine cut-off to 10 nM to agree with other testing laboratories, so 8.7 is recorded as the cited period's value and not as a property of the analyte.

Show evidence (4 references)

PMID:34065072 SUPPORT Human Clinical

"Abnormal PSY level (greater than or equal to 8.7 nM; PerkinElmer Genetics, Inc., Pittsburg, PA, USA) and/or detection of a homozygous 30-kb deletion triggered immediate referral to a consultant/specialized center for the purpose of evaluation for HSCT"

States the dried-blood-spot psychosine threshold at which the Illinois programme referred a newborn immediately for infantile Krabbe disease evaluation.

PMID:34065072 SUPPORT Human Clinical

"an intermediate group of infants who had mildly elevated PSY (>2–<8.7 nM) in the newborn screen specimen and had two pathogenic mutations were followed up regularly due to high risk for late-onset disease"

Defines the intermediate psychosine tier and the genotype condition attached to following it up for later-onset disease.

PMID:34065072 SUPPORT Human Clinical

"For the negative category, all specimens had negative/normal PSY levels (<2.0 nM), and the GALC gene sequencing revealed the presence of pseudodeficiency alleles."

States the psychosine level the programme treated as negative, which is the open-below band.

+ 1 more reference

Measurements bind the method-less quantitative DBS codes; the specimen is intrinsic to a newborn screen, so the DBS code is the test's identity here rather than a method-specific variant. The first-tier GALC activity carries no band because the cited programmes state the rule as a fraction of the run's own median or mean rather than in the code's unit: Illinois repeated any specimen at or below 16% of the batch median and called a screen positive at or below 13% of the batch median; New York State sent specimens at or below 12% of the daily mean to molecular analysis. A percentage of a batch statistic cannot be carried as a band on an activity-per-volume code, so those rules are recorded as evidence here instead. The Illinois paper states its repeat trigger inclusively in its methods and call-out table ("less than or equal to 16%", "≤16") and once as "<16%" in its discussion; the quoted methods wording is the one recorded. The psychosine cut-off is programme- and laboratory-specific and is recorded as the cited period's value; the same paper's table footnote gives the complementary statement "PSY normal range < 8.7 nM", which agrees with the quoted rule.

Show evidence (5 references)

PMID:34065072 SUPPORT Human Clinical

"An initial screen for GALC was performed in a single punch, and if the GALC activity was less than or equal to 16% of the batch median, the analysis was repeated in five replications. A positive GALC screen was defined as a mean of repeated activity of less than or equal to 13% of the batch median."

States the Illinois first-tier GALC activity rule as a percentage of the batch median, which is why the GALC measurement carries no numeric band.

PMID:26795590 SUPPORT Human Clinical

"Dried blood spots from newborns were assayed for GALC enzyme activity using mass spectrometry, followed by molecular analysis for those with low activity (≤12% of the daily mean)."

States the New York State first-tier GALC rule, again as a percentage of the run's mean, and documents the dried-blood-spot GALC activity measurement bound here.

PMID:34065072 SUPPORT Human Clinical

"Our data show that a high percentage of reduced GALC activity (62%) was due to the presence of pseudodeficiency alleles in the GALC gene."

Shows that a low first-tier GALC activity is mostly produced by pseudodeficiency rather than disease, which is why the second-tier psychosine measurement is bound beside it.

+ 2 more references

GALC Enzyme Activity Assay

Measurement of galactosylceramidase activity in leukocytes or fibroblasts. Deficient activity confirms the diagnosis, though pseudodeficiency alleles can complicate interpretation.

Show evidence (1 reference)

PMID:36113749 SUPPORT Human Clinical

"homozygous null mutations in GALC lead to deficiency in total GALC protein and activity "

Demonstrates that GALC protein and enzyme activity measurement can distinguish infantile Krabbe disease cases with null mutations.

📈

Progression

3

Infantile Onset

Age: 0-6 months

Most common form. Rapid neurological deterioration with irritability, spasticity, feeding difficulties, and developmental regression. Death typically occurs before age 2 years.

Late-Infantile/Juvenile Onset

Age: 6 months - 16 years

Progressive gait disturbance, visual impairment, and cognitive decline with slower progression than the infantile form.

Adult Onset

Age: >16 years

Rarest form with slowly progressive spastic paraparesis, peripheral neuropathy, and variable cognitive involvement.

📊

Prevalence

1

Global

Rare Rare

Estimated incidence of 1 in 100,000 to 250,000 live births. Infantile onset accounts for approximately 85-90% of cases.

📊

Related Datasets

1

Metabolic profiling reveals biochemical pathways and potential biomarkers associated with the pathogenesis of Krabbe disease metabolomics_workbench:ST000352

Located via OmicsDI, which aggregates across omics repositories; this record comes from metabolomics_workbench. Only repositories with no other discovery route in this project and with a working accession resolver are curated from OmicsDI -- GEO, ArrayExpress, PRIDE, MetaboLights and EGA hits are excluded as duplicates of dedicated passes. Matched because the disease is named in the dataset's own title ("Krabbe Disease"). Retrieved 2026-08-02.

{ }

Source YAML

click to show

name: Krabbe Disease
creation_date: "2026-03-14T00:00:00Z"
description: >
  Krabbe disease (globoid cell leukodystrophy) is a severe autosomal recessive
  lysosomal storage disorder caused by deficiency of galactosylceramidase (GALC),
  the enzyme responsible for degrading galactosylceramide and psychosine
  (galactosylsphingosine). Accumulation of psychosine is toxic to
  oligodendrocytes and Schwann cells, leading to progressive demyelination
  of the central and peripheral nervous systems. The infantile form presents
  in the first months of life with irritability, spasticity, and rapid
  neurological deterioration, while later-onset forms have a more variable
  and protracted course.
category: Genetic
disease_term:
  preferred_term: Krabbe disease
  term:
    id: MONDO:0009499
    label: Krabbe disease
parents:
- Leukodystrophy
- Lysosomal Storage Disease
- Sphingolipidosis
references:
- reference: PMID:20301416
  title: Krabbe Disease.
  tags:
  - GeneReviews
  findings: []
prevalence:
- population: Global
  prevalence_class: RARE
  percentage: Rare
  notes: >
    Estimated incidence of 1 in 100,000 to 250,000 live births.
    Infantile onset accounts for approximately 85-90% of cases.
progression:
- phase: Infantile Onset
  age_range: 0-6 months
  notes: >
    Most common form. Rapid neurological deterioration with irritability,
    spasticity, feeding difficulties, and developmental regression.
    Death typically occurs before age 2 years.
- phase: Late-Infantile/Juvenile Onset
  age_range: 6 months - 16 years
  notes: >
    Progressive gait disturbance, visual impairment, and cognitive decline
    with slower progression than the infantile form.
- phase: Adult Onset
  age_range: ">16 years"
  notes: >
    Rarest form with slowly progressive spastic paraparesis, peripheral
    neuropathy, and variable cognitive involvement.
mechanistic_hypotheses:
- hypothesis_group_id: canonical_galc_deficiency_psychosine_demyelination_model
  hypothesis_label: Canonical GALC Deficiency / Psychosine-Mediated Demyelination Model
  status: CANONICAL
  description: >-
    Krabbe disease (globoid cell leukodystrophy) is an autosomal recessive lysosomal storage disorder
    caused by loss-of-function variants in GALC encoding galactocerebrosidase. Loss of GALC activity
    prevents lysosomal hydrolysis of galactosylceramide but, critically, also fails to clear its toxic
    deacylated lyso-derivative galactosylsphingosine (psychosine). Psychosine accumulation in
    oligodendrocytes and Schwann cells triggers apoptosis of myelin-forming cells, secondary lipid-laden
    multinucleated macrophages (globoid cells), and progressive CNS and peripheral demyelination. The
    infantile form (~85% of cases) presents in the first 6 months with irritability, hypertonia,
    opisthotonus, seizures, blindness, and death by age 2-3 in untreated patients. Pre-symptomatic
    hematopoietic stem cell transplantation (the only available disease-modifying therapy), the twitcher
    mouse model (Galc^trs/trs) faithfully recapitulating the human phenotype, and AAV-GALC gene therapy
    corroborate the GALC-deficiency / psychosine-toxicity / demyelination axis as the canonical
    pathogenic mechanism.
  notes: >-
    Retained as CANONICAL with required expansion to
    multi-mechanism framework. The 2026 openscientist
    hypothesis-search report
    (kb/hypotheses/Krabbe_Disease/canonical_galc_deficiency_psychosine_demyelination_model)
    finds SUPPORTED with significant qualifications. The core
    GALC-deficiency → psychosine-accumulation → demyelination
    cascade is quantitatively validated: residual GALC activity
    across 31 missense variants correlates with age of onset
    (Pearson r > 0.94); acid ceramidase ablation in twitcher
    mice eliminates psychosine and reportedly CURES GLD; gene
    therapy (AAV-GALC) corrects metabolism and extends survival
    in mouse and canine models; psychosine is validated as a
    newborn-screening biomarker. Critical refinement: PSYCHOSINE
    IS NECESSARY BUT NOT SUFFICIENT — (1) saposin-D ablation in
    twitcher mice eliminates psychosine accumulation yet fails
    to prevent late-stage demyelination (and even shortens
    lifespan); (2) a UGT8 inhibitor reduces psychosine by
    72–86% without extending lifespan. The canonical model must
    expand to incorporate parallel/downstream mechanisms:
    (a) galactosylceramide-driven globoid-cell macrophage
    pathology; (b) neuroinflammation including adaptive
    immunity; (c) cell-autonomous neuronal dysfunction (not just
    oligodendrocyte/Schwann-cell death); (d) autophagy
    dysregulation; (e) UPR / ER stress; (f) emerging α-synuclein
    aggregation and sphingolipid fibril formation. GALC has
    critical functions beyond psychosine degradation.
    Pre-symptomatic HSCT remains the only disease-modifying
    therapy and validates the upstream GALC axis even though it
    does not fully prevent downstream cell-autonomous and
    inflammatory cascades.
  evidence:
  - reference: PMID:31527255
    reference_title: "Genetic ablation of acid ceramidase in Krabbe disease confirms the psychosine hypothesis and identifies a new therapeutic target."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Infantile globoid cell leukodystrophy (GLD, Krabbe disease) is a fatal"
    explanation: >
      Existing canonical mechanism citation in the dismech
      knowledge base, used as the seed for the hypothesis-search
      deep-research run.
  - reference: PMID:40449593
    reference_title: "Quantification profiles of enzyme activity, secretion, and psychosine levels of Krabbe disease galactosylceramidase missense variants."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "residual GALC activity strongly correlated with the age of disease-onset in reported cases (Pearson's r > 0.94, p < 0.0001), suggesting that enzyme activity resulting from MMV expression in this model may serve as a readout for clinical prognostication"
    explanation: >-
      Supplies the quantitative dose-response that this entry's notes previously
      asserted without a citation. A panel of 31 GALC missense variants
      expressed in a GALC-knockout human oligodendrocytic line ties residual
      enzyme activity to reported age of onset. The correlation is against onset
      ages taken from published case reports rather than a prospective cohort.
  - reference: PMID:40449593
    reference_title: "Quantification profiles of enzyme activity, secretion, and psychosine levels of Krabbe disease galactosylceramidase missense variants."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "we observed an inverse correlation between residual GALC activity and endogenous psychosine levels in the MMV panel"
    explanation: >-
      Completes the dose-response chain the hypothesis asserts, linking the
      degree of residual enzyme activity to the amount of psychosine that
      accumulates in the same human cellular model.
  - reference: PMID:37337846
    reference_title: "Genetic ablation of Saposin-D in Krabbe disease eliminates psychosine accumulation but does not significantly improve demyelination."
    supports: REFUTE
    evidence_source: MODEL_ORGANISM
    snippet: "at the later disease stage, qualitatively and quantitatively comparable demyelination occurred in Twi/Sap-D KO mice, particularly in the PNS, and the lifespans of Twi/Sap-D KO mice were even shorter than that of Twi mice"
    explanation: >-
      Refutes the sufficiency half of this hypothesis as written. Saposin-D
      ablation leaves very little psychosine in the CNS or PNS of twitcher mice
      and does delay early demyelination, yet late-stage demyelination is
      comparable and survival is worse. Psychosine accumulation therefore cannot
      by itself account for progressive demyelination; the upstream GALC arm is
      untouched by this result.
  - reference: PMID:35290889
    reference_title: "A novel brain-penetrant oral UGT8 inhibitor decreases in vivo galactosphingolipid biosynthesis in murine Krabbe disease."
    supports: REFUTE
    evidence_source: MODEL_ORGANISM
    snippet: "given the unchanged lifespan, it appears that GALC has critical functions in the nervous system beyond the hydrolysis of galactosylceramide and galactosylsphingosine"
    explanation: >-
      Independent pharmacological corroboration that lowering psychosine is not
      sufficient. The UGT8 inhibitor RA 5557 cut pathologically elevated
      psychosine by 72-86% in midbrain and cerebral cortex without changing
      survival, which the authors read as evidence for GALC functions beyond
      substrate hydrolysis.
pathophysiology:
- name: GALC Deficiency
  conforms_to: "lysosomal_substrate_accumulation#Lysosomal Hydrolase or Cofactor Deficiency"
  description: >
    Loss-of-function mutations in GALC cause deficiency of the lysosomal
    enzyme galactosylceramidase.
  genes:
  - preferred_term: GALC
    term:
      id: hgnc:4115
      label: GALC
    modifier: DECREASED
  molecular_functions:
  - preferred_term: galactosylceramidase activity
    term:
      id: GO:0004336
      label: galactosylceramidase activity
    modifier: DECREASED
  cell_types:
  - preferred_term: oligodendrocyte
    term:
      id: CL:0000128
      label: oligodendrocyte
  - preferred_term: Schwann cell
    term:
      id: CL:0002573
      label: Schwann cell
  biological_processes:
  - preferred_term: galactosylceramide metabolic process
    term:
      id: GO:0006687
      label: glycosphingolipid metabolic process
  - preferred_term: galactosylceramide catabolic process
    term:
      id: GO:0006683
      label: galactosylceramide catabolic process
  - preferred_term: sphingolipid catabolic process
    term:
      id: GO:0030149
      label: sphingolipid catabolic process
  downstream:
  - target: Psychosine Accumulation
    description: GALC deficiency leads directly to accumulation of the toxic metabolite psychosine.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:31527255
      reference_title: "Genetic ablation of acid ceramidase in Krabbe disease confirms the psychosine hypothesis and identifies a new therapeutic target."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >
        Infantile globoid cell leukodystrophy (GLD, Krabbe disease) is a fatal
        demyelinating disorder caused by a deficiency in the lysosomal enzyme
        galactosylceramidase (GALC). GALC deficiency leads to the accumulation
        of the cytotoxic glycolipid, galactosylsphingosine (psychosine).
      explanation: >
        This directly links GALC deficiency to psychosine accumulation.
  - target: GalCer-Driven Macrophage Pathology
    description: >-
      GALC deficiency also drives an independent parallel arm of disease:
      macrophages unable to degrade galactosylceramide are transformed into
      globoid cells by GalCer exposure, producing secondary neuroinflammation.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:32375064
      reference_title: "Macrophages Expressing GALC Improve Peripheral Krabbe Disease by a Mechanism Independent of Cross-Correction."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "macrophages require GALC to degrade myelin, as Galc-deficient macrophages are transformed into globoid cells by exposure to galactosylceramide and produce a more severe GLD phenotype"
      explanation: >-
        Weinstock 2020 establishes a psychosine-independent disease arm:
        GALC deficiency in macrophages prevents GalCer degradation, producing
        secondary neuroinflammation that exacerbates the GLD phenotype.
  evidence:
  - reference: PMID:31527255
    reference_title: "Genetic ablation of acid ceramidase in Krabbe disease confirms the psychosine hypothesis and identifies a new therapeutic target."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >
      Infantile globoid cell leukodystrophy (GLD, Krabbe disease) is a fatal
      demyelinating disorder caused by a deficiency in the lysosomal enzyme
      galactosylceramidase (GALC). GALC deficiency leads to the accumulation
      of the cytotoxic glycolipid, galactosylsphingosine (psychosine).
    explanation: >
      Confirms GALC deficiency as the initiating enzymatic defect in
      Krabbe disease.
- name: Psychosine Accumulation
  conforms_to: "lysosomal_substrate_accumulation#Lysosomal Substrate Accumulation"
  description: >
    Psychosine is the key toxic lipid that accumulates in Krabbe disease.
  cell_types:
  - preferred_term: oligodendrocyte
    term:
      id: CL:0000128
      label: oligodendrocyte
  - preferred_term: Schwann cell
    term:
      id: CL:0002573
      label: Schwann cell
  locations:
  - preferred_term: brain white matter
    term:
      id: UBERON:0003544
      label: brain white matter
  - preferred_term: cerebral hemisphere white matter
    term:
      id: UBERON:0002437
      label: cerebral hemisphere white matter
  downstream:
  - target: Oligodendrocyte and Schwann Cell Toxicity
    description: Psychosine accumulation is toxic to myelin-producing cells in both CNS and PNS.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:7354254
      reference_title: "Krabbe disease: a galactosylsphingosine (psychosine) lipidosis."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >
        The concentration of psychosine will steadily increase and reach toxic
        levels and kill the oligodendroglial cells. This results in an arrest of
        the galactosylceramide biosynthesis.
      explanation: >
        This seminal paper directly links psychosine accumulation to
        oligodendroglial toxicity.
  - target: Globoid Cell Accumulation
    description: >
      Psychosine can drive MMP-3-mediated transformation of microglia into
      multinucleated globoid cells, connecting the storage metabolite to a
      hallmark macrophage/microglial lesion.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:23404611
      reference_title: "MMP-3 mediates psychosine-induced globoid cell formation: implications for leukodystrophy pathology."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >
        Here we report that exposure of primary glial cultures to psychosine
        induces the expression and the production of matrix metalloproteinase
        (MMP)-3 that mediated a morphological transformation of microglia
        into a multinucleated globoid cell type. Additionally,
        psychosine-induced globoid cell formation from microglia was
        prevented by either genetic ablation or chemical inhibition of MMP-3.
      explanation: >
        Primary glial culture experiments identify MMP-3 as an intermediate
        between psychosine exposure and microglial transformation into
        globoid-cell-like multinucleated cells.
  - target: Proteostasis Failure
    description: Psychosine accumulation impairs autophagy and ubiquitin-proteasome handling.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:37048066
      reference_title: "Rapamycin Alleviates Protein Aggregates, Reduces Neuroinflammation, and Rescues Demyelination in Globoid Cell Leukodystrophy."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >
        psychosine causes dysfunction of autophagy and the ubiquitin-proteasome
        system underlying the pathogenesis of globoid cell leukodystrophy (GLD),
        a devastating lysosomal storage disease complicated by global demyelination
      explanation: >
        This directly links psychosine accumulation to proteostasis failure.
  - target: Cell-Autonomous Neuronal Toxicity
    description: >-
      Psychosine injures neurons directly, without requiring loss of the myelin
      they are ensheathed by.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:27780934
      reference_title: "Patient fibroblasts-derived induced neurons demonstrate autonomous neuronal defects in adult-onset Krabbe disease."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "we demonstrated that psychosine was sufficient to induce neurite defects, mitochondrial fragmentation, and lysosomal alterations in iNeurons derived in healthy individuals, thus establishing the causal effect of the cytotoxic GALC substrate in KD and the autonomous neuronal toxicity in KD pathology"
      explanation: >-
        Applying psychosine to neurons converted from healthy individuals
        reproduces the patient neuronal phenotype, which isolates psychosine as
        the sufficient cause of the neuronal defect rather than a consequence of
        demyelination.
  evidence:
  - reference: PMID:31527255
    reference_title: "Genetic ablation of acid ceramidase in Krabbe disease confirms the psychosine hypothesis and identifies a new therapeutic target."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >
      Infantile globoid cell leukodystrophy (GLD, Krabbe disease) is a fatal
      demyelinating disorder caused by a deficiency in the lysosomal enzyme
      galactosylceramidase (GALC). GALC deficiency leads to the accumulation
      of the cytotoxic glycolipid, galactosylsphingosine (psychosine).
    explanation: >
      Confirms psychosine accumulation as the key toxic storage abnormality
      in Krabbe disease.
  - reference: PMID:31527255
    reference_title: "Genetic ablation of acid ceramidase in Krabbe disease confirms the psychosine hypothesis and identifies a new therapeutic target."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >
      psychosine is generated catabolically through the deacylation of
      galactosylceramide by acid ceramidase (ACDase)
    explanation: >
      Demonstrates the catabolic pathway of psychosine generation via
      acid ceramidase, clarifying the mechanism of psychosine synthesis.
- name: Oligodendrocyte and Schwann Cell Toxicity
  conforms_to: "cns_myelin_failure#Oligodendrocyte Differentiation Arrest and Death"
  description: >
    Psychosine toxicity injures myelin-producing oligodendrocytes and Schwann
    cells.
  cell_types:
  - preferred_term: oligodendrocyte
    term:
      id: CL:0000128
      label: oligodendrocyte
  - preferred_term: Schwann cell
    term:
      id: CL:0002573
      label: Schwann cell
  downstream:
  - target: Demyelination
    description: Toxic injury to myelin-producing cells drives downstream demyelination.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:36113749
      reference_title: "Galactosylceramidase deficiency and pathological abnormalities in cerebral white matter of Krabbe disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >
        Functional deficiency of GALC is toxic to myelin-producing cells, which
        leads to progressive demyelination in both the central and peripheral
        nervous systems.
      explanation: >
        This neuropathology study directly links toxicity to myelin-producing
        cells with downstream demyelination.
  evidence:
  - reference: PMID:7354254
    reference_title: "Krabbe disease: a galactosylsphingosine (psychosine) lipidosis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      The concentration of psychosine will steadily increase and reach toxic
      levels and kill the oligodendroglial cells. This results in an arrest of
      the galactosylceramide biosynthesis.
    explanation: >
      This seminal paper directly supports oligodendroglial toxicity from
      psychosine accumulation.
- name: Demyelination
  conforms_to: "cns_myelin_failure#Deficient or Unstable CNS Myelin Sheath"
  description: >
    Krabbe disease causes progressive loss of myelin in the central and
    peripheral nervous systems.
  cell_types:
  - preferred_term: oligodendrocyte
    term:
      id: CL:0000128
      label: oligodendrocyte
  - preferred_term: microglial cell
    term:
      id: CL:0000129
      label: microglial cell
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  biological_processes:
  - preferred_term: myelination
    term:
      id: GO:0042552
      label: myelination
    modifier: DECREASED
  - preferred_term: central nervous system myelination
    term:
      id: GO:0022010
      label: central nervous system myelination
    modifier: DECREASED
  locations:
  - preferred_term: brain white matter
    term:
      id: UBERON:0003544
      label: brain white matter
  - preferred_term: white matter of spinal cord
    term:
      id: UBERON:0002318
      label: white matter of spinal cord
  downstream:
  - target: Leukodystrophy
    description: CNS demyelination produces the characteristic leukodystrophy phenotype.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:36113749
      reference_title: "Galactosylceramidase deficiency and pathological abnormalities in cerebral white matter of Krabbe disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >
        Functional deficiency of GALC is toxic to myelin-producing cells, which
        leads to progressive demyelination in both the central and peripheral
        nervous systems.
      explanation: >
        This directly supports demyelination as the mechanism underlying
        Krabbe disease leukodystrophy.
  - target: Peripheral Neuropathy
    description: Peripheral demyelination causes the peripheral neuropathy phenotype.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:36113749
      reference_title: "Galactosylceramidase deficiency and pathological abnormalities in cerebral white matter of Krabbe disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >
        Functional deficiency of GALC is toxic to myelin-producing cells, which
        leads to progressive demyelination in both the central and peripheral
        nervous systems.
      explanation: >
        This directly supports peripheral demyelination as the basis of
        peripheral neuropathy in Krabbe disease.
  - target: Spasticity
    description: >
      Central motor-tract and white-matter demyelination contributes to
      early spasticity in infantile and later-onset Krabbe disease.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:32912261
      reference_title: "Natural history of Krabbe disease - a nationwide study in Germany using clinical and MRI data."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >
        Spasticity is a very early feature, appearing at or briefly after onset.
      explanation: >
        Natural-history data place spasticity early in the Krabbe disease
        course, downstream of the demyelinating leukodystrophy process.
  - target: Developmental Regression
    description: >
      Progressive CNS demyelination and neurodegeneration cause loss of
      acquired developmental milestones.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:32912261
      reference_title: "Natural history of Krabbe disease - a nationwide study in Germany using clinical and MRI data."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >
        Irritability, abnormalities in movement pattern as well as general
        developmental regression were the first symptoms in the infantile group
      explanation: >
        The infantile natural-history cohort identifies developmental
        regression as an early manifestation of the demyelinating disease
        trajectory.
  - target: Irritability in Infancy
    description: >
      Infantile Krabbe disease often first presents with irritability during
      the rapidly progressive neurodegenerative phase.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:32912261
      reference_title: "Natural history of Krabbe disease - a nationwide study in Germany using clinical and MRI data."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >
        Irritability, abnormalities in movement pattern as well as general
        developmental regression were the first symptoms in the infantile group
      explanation: >
        The cohort describes irritability as an early infantile symptom
        during the same rapidly progressive leukodystrophy course.
  - target: Seizures
    description: >
      Progressive CNS white-matter disease and neurodegeneration are
      associated with seizures during infantile Krabbe disease.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:10992329
      reference_title: "Krabbe disease--clinical profile."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >
        Most of the children with infantile disease presented with
        neurodegeneration, seizures or fever.
      explanation: >
        The clinical series links seizures to the infantile
        neurodegenerative Krabbe presentation.
  - target: Optic Atrophy
    description: >
      Visual pathway involvement during CNS demyelination can progress to
      optic atrophy in a subset of patients.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:10992329
      reference_title: "Krabbe disease--clinical profile."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >
        Optic atrophy was uncommon in our series (present only in a single case).
      explanation: >
        Although uncommon in this cohort, optic atrophy is documented as a
        Krabbe disease manifestation and is modeled downstream of CNS
        demyelinating visual-pathway involvement.
  - target: Feeding Difficulties
    description: >
      Progressive neurologic deterioration causes swallowing and feeding
      impairment, often requiring tube feeding in infantile disease.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:32912261
      reference_title: "Natural history of Krabbe disease - a nationwide study in Germany using clinical and MRI data."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >
        Severe swallowing problems necessitating tube feeding or PEG
        occurred on average 4 months after onset.
      explanation: >
        The natural-history cohort places severe swallowing and tube-feeding
        needs downstream in the infantile Krabbe disease course.
  evidence:
  - reference: PMID:36113749
    reference_title: "Galactosylceramidase deficiency and pathological abnormalities in cerebral white matter of Krabbe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      Functional deficiency of GALC is toxic to myelin-producing cells, which
      leads to progressive demyelination in both the central and peripheral
      nervous systems.
    explanation: >
      Neuropathological study of human Krabbe disease brains confirming
      progressive demyelination in CNS and PNS due to GALC deficiency.
- name: Cell-Autonomous Neuronal Toxicity
  description: >-
    Psychosine injures neurons directly, in parallel with rather than downstream
    of oligodendrocyte and Schwann cell death. Induced neurons converted from
    adult-onset Krabbe patient fibroblasts show neurite fragmentation and
    abnormal neuritic branching alongside the expected loss of GALC activity and
    rise in psychosine, and psychosine applied to neurons from healthy
    individuals is sufficient to reproduce those defects. In the twitcher mouse,
    psychosine concentrates in presynaptic membranes and synaptic vesicles, and
    hippocampal neurons show cell-autonomous reductions in paired-pulse
    facilitation and excitatory postsynaptic potential amplitude. This arm means
    Krabbe disease is not exclusively a disorder of myelinating glia, and it is
    one candidate explanation for why transplantation does not fully arrest
    progression.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  biological_processes:
  - preferred_term: neuron projection development
    term:
      id: GO:0031175
      label: neuron projection development
  - preferred_term: synaptic vesicle cycle
    term:
      id: GO:0099504
      label: synaptic vesicle cycle
  evidence:
  - reference: PMID:27780934
    reference_title: "Patient fibroblasts-derived induced neurons demonstrate autonomous neuronal defects in adult-onset Krabbe disease."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "directly converted KD iNeurons showed not only diminished GALC activity and increased psychosine levels, as expected, but also neurite fragmentation and abnormal neuritic branching"
    explanation: >-
      Neurons converted directly from the fibroblasts of two adult-onset Krabbe
      patients carry a neuronal phenotype in a system that contains no
      oligodendrocytes, so the defect cannot be secondary to demyelination.
      Scope caveat: both donors were adult-onset compound heterozygotes, so
      extrapolation to infantile disease is an inference.
  - reference: PMID:41430252
    reference_title: "Impaired docking and recycling of synaptic vesicles in inherited lysosomal sphingolipidoses."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "In vivo electrophysiological recording revealed significant cell autonomous reductions in paired-pulse facilitation and excitatory postsynaptic potential amplitude in hippocampal neurons of TWI mice."
    explanation: >-
      Extends the neuronal arm from morphology to function in vivo, and locates
      psychosine in the presynaptic compartment where the deficit is measured.
- name: GalCer-Driven Macrophage Pathology
  description: >-
    GALC-deficient macrophages cannot degrade galactosylceramide (GalCer);
    when exposed to GalCer they are transformed into globoid cells and
    drive a more severe phenotype, independent of psychosine-induced
    oligodendrocyte demyelination. This identifies a parallel disease arm
    driven by macrophage-autonomous GalCer storage and explains why HSCT
    (delivering healthy phagocytic macrophages) reduces nerve globoid
    cells without requiring efficient enzyme cross-correction.
  cell_types:
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  evidence:
  - reference: PMID:32375064
    reference_title: "Macrophages Expressing GALC Improve Peripheral Krabbe Disease by a Mechanism Independent of Cross-Correction."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "macrophages require GALC to degrade myelin, as Galc-deficient macrophages are transformed into globoid cells by exposure to galactosylceramide and produce a more severe GLD phenotype"
    explanation: >-
      Direct experimental demonstration that GalCer accumulation in
      GALC-deficient macrophages — independent of psychosine — drives
      globoid-cell transformation and exacerbates the GLD phenotype,
      supporting a parallel macrophage-autonomous arm of the canonical
      model.
  - reference: PMID:37337846
    reference_title: "Genetic ablation of Saposin-D in Krabbe disease eliminates psychosine accumulation but does not significantly improve demyelination."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Bone marrow-derived macrophages from both Twi and Twi/Sap-D KO mice produced significant amounts of TNF-α upon exposure to GalCer and were transformed into globoid cells"
    explanation: >-
      Independent corroboration of this arm from a different laboratory and a
      different genetic model. It carries extra weight because it comes from the
      study that eliminated psychosine: macrophages still became globoid cells
      and still released TNF-alpha on GalCer exposure, which is what the authors
      propose as the psychosine-independent route to the residual demyelination.
- name: Globoid Cell Accumulation
  description: >
    Multinucleated globoid macrophages accumulate in Krabbe disease white
    matter as a hallmark neuropathologic lesion.
  cell_types:
  - preferred_term: microglial cell
    term:
      id: CL:0000129
      label: microglial cell
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  evidence:
  - reference: PMID:36113749
    reference_title: "Galactosylceramidase deficiency and pathological abnormalities in cerebral white matter of Krabbe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      an early-infantile case (age of death at 10 months) had about 3-fold
      increases in both globoid cells, a pathological hallmark for KD
    explanation: >
      Quantifies the presence of globoid cells as a hallmark neuropathologic
      lesion in Krabbe disease.
- name: Microglial and Astrocyte Reactivity
  conforms_to: "cns_myelin_failure#Microglial Injury and Reactive Gliosis"
  description: >
    Krabbe disease triggers marked activation of microglia and astrocytes in
    affected white matter.
  cell_types:
  - preferred_term: microglial cell
    term:
      id: CL:0000129
      label: microglial cell
  - preferred_term: astrocyte
    term:
      id: CL:0000127
      label: astrocyte
  downstream:
  - target: Inflammasome Activation
    description: Activated glial cells participate in downstream inflammasome-related inflammatory signaling.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:36519759
      reference_title: "Upregulation of non-canonical and canonical inflammasome genes associates with pathological features in Krabbe disease and related disorders."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >
        Caspase-11 is found in reactive microglia/macrophages as well as
        astrocytes but caspase-1 and gasdermin D are restricted to reactive
        microglia/macrophages
      explanation: >
        This directly links reactive glial populations to inflammasome
        component expression in Krabbe disease tissue.
  evidence:
  - reference: PMID:37048066
    reference_title: "Rapamycin Alleviates Protein Aggregates, Reduces Neuroinflammation, and Rescues Demyelination in Globoid Cell Leukodystrophy."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >
      The astrocytes and microglia reactivity were attenuated in that reactive
      astrocytes, ameboid microglia, and globoid cells were reduced in the
      brains of rapamycin-treated twitcher mice
    explanation: >
      Demonstrates robust astrocyte and microglial reactivity in twitcher
      mouse brains, supporting a distinct glial-reactivity node.
- name: Inflammasome Activation
  description: >
    Non-canonical (caspase-11) and canonical (caspase-1) inflammasome
    pathways and gasdermin D are progressively induced in nervous tissue
    in Krabbe disease. Caspase-11 localizes to reactive microglia/macrophages
    and astrocytes, while caspase-1 and gasdermin D are restricted to
    reactive microglia/macrophages. This inflammasome signature accompanies
    demyelination and gliosis and may represent a therapeutic target.
  cell_types:
  - preferred_term: microglial cell
    term:
      id: CL:0000129
      label: microglial cell
  - preferred_term: astrocyte
    term:
      id: CL:0000127
      label: astrocyte
  biological_processes:
  - preferred_term: inflammatory response
    term:
      id: GO:0006954
      label: inflammatory response
  locations:
  - preferred_term: spinal cord
    term:
      id: UBERON:0002240
      label: spinal cord
  - preferred_term: brain white matter
    term:
      id: UBERON:0003544
      label: brain white matter
  evidence:
  - reference: PMID:36519759
    reference_title: "Upregulation of non-canonical and canonical inflammasome genes associates with pathological features in Krabbe disease and related disorders."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >
      the expression of pro-inflammatory non-canonical caspase-11, canonical
      caspase-1, gasdermin D and cognate genes is induced in nervous tissue
    explanation: >
      Establishes that inflammasome-associated genes including caspase-11,
      caspase-1, and gasdermin D are progressively induced in twitcher mouse
      nervous tissue, identifying a new pathogenic mechanism in Krabbe disease.
  - reference: PMID:36519759
    reference_title: "Upregulation of non-canonical and canonical inflammasome genes associates with pathological features in Krabbe disease and related disorders."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >
      Caspase-11 is found in reactive microglia/macrophages as well as
      astrocytes but caspase-1 and gasdermin D are restricted to reactive
      microglia/macrophages
    explanation: >
      Defines cell-type-specific expression patterns of inflammasome
      components in Krabbe disease nervous tissue.
- name: Proteostasis Failure
  conforms_to: "lysosomal_substrate_accumulation#Autophagic-Lysosomal Dysfunction and Secondary Cascade"
  description: >
    Psychosine causes dysfunction of autophagy and the ubiquitin-proteasome
    system, leading to accumulation of insoluble ubiquitinated protein
    aggregates in the brain. This proteostasis failure contributes to
    neurodegeneration and can be partially rescued by mTOR inhibition
    with rapamycin.
  biological_processes:
  - preferred_term: autophagy
    term:
      id: GO:0006914
      label: autophagy
  locations:
  - preferred_term: brain white matter
    term:
      id: UBERON:0003544
      label: brain white matter
  downstream:
  - target: Microglial and Astrocyte Reactivity
    description: >
      Psychosine-driven proteostasis failure contributes to neuroinflammatory
      glial reactivity; reducing aggregate burden attenuates reactive
      astrocytes and ameboid microglia in the twitcher model.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:37048066
      reference_title: "Rapamycin Alleviates Protein Aggregates, Reduces Neuroinflammation, and Rescues Demyelination in Globoid Cell Leukodystrophy."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >
        Administration of rapamycin to twitcher mice inhibited mTOR signaling
        in the brains, and significantly reduced the accumulation of insoluble
        ubiquitinated protein and the formation of ubiquitin aggregates. The
        astrocytes and microglia reactivity were attenuated in that reactive
        astrocytes, ameboid microglia, and globoid cells were reduced in the
        brains of rapamycin-treated twitcher mice.
      explanation: >
        In the twitcher mouse model, lowering the proteostasis/aggregate
        burden is accompanied by reduced astrocyte and microglial
        reactivity, supporting an indirect connection from proteostasis
        failure to neuroinflammatory glial activation.
  evidence:
  - reference: PMID:37048066
    reference_title: "Rapamycin Alleviates Protein Aggregates, Reduces Neuroinflammation, and Rescues Demyelination in Globoid Cell Leukodystrophy."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >
      psychosine causes dysfunction of autophagy and the ubiquitin-proteasome
      system underlying the pathogenesis of globoid cell leukodystrophy (GLD),
      a devastating lysosomal storage disease complicated by global demyelination
    explanation: >
      Establishes that psychosine-driven proteostasis failure through
      autophagy and UPS dysfunction is a key pathogenic mechanism in
      globoid cell leukodystrophy.
  - reference: PMID:37048066
    reference_title: "Rapamycin Alleviates Protein Aggregates, Reduces Neuroinflammation, and Rescues Demyelination in Globoid Cell Leukodystrophy."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >
      significantly reduced the accumulation of insoluble ubiquitinated protein
      and the formation of ubiquitin aggregates
    explanation: >
      Demonstrates that mTOR inhibition with rapamycin can reduce protein
      aggregate burden in twitcher mouse brains, validating proteostasis
      failure as a tractable therapeutic target.
- name: Adaptive Immune Cell Infiltration
  description: >-
    Beyond innate microglial and astrocytic activation, Krabbe disease white
    matter shows infiltration of CD8-positive T lymphocytes, an adaptive
    immune component whose burden tracks with clinical severity and
    neuropathology (greater in a more rapidly fatal early-infantile case than
    in a slower-progressing infantile case). This extends the Krabbe
    neuroinflammatory picture beyond the innate arm to include adaptive
    immunity.
  cell_types:
  - preferred_term: CD8-positive T lymphocyte
    term:
      id: CL:0000625
      label: CD8-positive, alpha-beta T cell
  biological_processes:
  - preferred_term: adaptive immune response
    term:
      id: GO:0002250
      label: adaptive immune response
  locations:
  - preferred_term: brain white matter
    term:
      id: UBERON:0003544
      label: brain white matter
  evidence:
  - reference: PMID:36113749
    reference_title: "Galactosylceramidase deficiency and pathological abnormalities in cerebral white matter of Krabbe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      increases in both globoid cells, a pathological hallmark for KD, and
      CD8-positive T lymphocytes, a pathological marker for multiple sclerosis,
      in the white matter
    explanation: >-
      Human Krabbe disease brain neuropathology identifies CD8-positive T
      lymphocyte infiltration in white matter, with greater burden in the more
      severe early-infantile case, evidencing an adaptive immune contribution
      to the disease that correlates with clinical severity.
phenotypes:
- category: Neurologic
  name: Leukodystrophy
  description: >
    Progressive white matter degeneration visible on MRI as symmetric
    signal abnormalities in cerebral white matter, with eventual atrophy.
  phenotype_term:
    preferred_term: Leukodystrophy
    term:
      id: HP:0002415
      label: Leukodystrophy
  evidence:
  - reference: PMID:32912261
    reference_title: "Natural history of Krabbe disease - a nationwide study in Germany using clinical and MRI data."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      The different forms of the disease were characterized by different MRI
      patterns (infantile: diffuse white matter involvement and cerebellar
      structures specifically affected, later onset: parieto-occipital white
      matter and splenium affected, adult: motor tracts specifically affected).
    explanation: >
      This natural history study directly documents characteristic
      white-matter MRI abnormalities across Krabbe disease forms, supporting
      leukodystrophy as an observed phenotype.
- category: Neurologic
  name: Spasticity
  description: >
    Progressive increase in muscle tone due to upper motor neuron
    involvement from white matter destruction.
  phenotype_term:
    preferred_term: Spasticity
    term:
      id: HP:0001257
      label: Spasticity
  evidence:
  - reference: PMID:32912261
    reference_title: "Natural history of Krabbe disease - a nationwide study in Germany using clinical and MRI data."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      Developmental and disease trajectories were described based on the
      acquisition and loss of milestones as well as the time of first clearly
      identifiable symptoms and needs such as spasticity, seizures and tube
      feeding.
    explanation: >
      This natural history study directly identifies spasticity as a tracked
      neurological manifestation in Krabbe disease, providing more specific
      support than generic motor-delay language.
- category: Neurologic
  name: Peripheral Neuropathy
  description: >
    Demyelinating peripheral neuropathy due to Schwann cell loss,
    manifesting as hyporeflexia and reduced nerve conduction velocities.
  phenotype_term:
    preferred_term: Peripheral demyelinating neuropathy
    term:
      id: HP:0007108
      label: Demyelinating peripheral neuropathy
  evidence:
  - reference: PMID:36113749
    reference_title: "Galactosylceramidase deficiency and pathological abnormalities in cerebral white matter of Krabbe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      Functional deficiency of GALC is toxic to myelin-producing cells, which
      leads to progressive demyelination in both the central and peripheral
      nervous systems.
    explanation: >
      Confirms peripheral nervous system demyelination as a feature of Krabbe
      disease due to toxicity to Schwann cells, the myelin-producing cells
      of the PNS.
- category: Neurologic
  name: Irritability in Infancy
  description: >
    Extreme irritability is often the earliest clinical feature in
    infantile Krabbe disease, frequently preceding other neurological signs.
  phenotype_term:
    preferred_term: Irritability
    term:
      id: HP:0000737
      label: Irritability
  evidence:
  - reference: PMID:32912261
    reference_title: "Natural history of Krabbe disease - a nationwide study in Germany using clinical and MRI data."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      Irritability, abnormalities in movement pattern as well as general
      developmental regression were the first symptoms in the infantile group
    explanation: >
      This natural history study directly identifies irritability as one of
      the first symptoms in infantile Krabbe disease.
- category: Neurologic
  name: Seizures
  description: >
    Seizures occur in Krabbe disease, particularly in advanced stages.
    Uncontrolled seizures are a frequent terminal event in infantile
    Krabbe disease.
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:10992329
    reference_title: "Krabbe disease--clinical profile."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      Most of the children with infantile disease presented with
      neurodegeneration, seizures or fever
    explanation: >
      Clinical series of nine children with enzymatically confirmed Krabbe
      disease documents seizures as a presenting feature in infantile KD.
- category: Neurologic
  name: Developmental Regression
  description: >
    Loss of previously acquired developmental milestones is a hallmark
    of infantile Krabbe disease, with progressive loss of motor and
    cognitive skills following initial normal development.
  phenotype_term:
    preferred_term: Developmental regression
    term:
      id: HP:0002376
      label: Developmental regression
  evidence:
  - reference: PMID:32912261
    reference_title: "Natural history of Krabbe disease - a nationwide study in Germany using clinical and MRI data."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      Irritability, abnormalities in movement pattern as well as general
      developmental regression were the first symptoms in the infantile group
    explanation: >
      Nationwide German natural history study of 38 Krabbe patients documents
      developmental regression as a frequent first symptom in infantile KD.
- category: Neurologic
  name: Optic Atrophy
  description: >
    Progressive optic nerve demyelination leads to optic atrophy and
    visual impairment, particularly in infantile Krabbe disease.
  phenotype_term:
    preferred_term: Optic atrophy
    term:
      id: HP:0000648
      label: Optic atrophy
  evidence:
  - reference: PMID:10992329
    reference_title: "Krabbe disease--clinical profile."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      Optic atrophy was uncommon in our series (present only in a single case).
    explanation: >
      This enzymatically confirmed pediatric Krabbe disease series documents
      optic atrophy in one patient.
- category: Neurologic
  name: Feeding Difficulties
  description: >
    Difficulty with feeding due to bulbar dysfunction and progressive
    neurological deterioration, often requiring tube feeding in infantile
    Krabbe disease.
  phenotype_term:
    preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  evidence:
  - reference: PMID:32912261
    reference_title: "Natural history of Krabbe disease - a nationwide study in Germany using clinical and MRI data."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      Irritability, abnormalities in movement pattern as well as general
      developmental regression were the first symptoms in the infantile group;
      disease course was severe with rapid progression, e.g. loss of visual
      fixation, need for tube feeding and then an early death.
    explanation: >
      This natural history study supports clinically significant feeding
      dysfunction in infantile Krabbe disease through the frequent need for
      tube feeding during rapid progression.
biochemical:
- name: Psychosine (Galactosylsphingosine)
  biomarker_term:
    preferred_term: psychosine
    term:
      id: CHEBI:16874
      label: psychosine
  presence: Elevated
  context: >
    Key toxic metabolite and biomarker. Blood psychosine levels used
    for newborn screening second-tier testing. Infantile KD typically
    shows levels >=10 nM; late-infantile KD shows 2-10 nM.
  loinc_term:
    id: LOINC:LP411706-7
    label: Psychosine
  notes: >-
    The marker is described as a blood measurement used both for diagnosis and
    for the newborn-screening second tier, and LOINC codes psychosine in dried
    blood spot, cerebrospinal fluid and red blood cells rather than in blood,
    so loinc_term binds the specimen-agnostic LOINC Part; the DBS quantitative
    code and its cut-off sit on the newborn-screening diagnosis row, where the
    specimen is intrinsic to the test.
  readouts:
  - target: Psychosine Accumulation
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: >
      Elevated psychosine reports the proximal toxic sphingolipid storage
      abnormality caused by GALC deficiency.
    evidence:
    - reference: PMID:20301416
      reference_title: Krabbe Disease.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >
        elevated psychosine levels can also help establish the diagnosis.
      explanation: >
        GeneReviews identifies elevated psychosine as a diagnostic marker
        for Krabbe disease.
  evidence:
  - reference: PMID:31527255
    reference_title: "Genetic ablation of acid ceramidase in Krabbe disease confirms the psychosine hypothesis and identifies a new therapeutic target."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >
      GALC deficiency leads to the accumulation of the cytotoxic glycolipid,
      galactosylsphingosine (psychosine)
    explanation: >
      Confirms psychosine accumulation as the primary biochemical
      abnormality in Krabbe disease due to GALC deficiency.
  - reference: PMID:38390974
    reference_title: "Newborn Screening for Krabbe Disease: Status Quo and Recommendations for Improvements."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      a two-tiered strategy based on psychosine (PSY) as the determinant if
      an NBS result is positive or negative after a first-tier test revealed
      decreased galactocerebrosidase activity
    explanation: >
      Psychosine is used as a second-tier newborn screening biomarker,
      confirming its diagnostic utility as an elevated metabolite in
      Krabbe disease.
- name: GALC Enzyme Activity
  presence: Reduced
  context: >
    Galactosylceramidase enzyme activity is deficient in all forms of
    Krabbe disease. Measured in leukocytes or dried blood spots as
    the first-tier newborn screening test.
  loinc_term:
    id: LOINC:LP14027-4
    label: Galactosylceramidase
  notes: >-
    The marker is described in leukocytes and in the newborn-screening dried
    blood spot alike, so loinc_term binds the specimen-agnostic LOINC Part;
    the DBS quantitative code sits on the newborn-screening diagnosis row,
    where the specimen is intrinsic to the test.
  readouts:
  - target: GALC Deficiency
    relationship: READOUT_OF
    direction: NEGATIVE
    endpoint_context: DIAGNOSTIC
    interpretation: >
      Low leukocyte or dried-blood-spot GALC enzyme activity directly reports
      the initiating galactosylceramidase deficiency.
    evidence:
    - reference: PMID:20301416
      reference_title: Krabbe Disease.
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >
        established by detection of deficient GALC enzyme activity in leukocytes.
      explanation: >
        GeneReviews identifies deficient leukocyte GALC enzyme activity as
        the diagnostic biochemical readout.
  evidence:
  - reference: PMID:36113749
    reference_title: "Galactosylceramidase deficiency and pathological abnormalities in cerebral white matter of Krabbe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      homozygous null mutations in GALC lead to deficiency in total GALC
      protein and activity
    explanation: >
      Confirms that null GALC mutations lead to complete deficiency in
      GALC protein and enzyme activity in infantile Krabbe disease brains.
genetic:
- name: GALC
  gene_term:
    preferred_term: GALC
    term:
      id: hgnc:4115
      label: GALC
  association: Pathogenic Mutations
  presence: Positive
  notes: >
    Krabbe disease is caused by biallelic loss-of-function mutations in
    GALC (14q31.3), encoding galactosylceramidase. Over 200 pathogenic
    variants have been identified. The most common mutation in patients
    of European descent is a ~30 kb deletion starting at intron 10.
  inheritance:
  - name: Autosomal Recessive
  variants:
  - name: 30-kb deletion (intron 10-17)
    description: >
      Large deletion encompassing exons 11-17, the most common
      pathogenic variant in European populations.
  evidence:
  - reference: PMID:8634707
    reference_title: "Characterization of the large deletion in the GALC gene found in patients with Krabbe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      the deletion is approximately 30 kb starting near the middle of the
      12 kb intron 10, and includes all of the coding region through exon 17
      plus an additional 9 kb
    explanation: >
      Characterizes the large ~30 kb deletion in the GALC gene, one of the
      most common mutations causing infantile Krabbe disease.
  - reference: PMID:7581365
    reference_title: "A large deletion together with a point mutation in the GALC gene is a common mutant allele in patients with infantile Krabbe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      a large deletion, together with a polymorphic C to T transition at
      position 502 of cDNA (counting from the A of the initiation codon), is
      responsible for a large number of disease-causing alleles in patients
      with Krabbe disease
    explanation: >
      Demonstrates that the large deletion plus 502C>T polymorphism is a
      common mutant allele in infantile Krabbe disease, found in homozygous
      or heterozygous state in the majority of patients tested.
  - reference: PMID:36113749
    reference_title: "Galactosylceramidase deficiency and pathological abnormalities in cerebral white matter of Krabbe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      Krabbe Disease (KD) is an autosomal recessive disorder that results from
      loss-of-function mutations in the GALC gene, which encodes lysosomal
      enzyme galactosylceramidase (GALC).
    explanation: >
      Confirms autosomal recessive inheritance and GALC loss-of-function
      as the genetic basis of Krabbe disease.
  - reference: CGGV:assertion_d17202fb-89c4-4bf6-ad57-4b8c541dc808-2022-06-15T160000.000Z
    reference_title: "GALC / Krabbe disease (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "GALC | HGNC:4115 | Krabbe disease | MONDO:0009499 | AR | Definitive"
    explanation: ClinGen classifies the GALC-Krabbe disease gene-disease relationship as definitive with autosomal recessive inheritance.
diagnosis:
- name: Newborn Screening
  description: >
    Two-tiered newborn screening strategy using GALC enzyme activity as
    first-tier test on dried blood spots, followed by psychosine measurement
    as second-tier determinant. Krabbe disease is part of newborn screening
    in 11 US states.
  diagnosis_term:
    preferred_term: newborn screening
    term:
      id: NCIT:C81178
      label: Newborn Screening
  measurements:
  - preferred_term: galactocerebrosidase (GALC) activity, DBS
    term:
      id: LOINC:62310-8
      label: Galactosylceramidase [Enzymatic activity/volume] in DBS
  - preferred_term: psychosine, DBS (second tier)
    term:
      id: LOINC:93688-0
      label: Psychosine [Moles/volume] in DBS
  reference_ranges:
  - loinc_term:
      id: LOINC:93688-0
      label: Psychosine [Moles/volume] in DBS
    unit: nmol/L
    population: >-
      newborn screening, Illinois (USA) programme, 8 December 2017 to 31
      December 2020; second-tier psychosine on specimens with low GALC
      activity, cut-off of the reference laboratory that ran the assay
    notes: >-
      The source writes the unit as nM; nmol/L is the UCUM spelling of the
      same unit, not a conversion. The programme states the abnormal rule as
      psychosine "greater than or equal to 8.7 nM", so the inclusive lower
      bound of the top band matches the source exactly. The intermediate tier
      is written ">2-<8.7 nM" and the negative tier "<2.0 nM", so the source
      assigns exactly 2.0 to neither; the half-open convention puts it in the
      intermediate band. The intermediate tier is not a referral rule on its
      own: the programme followed those infants only when GALC sequencing
      found pathogenic variants. The same paper says the laboratory was
      updating its psychosine cut-off to 10 nM to agree with other testing
      laboratories, so 8.7 is recorded as the cited period's value and not as a
      property of the analyte.
    evidence:
    - reference: PMID:34065072
      reference_title: "Newborn Screening for Krabbe Disease-Illinois Experience: Role of Psychosine in Diagnosis of the Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Abnormal PSY level (greater than or equal to 8.7 nM; PerkinElmer Genetics, Inc., Pittsburg, PA, USA) and/or detection of a homozygous 30-kb deletion triggered immediate referral to a consultant/specialized center for the purpose of evaluation for HSCT"
      explanation: States the dried-blood-spot psychosine threshold at which the Illinois programme referred a newborn immediately for infantile Krabbe disease evaluation.
    - reference: PMID:34065072
      reference_title: "Newborn Screening for Krabbe Disease-Illinois Experience: Role of Psychosine in Diagnosis of the Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "an intermediate group of infants who had mildly elevated PSY (>2–<8.7 nM) in the newborn screen specimen and had two pathogenic mutations were followed up regularly due to high risk for late-onset disease"
      explanation: Defines the intermediate psychosine tier and the genotype condition attached to following it up for later-onset disease.
    - reference: PMID:34065072
      reference_title: "Newborn Screening for Krabbe Disease-Illinois Experience: Role of Psychosine in Diagnosis of the Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "For the negative category, all specimens had negative/normal PSY levels (<2.0 nM), and the GALC gene sequencing revealed the presence of pseudodeficiency alleles."
      explanation: States the psychosine level the programme treated as negative, which is the open-below band.
    - reference: PMID:34065072
      reference_title: "Newborn Screening for Krabbe Disease-Illinois Experience: Role of Psychosine in Diagnosis of the Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "We are in the process of updating the PSY cut-off (to 10 nM) to reflect an agreed value among the testing/reference laboratories."
      explanation: Shows the referral cut-off was being revised, which is why the 8.7 figure is attributed to the cited period rather than stated as a fixed threshold.
    interpretation_bands:
    - name: Negative psychosine
      upper_bound: 2.0
      unit: nmol/L
      abnormal_flag: NORMAL
      interpretation: >-
        In this programme the low-GALC specimens with psychosine in this tier
        carried pseudodeficiency alleles, a single pathogenic variant or a
        variant of uncertain significance, and no follow-up was recommended.
    - name: Intermediate psychosine
      lower_bound: 2.0
      upper_bound: 8.7
      unit: nmol/L
      abnormal_flag: HIGH
      interpretation: >-
        Mildly elevated; infants in this tier whose GALC sequencing showed two
        pathogenic variants were followed as suspected late-onset Krabbe
        disease rather than referred for transplant evaluation.
    - name: Abnormal psychosine, immediate referral
      lower_bound: 8.7
      unit: nmol/L
      abnormal_flag: HIGH
      interpretation: >-
        Triggered immediate referral for evaluation for hematopoietic stem cell
        transplantation as presumptive infantile Krabbe disease; the two
        infantile cases the programme found had psychosine of 10 and 35 nM.
  notes: >-
    Measurements bind the method-less quantitative DBS codes; the specimen is
    intrinsic to a newborn screen, so the DBS code is the test's identity here
    rather than a method-specific variant. The first-tier GALC activity carries
    no band because the cited programmes state the rule as a fraction of the
    run's own median or mean rather than in the code's unit: Illinois repeated
    any specimen at or below 16% of the batch median and called a screen
    positive at or below 13% of the batch median; New York State sent specimens
    at or below 12% of the daily mean to molecular analysis. A percentage of a
    batch statistic cannot be carried as a band on an activity-per-volume code,
    so those rules are recorded as evidence here instead. The Illinois paper
    states its repeat trigger inclusively in its methods and call-out table
    ("less than or equal to 16%", "≤16") and once as "<16%" in its discussion;
    the quoted methods wording is the one recorded. The psychosine cut-off is
    programme- and laboratory-specific and is recorded as the cited period's
    value; the same paper's table footnote gives the complementary statement
    "PSY normal range < 8.7 nM", which agrees with the quoted rule.
  evidence:
  - reference: PMID:34065072
    reference_title: "Newborn Screening for Krabbe Disease-Illinois Experience: Role of Psychosine in Diagnosis of the Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "An initial screen for GALC was performed in a single punch, and if the GALC activity was less than or equal to 16% of the batch median, the analysis was repeated in five replications. A positive GALC screen was defined as a mean of repeated activity of less than or equal to 13% of the batch median."
    explanation: States the Illinois first-tier GALC activity rule as a percentage of the batch median, which is why the GALC measurement carries no numeric band.
  - reference: PMID:26795590
    reference_title: "Newborn screening for Krabbe disease in New York State: the first eight years' experience."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Dried blood spots from newborns were assayed for GALC enzyme activity using mass spectrometry, followed by molecular analysis for those with low activity (≤12% of the daily mean)."
    explanation: States the New York State first-tier GALC rule, again as a percentage of the run's mean, and documents the dried-blood-spot GALC activity measurement bound here.
  - reference: PMID:34065072
    reference_title: "Newborn Screening for Krabbe Disease-Illinois Experience: Role of Psychosine in Diagnosis of the Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Our data show that a high percentage of reduced GALC activity (62%) was due to the presence of pseudodeficiency alleles in the GALC gene."
    explanation: Shows that a low first-tier GALC activity is mostly produced by pseudodeficiency rather than disease, which is why the second-tier psychosine measurement is bound beside it.
  - reference: PMID:38390974
    reference_title: "Newborn Screening for Krabbe Disease: Status Quo and Recommendations for Improvements."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      Krabbe disease (KD) is part of newborn screening (NBS) in 11 states with
      at least one additional state preparing to screen
    explanation: >
      Documents the current status of newborn screening programs for Krabbe
      disease across US states, with psychosine as a key second-tier biomarker.
  - reference: PMID:38390974
    reference_title: "Newborn Screening for Krabbe Disease: Status Quo and Recommendations for Improvements."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      when modeling the data based on the recommended screening strategy for
      KD, and applying different cutoffs for PSY, each state could virtually
      eliminate false positive results without major impact on sensitivity
    explanation: >
      Demonstrates that psychosine-based second-tier screening can virtually
      eliminate false positives while maintaining sensitivity for infantile
      Krabbe disease detection.
- name: GALC Enzyme Activity Assay
  description: >
    Measurement of galactosylceramidase activity in leukocytes or fibroblasts.
    Deficient activity confirms the diagnosis, though pseudodeficiency alleles
    can complicate interpretation.
  evidence:
  - reference: PMID:36113749
    reference_title: "Galactosylceramidase deficiency and pathological abnormalities in cerebral white matter of Krabbe disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      homozygous null mutations in GALC lead to deficiency in total GALC
      protein and activity
    explanation: >
      Demonstrates that GALC protein and enzyme activity measurement can
      distinguish infantile Krabbe disease cases with null mutations.
treatments:
- name: Hematopoietic Stem Cell Transplantation
  description: >
    HSCT is the only treatment shown to alter disease course when performed
    presymptomatically in infantile Krabbe disease or early in later-onset
    forms. It provides donor-derived enzyme to the CNS via engrafted
    microglia. For infantile KD, transplantation must occur within the
    first 30-45 days of life to be effective.
  therapeutic_modality: CELL_THERAPY
  treatment_term:
    preferred_term: hematopoietic stem cell transplantation
    term:
      id: NCIT:C15431
      label: Hematopoietic Cell Transplantation
  target_mechanisms:
  - target: GALC Deficiency
    treatment_effect: RESTORES
    description: >
      Donor-derived hematopoietic cells restore galactocerebrosidase activity
      in blood after successful engraftment.
    evidence:
    - reference: PMID:15901860
      reference_title: "Transplantation of umbilical-cord blood in babies with infantile Krabbe's disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >
        Surviving patients showed durable engraftment of donor-derived
        hematopoietic cells with restoration of normal blood
        galactocerebrosidase levels.
      explanation: >
        The cord-blood transplantation study directly supports restoration
        of the deficient enzyme activity after donor-cell engraftment.
  - target: Demyelination
    treatment_effect: MODULATES
    description: >
      Presymptomatic transplantation can permit progressive central
      myelination and alter the infantile disease trajectory.
    evidence:
    - reference: PMID:15901860
      reference_title: "Transplantation of umbilical-cord blood in babies with infantile Krabbe's disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >
        Infants who underwent transplantation before the development of
        symptoms showed progressive central myelination and continued gains
        in developmental skills
      explanation: >
        Presymptomatic cord-blood transplantation is associated with
        continued myelination, supporting a disease-modifying effect on
        the demyelination pathway.
  evidence:
  - reference: PMID:15901860
    reference_title: "Transplantation of umbilical-cord blood in babies with infantile Krabbe's disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      Infants who underwent transplantation before the development of symptoms
      showed progressive central myelination and continued gains in
      developmental skills, and most had age-appropriate cognitive function and
      receptive language skills
    explanation: >
      Landmark NEJM study demonstrating that presymptomatic cord blood
      transplantation favorably alters disease course in infantile Krabbe
      disease with continued myelination and developmental gains.
  - reference: PMID:15901860
    reference_title: "Transplantation of umbilical-cord blood in babies with infantile Krabbe's disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >
      Children who underwent transplantation after the onset of symptoms had
      minimal neurologic improvement.
    explanation: >
      Demonstrates that HSCT after symptom onset has minimal benefit,
      underscoring the critical importance of early/presymptomatic treatment.
- name: Gene Therapy (Investigational)
  description: >
    AAV-mediated gene therapy to restore GALC expression is under active
    investigation. Preclinical studies in mouse and canine models show
    that CNS-directed AAV-GALC can normalize psychosine and extend
    survival. Combination of systemic AAV gene therapy with HSCT has
    shown the most promising results in canine models, with clinical
    trials underway (NCT04693598, NCT05739643).
  therapeutic_modality: GENE_THERAPY
  treatment_term:
    preferred_term: gene therapy
    term:
      id: NCIT:C15238
      label: Gene Therapy
  target_mechanisms:
  - target: GALC Deficiency
    treatment_effect: RESTORES
    description: >
      AAV-GALC therapy is designed to restore GALC expression in the CNS.
    evidence:
    - reference: PMID:37628569
      reference_title: "Brain Targeted AAV1-GALC Gene Therapy Reduces Psychosine and Extends Lifespan in a Mouse Model of Krabbe Disease."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >
        To rescue GALC gene function in the CNS of the twitcher mouse model
        of KD, an adeno-associated virus serotype 1 vector expressing
        murine GALC under control of a chicken β-actin promoter (AAV1-GALC)
        was administered to newborn mice
      explanation: >
        The preclinical study explicitly frames AAV1-GALC as restoring GALC
        gene function in the CNS.
  - target: Psychosine Accumulation
    treatment_effect: INHIBITS
    description: >
      CNS-directed AAV-GALC lowers or normalizes psychosine accumulation in
      treated twitcher mice.
    evidence:
    - reference: PMID:37628569
      reference_title: "Brain Targeted AAV1-GALC Gene Therapy Reduces Psychosine and Extends Lifespan in a Mouse Model of Krabbe Disease."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >
        Functionally, elevated levels of psychosine were completely
        normalized in the forebrain region of the treated mice.
      explanation: >
        Treated twitcher mice show normalization of elevated psychosine in
        forebrain, supporting psychosine lowering as a target effect.
  evidence:
  - reference: PMID:37628569
    reference_title: "Brain Targeted AAV1-GALC Gene Therapy Reduces Psychosine and Extends Lifespan in a Mouse Model of Krabbe Disease."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >
      elevated levels of psychosine were completely normalized in the forebrain
      region of the treated mice
    explanation: >
      AAV1-GALC gene therapy delivered via intracerebroventricular injection
      normalized psychosine in the forebrain and extended median lifespan
      from 43 to 78 days in the twitcher mouse model.
  - reference: PMID:37628569
    reference_title: "Brain Targeted AAV1-GALC Gene Therapy Reduces Psychosine and Extends Lifespan in a Mouse Model of Krabbe Disease."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >
      The median lifespan was extended from 43 days to 78 days (range: 74-88
      days) in the AAV1-GALC-treated group
    explanation: >
      Demonstrates significant survival extension with CNS-directed
      AAV1-GALC gene therapy in the twitcher mouse model.
- name: Supportive Care
  description: >
    Symptomatic management including physical therapy, antispasmodics,
    nutritional support, and seizure management.
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_phenotypes:
  - preferred_term: Spasticity
    term:
      id: HP:0001257
      label: Spasticity
  - preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:20301416
    reference_title: Krabbe Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >
      Treatment of a child who is symptomatic before age six months is
      supportive and focused on increasing the quality of life and avoiding
      complications.
    explanation: >
      GeneReviews supports supportive care for symptomatic early infantile
      Krabbe disease, which is represented as addressing the major
      symptomatic neurologic complications.
- name: Avoidance of disease-accelerating agents
  description: >
    GeneReviews lists atypical antipsychotics, multi-drug seizure regimens
    that cause over-sedation, and routine childhood vaccinations as
    agents/circumstances to avoid because they can affect cognition,
    respiratory drive, neurologic decline, or disease progression.
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_phenotypes:
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:20301416
    reference_title: Krabbe Disease.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >
      Agents/circumstances to avoid: Atypical antipsychotics and multiple
      medications for seizures can cause over-sedation (affecting cognition,
      respiratory drive, and rate of neurologic decline). Routine childhood
      vaccinations can accelerate disease progression.
    explanation: >
      GeneReviews explicitly identifies medication over-sedation risks and
      routine childhood vaccinations as agents or circumstances to avoid in
      Krabbe disease management.
- name: Substrate Reduction Therapy (Investigational)
  description: >-
    Because psychosine is generated catabolically by acid ceramidase (ACDase)
    deacylating galactosylceramide, ACDase inhibition is an emerging substrate
    reduction strategy that uncouples GALC deficiency from psychosine synthesis.
    Genetic ablation of ACDase in the twitcher mouse eliminates psychosine
    accumulation and rescues the phenotype, and pharmacological ACDase
    inhibition with carmofur lowers psychosine and extends twitcher lifespan.
    This approach is preclinical/investigational.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: carmofur
      term:
        id: CHEBI:31360
        label: Carmofur
  target_mechanisms:
  - target: Psychosine Accumulation
    treatment_effect: INHIBITS
    description: >-
      Acid ceramidase inhibition uncouples GALC deficiency from psychosine
      biogenesis, lowering the toxic storage metabolite.
    evidence:
    - reference: PMID:31527255
      reference_title: "Genetic ablation of acid ceramidase in Krabbe disease confirms the psychosine hypothesis and identifies a new therapeutic target."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >
        pharmacological inhibition of ACDase activity with carmofur
        significantly decreases psychosine accumulation in cells from a Krabbe
        patient and prolongs the life span of the twitcher (Twi) mouse
      explanation: >-
        Carmofur, an acid ceramidase inhibitor, decreases psychosine and
        extends survival in the twitcher model, supporting substrate reduction
        therapy targeting psychosine biogenesis.
  evidence:
  - reference: PMID:31527255
    reference_title: "Genetic ablation of acid ceramidase in Krabbe disease confirms the psychosine hypothesis and identifies a new therapeutic target."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >
      genetic loss of ACDase activity (Farber disease) in the GALC-deficient
      mouse model of human GLD (twitcher) eliminates psychosine accumulation
      and cures GLD
    explanation: >-
      Genetic ablation of acid ceramidase in twitcher mice eliminates
      psychosine accumulation and rescues the phenotype, providing proof of
      concept for substrate reduction therapy in Krabbe disease.
datasets:
- accession: metabolomics_workbench:ST000352
  title: Metabolic profiling reveals biochemical pathways and potential biomarkers associated with the pathogenesis of Krabbe disease
  notes: Located via OmicsDI, which aggregates across omics repositories; this record comes from metabolomics_workbench. Only repositories with no other discovery route in this project and with a working accession resolver are curated from OmicsDI -- GEO, ArrayExpress, PRIDE, MetaboLights and EGA hits are excluded as duplicates of dedicated passes. Matched because the disease is named in the dataset's own title ("Krabbe Disease"). Retrieved 2026-08-02.
discussions:
- discussion_id: gap_krabbe_psychosine_depletion_discordance
  prompt: >-
    Why do three independent ways of removing psychosine from the twitcher mouse
    give three different outcomes, and which non-psychosine product of GALC
    activity accounts for the demyelination that survives psychosine
    elimination?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - mechanistic_hypotheses#canonical_galc_deficiency_psychosine_demyelination_model
  - pathophysiology#Psychosine Accumulation
  - pathophysiology#Demyelination
  - pathophysiology#GalCer-Driven Macrophage Pathology
  rationale: >-
    Acid ceramidase ablation eliminates psychosine and rescues the twitcher
    phenotype, but saposin-D ablation also eliminates psychosine while leaving
    late-stage demyelination intact and shortening lifespan, and a UGT8
    inhibitor cuts psychosine 72-86% without changing survival. The three
    results cannot all be explained by psychosine being the operative toxin, so
    the sufficiency half of the canonical model is unsettled even though its
    upstream half is quantitatively validated. This is not a bookkeeping
    detail: whether a psychosine-lowering drug can work as monotherapy depends
    on the answer, and substrate reduction therapy is already curated in this
    entry as an investigational strategy aimed at psychosine biogenesis. No
    head-to-head comparison of the two knockout crosses exists; the three
    studies used different genetic backgrounds, endpoints, and time points, so
    the discordance may be partly methodological.
  proposed_experiments:
  - experiment_id: exp_krabbe_matched_background_sphingolipidomic_comparison
    name: Matched-background lipidomic comparison of psychosine-null twitcher crosses
    description: >-
      Generate ACDase-knockout and saposin-D-knockout twitcher crosses on one
      congenic background and profile brain, spinal cord, and sciatic nerve at
      matched pre-symptomatic, early, and late time points. Quantify the full
      sphingolipid panel, not psychosine alone, so that species differing
      between a rescued and an unrescued psychosine-null animal can be
      identified. Score demyelination, globoid cell burden, and survival in the
      same animals.
    experiment_type:
      preferred_term: comparative mass-spectrometry lipidomics of matched mouse crosses
    decision_criterion: >-
      A non-psychosine lipid that tracks with rescue across the two crosses
      nominates the missing toxic species and would justify a distinct
      pathophysiology node. If the two crosses are lipidomically
      indistinguishable, the discordance is not metabolic and attention should
      move to the macrophage and saposin-D-dependent arms.
    would_support:
    - pathophysiology#GalCer-Driven Macrophage Pathology
    supporting_outcome:
    - >-
        Galactosylceramide or another GALC substrate remains elevated in the
        unrescued psychosine-null cross and tracks with globoid cell burden and
        demyelination severity.
    refuting_outcome:
    - >-
        Both psychosine-null crosses show the same lipid profile and the same
        demyelination, which would place the difference outside sphingolipid
        metabolism altogether.
  evidence:
  - reference: PMID:37337846
    reference_title: "Genetic ablation of Saposin-D in Krabbe disease eliminates psychosine accumulation but does not significantly improve demyelination."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "The demyelination observed in Twi/Sap-D KO mice may be mediated by a psychosine-independent, Sap-D-dependent mechanism"
    explanation: >-
      The authors state the gap in their own terms: a psychosine-independent
      mechanism is required to account for the demyelination they observe, and
      they do not identify it.
  - reference: PMID:35290889
    reference_title: "A novel brain-penetrant oral UGT8 inhibitor decreases in vivo galactosphingolipid biosynthesis in murine Krabbe disease."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Administration of RA 5557, reduced pathologically elevated psychosine concentrations (72-86%) in the midbrain and cerebral cortex in twitcher mice"
    explanation: >-
      Quantifies the depletion achieved by the pharmacological arm of the
      discordance, which is the arm that produced no survival benefit.
- discussion_id: gap_krabbe_neuronal_arm_human_relevance
  prompt: >-
    Does cell-autonomous neuronal toxicity contribute materially to disease in
    human Krabbe patients in vivo, or is it a property of converted-cell and
    rodent systems that does not scale to the infantile disease where
    demyelination dominates?
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - pathophysiology#Cell-Autonomous Neuronal Toxicity
  rationale: >-
    The evidence for the neuronal arm is real but narrow in a specific way. The
    human data come from induced neurons converted from the fibroblasts of two
    adult-onset compound heterozygotes, a culture system with no
    oligodendrocytes and no in vivo context, while the functional
    electrophysiology comes from twitcher mouse hippocampus. Human
    neuropathology of Krabbe disease has been reported mainly in terms of white
    matter, globoid cells, and gliosis, and no in vivo rescue experiment has
    isolated the neuronal contribution. Getting this right matters clinically
    rather than only descriptively: if neurons are injured independently of
    myelin, that is a candidate explanation for the residual progression seen
    after hematopoietic stem cell transplantation, and it would argue that
    restoring GALC to the myelinating and phagocytic compartments alone is not
    enough.
  proposed_experiments:
  - experiment_id: exp_krabbe_neuron_specific_galc_restoration
    name: Cell-type-restricted GALC restoration and human neuronal neuropathology
    description: >-
      In twitcher mice, restore GALC conditionally in neurons alone, in
      oligodendrocytes alone, and in the myeloid compartment alone, then compare
      survival, demyelination, and synaptic physiology against global
      restoration. In parallel, apply single-nucleus transcriptomics and
      synaptic and neuritic histopathology to post-mortem infantile and
      late-onset human Krabbe brain, using infant controls, to establish whether
      the neuronal signature seen in culture is present in human tissue.
    experiment_type:
      preferred_term: conditional cell-type-restricted rescue with human post-mortem validation
    decision_criterion: >-
      Neuron-restricted GALC restoration that improves synaptic physiology or
      survival, together with a matching neuronal signature in human tissue,
      would establish the arm as disease-relevant in humans. Absence of a
      neuronal signature in human brain, or no benefit from neuron-restricted
      rescue, would confine the finding to the model systems that generated it.
    would_support:
    - pathophysiology#Cell-Autonomous Neuronal Toxicity
    supporting_outcome:
    - >-
        Neuron-restricted GALC restoration measurably improves synaptic function
        or survival, and human Krabbe brain shows neuritic and synaptic pathology
        beyond what demyelination accounts for.
    refuting_outcome:
    - >-
        Neuron-restricted restoration changes nothing while glial or myeloid
        restoration reproduces the benefit of global restoration, and human tissue
        shows no neuron-intrinsic pathology.
  evidence:
  - reference: PMID:41430252
    reference_title: "Impaired docking and recycling of synaptic vesicles in inherited lysosomal sphingolipidoses."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Collectively, these findings identify presynaptic sphingolipid accumulation and impaired vesicle docking and fusion as shared mechanisms contributing to synaptic failure in several inherited sphingolipidoses, with potential relevance in adult-onset neurodegenerative diseases where lysosomal function is also compromised."
    explanation: >-
      The authors themselves frame the human relevance of the synaptic mechanism
      as potential rather than demonstrated, which is precisely the mismatch
      this discussion records.

📚

References & Deep Research

References

1

PMID:20301416

Krabbe Disease.

No top-level findings curated for this source.

Deep Research

1

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Asta ▸

Asta Literature Retrieval: Pathophysiology and clinical mechanisms of Krabbe Disease. Core disease mechanisms, molecular and cellular pathways,...

Asta Scientific Corpus Retrieval 20 citations 2026-03-30T17:39:06.351751

Asta Literature Retrieval: Pathophysiology and clinical mechanisms of Krabbe Disease. Core disease mechanisms, molecular and cellular pathways,...

This report is retrieval-only and is generated directly from Asta results.

Papers retrieved: 20
Snippets retrieved: 20

Relevant Papers

[1] Fingolimod Rescues Demyelination in a Mouse Model of Krabbe's Disease

Authors: Sibylle Béchet, S. O'Sullivan, J. Yssel, S. Fagan, K. Dev
Year: 2020
Venue: The Journal of Neuroscience
URL: https://www.semanticscholar.org/paper/175e515f4776469b92625a06c1089c12fe11644d
DOI: 10.1523/JNEUROSCI.2346-19.2020
PMID: 32127495
PMCID: 7141882
Citations: 23
Influential citations: 1
Summary: The administration of the therapy known as fingolimod in a mouse model of Krabbe's disease (namely, the twitcher mouse model) significantly rescues myelin levels and regulates the reactivity of glial cells, astrocytes and microglia, in this mouse model.
Evidence snippets:
Snippet 1 (score: 0.500) > Krabbe's disease (KD; globoid cell leukodystrophy) is a devastating illness that is invariably fatal within the first 2 years of life (Graziano and Cardile, 2015). This disease has orphan status affecting ϳ1:100,000 births, although the incidence varies in different populations (Barczykowski et al., 2012). Krabbe's disease is an inherited lipid storage disorder resulting from oligodendrocyte cell death and subsequent loss of myelin. The disease is caused by mutations in the galc gene encoding for galactosylceramidase (galc; Suzuki and Suzuki, 1970). Mutations in galc result in enzymatic dysfunction and a buildup of its two metabolites galactosylceramide and the toxic galactolipid galactosylsphingosine (psychosine; Suzuki, 1998). Aggregations of the latter are particularly apparent in the white matter (WM) of the brain and in sciatic nerves, where it has been shown to inhibit some critical cell processes resulting in oligodendrocyte and Schwann cell apoptosis (Giri et al., 2008;Misslin et al., 2017). Pathological features of Krabbe's disease therefore include profound demyelination and almost complete loss of oligodendrocytes in the white matter, accompanied by inflammatory mechanisms including reactive astrocytosis and infiltration of numerous multinucleated phagocytes termed "globoid cells" (Suzuki, 2003). > The clinical phenotype of Krabbe's disease is classified based on the age of disease onset, with the majority of cases affecting infants (Wenger et al., 2016). Infantile Krabbe's disease typically develops within the first 6 months postnatally with progressive rapid neurologic deterioration. Hallmark symptoms of the classic infantile forms include irritability, hypertonic spasticity, and psy-chomotor stagnation, followed by rapid developmental decline, seizures, and optic atrophy (Graziano and Cardile, 2015). Clinical manifestations thus suggest involvement of both the first and second motor neurons, indicative of a systemic disorder affecting the central as well as the peripheral nervous systems.

[2] Human iPSC-derived astrocytes generated from donors with globoid cell leukodystrophy display phenotypes associated with disease

Authors: Richard Lieberman, Leslie K. Cortes, Grace Gao, Hyejung Park, Bing Wang et al.
Year: 2022
Venue: PLoS ONE
URL: https://www.semanticscholar.org/paper/b5bb977bb3c00e7ca3e3e60ed073d99324ef20a1
DOI: 10.1371/journal.pone.0271360
PMID: 35921286
PMCID: 9348679
Citations: 7
Summary: It is suggested that astrocytes may contribute to the progression of Krabbe disease and warrant further exploration into their role as therapeutic targets.
Evidence snippets:
Snippet 1 (score: 0.464) > Second, the enzyme that synthesizes the neuroinflammatory mediator prostaglandin D2 (HPDGS) is increased in twitcher microglia, and its receptor, prostaglandin DP1, is upregulated in activated twitcher astrocytes. HPDGS inhibition or genetic ablation of the DP1 receptor ameliorated disease phenotypes including astrogliosis, demyelination, and oligodendrocyte apoptosis in the rodent model [37]. Overall, the contribution of astrocytes to the pathology of leukodystrophies is of expanding interest [38], sparked by findings that mutations specifically in astrocyte-expressing glial-fibrillary acidic protein (GFAP) gene cause demyelinating Alexander disease [39], defective support and differentiation of astrocytes results in vanishing white matter disease [40][41][42], and astrocyte dysfunction precedes demyelination observed in X-linked adrenoleukodystrophy [43], among many others [44,45]. Therefore, examination of how Krabbe astrocytes impact neurons and microglia warrant further study, particularly in the setting of human Krabbe patient-derived cells. > iPSCs generated from human fibroblasts [46] offer the ability to differentiate patientderived, disease-relevant cell types. While the murine model of Krabbe disease recapitulates aspects of the human condition [35], and iPSCs have been generated from these mice for differentiation into disease-specific cell types in vitro [47], generation of human-derived cell types relevant to Krabbe disease may provide valuable insight into novel mechanisms related to disease progression. For example, a recent study demonstrated GALC-dependent psychosine accumulation and defective differentiation of human iPSCs into a mixed population of neurons, astrocytes, and oligodendrocyte precursors [48]. Additional studies are needed to elucidate cellular mechanisms implicated in neuropathology, including experiments designed to examine effects of GALC mutations of specific cell types, including astrocytes.

[3] Krabbe disease: psychosine-mediated activation of phospholipase A2 in oligodendrocyte cell death Published, JLR Papers in Press, April 27, 2006.

Authors: Shailendra Giri, Mushfiquddin Khan, R. Rattan, Inderjit Singh, Avtar K. Singh
Year: 2006
Venue: Journal of Lipid Research
URL: https://www.semanticscholar.org/paper/9ac70ad900fac96c3f0af2a7c1771f88bd1f9b81
DOI: 10.1194/jlr.M600084-JLR200
PMID: 16645197
Citations: 117
Influential citations: 9
Summary: It is documents for the first time that psychosine-induced cell death is mediated via the sPLA2 signaling pathway and that inhibitors of sPLA1 may hold a therapeutic potential for protection against oligodendrocyte cell death and resulting demyelination in Krabbe disease.
Evidence snippets:
Snippet 1 (score: 0.451) > of patients with Krabbe disease, leading to the conclusion that progressive accumulation of psychosine is the critical biochemical pathogenetic mechanism of cell death in the Krabbe brain (5,6,10). We have recently reported that psychosine mediates oligodendrocyte cell death via upregulation of reactive oxygen species (ROS)-JNK-AP-1, a pro-apoptotic pathway, and downregulation of the NF-nB pathway, an antiapoptotic pathway (4). However, the mechanism of action of psychosine in the pathophysiology of Krabbe disease is not completely understood. > The observed expression of inflammatory mediators such as TNFa, IL-6, and iNOS in the central nervous systems (CNSs) of Krabbe disease patients and in twitcher mice indicates that the inflammatory response may play a role in the pathobiology of Krabbe disease (7,10). Inflammatory cytokines are known to induce the phospholipase A2 (PLA2) enzyme system. PLA2s hydrolyze phospholipids at the sn-2 position and generate lysolipids and free fatty acids, including arachidonic acid (AA). These mediators are critically involved in the regulation of several physiological events, including cell death (11,12). The PLA2s have been divided into three major groups based on size, ability to be secreted, and calcium dependency (11). The three groups consist of low-molecular-mass sPLA 2 , (13.5-16.8 kDa), calcium-independent phospholipase A 2 (iPLA 2 , 80 kDa), and high-molecular-mass cytosolic phospholipase A 2 (cPLA 2 , 85 kDa) (11). The cPLA 2 , when activated by phosphorylation via an increase in the cytosolic concentration of calcium, translocates from the cytosol to either the nuclear membrane, endoplasmatic reticulum, Golgi, or plasma membrane, depending on cell type and stimulus (12)(13)(14)(15),

[4] Revisiting magnetic resonance imaging pattern of Krabbe disease – Lessons from an Indian cohort

Authors: K. Muthusamy, S. Sudhakar, Maya Thomas, S. Yoganathan, Christhunesa Christudass et al.
Year: 2019
Venue: Journal of Clinical Imaging Science
URL: https://www.semanticscholar.org/paper/265c3bcb602164ee564977c11d0e7323fc5e8168
DOI: 10.25259/JCIS-18-2019
PMID: 31448176
PMCID: 6702867
Citations: 28
Summary: Kabbe disease shows distinct imaging features which correspond to different clinical age-based subtypes, which are reemphasized, highlights a novel imaging appearance in juvenile Krabbe, and also alludes to the rare variant of saposin deficiency.
Evidence snippets:
Snippet 1 (score: 0.429) > Context: Krabbe disease shows considerable heterogeneity in clinical features and disease progression. Imaging phenotypes are equally heterogeneous but show distinct age-based patterns. It is important for radiologists to be familiar with the imaging spectrum to substantially contribute toward early diagnosis, prognostication, and therapeutic decisions. Aims: The study aims to describe different magnetic resonance imaging (MRI) patterns observed in a cohort of children with Krabbe disease and to assess correlation with age-based clinical phenotypes. Materials and Methods: This is a retrospective descriptive study done at the Departments of Radiodiagnosis and Neurological Sciences of our institution, a tertiary care hospital in Southern India. Imaging features of children diagnosed with Krabbe disease over a 10-year period (2009–2018) were collected and analyzed. Results: A total of 38 MRI brain studies from 27 patients were analyzed. Four distinct MRI patterns were recognizable among the different clinical subtypes. All patients from the early and late infantile group showed deep cerebral and cerebellar white matter and dentate hilum involvement. Optic nerve thickening was, however, more common in the former group. Adult-onset subtype showed isolated involvement of corticospinal tract, posterior periventricular white matter, and callosal splenium with the absence of other supra- and infra-tentorial findings. Juvenile subgroup showed heterogeneous mixed pattern with 78% showing adult subtype pattern and 22% showing patchy involvement of deep cerebral white matter with dentate hilum signal changes. Conclusion: Krabbe disease shows distinct imaging features which correspond to different clinical age-based subtypes. This article reemphasizes these distinct imaging phenotypes, highlights a novel imaging appearance in juvenile Krabbe, and also alludes to the rare variant of saposin deficiency. Awareness of these patterns is essential in suggesting the appropriate diagnosis and guiding conclusive diagnostic workup. Large multicenter longitudinal studies are needed to further define the role of imaging in predicting the clinical course and thus to guide therapeutic options.

[5] Changes in Serum Proteomic Profiles at Different Stages of Pregnancy Toxemia in Goats

Authors: M. Uzti̇mür, C. N. Ünal, Gurler Akpinar
Year: 2025
Venue: Journal of Veterinary Internal Medicine
URL: https://www.semanticscholar.org/paper/4b9c488b5dbd65d7b26fd2ad9aed70e8c4b59942
DOI: 10.1111/jvim.70139
PMID: 40492724
PMCID: 12150350
Summary: Understanding the serum proteome profiles of goats with pregnancy toxemia might help identify the proteomes and pathways responsible for the development of this disease and improve diagnosis and treatment.
Evidence snippets:
Snippet 1 (score: 0.427) > The pathophysiology and progression of this disease are not fully understood. > Traditional biomedical research has focused on the analysis of single genes, proteins, metabolites, or metabolic pathways in diseases. This molecular reductionist approach is based on the assumption that identifying genetic variations and molecular components will lead to new treatments for diseases [13][14][15][16]. However, many diseases are complex and multifactorial, and in order to determine the phenotype of such diseases, it is necessary to understand the changes that occur in more than one gene, pathway, protein, or metabolite at the cellular, tissue, and organismal levels [17][18][19]. Therefore, in recent years, proteomics, as one field of multi-omics technologies, has helped in evaluating the complex pathogenetic mechanisms of different diseases from a broad perspective and has made substantial contributions [20,21]. In veterinary medicine, proteomic analysis of metabolic diseases such as ketosis [16], hypocalcemia [22], and fatty liver [23] in dairy cows has contributed valuable insights for the definition of new pathophysiological pathways and new diagnosis and treatment protocols for these diseases. The proteomic approach can contribute importantly to a broad and detailed understanding of the changes that occur at the organismal level associated with the increase in BHBA concentration in goats with pregnancy toxemia. Our aim was to evaluate the serum protein profiles of goats with SPT or CPT using proteomic techniques to determine the proteomic profiles of these animals and to identify the relevant pathophysiological mechanisms.

[6] Organoids in gastrointestinal diseases: from bench to clinic

Authors: Qinying Wang, Fanying Guo, Qinyuan Zhang, Tingting Hu, Yutao Jin et al.
Year: 2024
Venue: MedComm
URL: https://www.semanticscholar.org/paper/9b8880d8b9d45670da950197d7e353794f51d09e
DOI: 10.1002/mco2.574
PMID: 38948115
PMCID: 11214594
Citations: 12
Summary: A comprehensive and systematical depiction of organoids models is drawn, providing a novel insight into the utilization of organoids models from bench to clinic and clinical adhibition.
Evidence snippets:
Snippet 1 (score: 0.412) > Organoids models offer a robust platform for investigating the potential mechanisms of GI diseases and evaluating potential therapeutic interventions.By culturing organoids derived from patients' tissues or stem cells, researchers can delve into disease-specific cellular and molecular pathways, encompassing aberrant cell signaling, perturbed immune responses, and dysfunctional metabolic processes.These disease-specific phenotypes enable the study of disease progression, screening of prospective therapeutics, as well as identification of novel drug targets and mechanisms of action for GI diseases in a clinically relevant context.

[7] Therapies for Mitochondrial Disease: Past, Present, and Future

Authors: Megan Ball, Nicole J. Van Bergen, A. Compton, David R Thorburn, S. Rahman et al.
Year: 2025
Venue: Journal of Inherited Metabolic Disease
URL: https://www.semanticscholar.org/paper/196ee50a950f29bc4134cfb8fe6bdfa9a3a1468b
DOI: 10.1002/jimd.70065
PMID: 40714961
PMCID: 12301291
Citations: 2
Summary: The latest developments in the pursuit to identify effective treatments for mitochondrial disease are examined and the barriers impeding their success in translation to clinical practice are discussed.
Evidence snippets:
Snippet 1 (score: 0.400) > Mitochondrial disease is a diverse group of clinically and genetically complex disorders caused by pathogenic variants in nuclear or mitochondrial DNA‐encoded genes that disrupt mitochondrial energy production or other important mitochondrial pathways. Mitochondrial disease can present with a wide spectrum of clinical features and can often be difficult to recognize. These conditions can be devastating; however, for the majority, there is no targeted treatment. In the last 60 years, mitochondrial medicine has experienced significant evolution, moving from the pre‐molecular era to the Age of Genomics in which considerable gene discovery and advancement in our understanding of the pathophysiology of mitochondrial disease have been made. In the last decade, in response to the urgent need for effective treatments, a wide range of emerging therapies have been developed, driven by innovative approaches addressing both the genetic and cellular mechanisms underpinning the diseases. Emerging therapies include dietary intervention, small molecule therapies aimed to restore mitochondrial function, stem cell or liver transplantation, and gene or RNA‐based therapies. However, despite these advances, translation to clinical practice is complicated by the sheer genetic and clinical complexity of mitochondrial disease, difficulty in efficient and precise delivery of therapies to affected tissues, rarity of individual genetic conditions, lack of reliable biomarkers and clinically relevant outcome measures, and the dearth of natural history data. This review examines the latest developments in the pursuit to identify effective treatments for mitochondrial disease and discusses the barriers impeding their success in translation to clinical practice. While treatment for mitochondrial disease may be on the horizon, many challenges must be addressed before it can become a reality.

[8] Mitochondrial transplantation as a promising therapy for mitochondrial diseases

Authors: Tian-Guang Zhang, Chaoyu Miao
Year: 2022
Venue: Acta Pharmaceutica Sinica. B
URL: https://www.semanticscholar.org/paper/72802097939b0bffc319c93d05128d7e3160e0eb
DOI: 10.1016/j.apsb.2022.10.008
PMID: 36970208
PMCID: 10031255
Citations: 81
Influential citations: 1
Summary: Different techniques used in mitochondrial isolation and delivery, mechanisms of mitochondrial internalization and consequences of mitochondrial transplantation, along with challenges for clinical application are presented.
Evidence snippets:
Snippet 1 (score: 0.399) > Mitochondria, the vital organelles of eukaryotic cells, are integrators of various cellular metabolic pathways, including oxidative phosphorylation, fatty acid oxidation, urea cycle, Krebs cycle, ketogenesis and gluconeogenesis 1 . Mitochondria are also important in many other essential cellular processes such as calcium homeostasis, lipid metabolism, amino acid metabolism, biosynthesis of heme, and thermogenesis 2 . However, they also have important roles in many pathways which can cause both apoptosis and necrosis 3 . Therefore, the importance of the mitochondrion in the maintenance of cellular homeostasis is well established, meanwhile a large amount of evidence shows that mitochondrial dysfunction is deleterious 4 . > Due to the essential function of mitochondria in the human body, mitochondrial dysfunction causes a great variety of mitochondrial diseases, which can affect almost all the organs in the body and present at any age 4,5 . Mitochondrial diseases are a group of metabolic disorders characterized by energy metabolism dysfunction. The pathophysiology is further complicated by the involvement of genetic mutations in nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) which encode mitochondrial proteins. This means that mitochondrial diseases may result from inheritance for nDNA mutations and maternal inheritance for mtDNA mutations. The estimated minimum prevalence of mitochondrial diseases is 1 in 5000, whereas it could be higher 6 . > As advances in molecular and biochemical methodologies led to a better understanding of the mechanisms of mitochondrial disorders for various diseases, mitochondria have become a major target for research institutions and pharma companies. Pharmacological approaches include dietary supplements such as agents increasing respiratory chain function (coenzyme Q10 and riboflavin), agents inducing mitochondrial biogenesis (AICAR and bezafibrate), antioxidants (vitamin C and vitamin E), mitochondrial substrates (L-carnitine) and so on 7,8 . However, these agents fail to significantly alleviate disease symptoms or effectively slow disease progressions, there has therefore been no satisfactory therapeutic strategy available for mitochondrial diseases so far 9 . In addition, all new drugs under clinical trials for treatment of mitochondrial diseases are unable to cure these diseases permanently 9 .

[9] Glial cells in the driver seat of leukodystrophy pathogenesis.

Authors: L. M. Garcia, J. Hacker, Sunetra Sase, L. Adang, Akshata A Almad
Year: 2020
Venue: Neurobiology of disease
URL: https://www.semanticscholar.org/paper/8ce00b0863364b1b2dc5c3c676ba70b914b74660
DOI: 10.1016/j.nbd.2020.105087
PMID: 32977022
Citations: 22
Influential citations: 1
Summary: This review takes a closer look at multiple leukodystrophies, classified based on the primary glial cell type that is affected, and discusses how astrocytes and microglia are affected and impinge on oligodendrocyte, myelin and axonal pathology.
Evidence snippets:
Snippet 1 (score: 0.398) > to demyelination; Treatments for Krabbe include AAV-mediated gene therapy, BMT, ERT, and HSCT to upregulate the expression of GALC enzyme. Psychosine turns on cell death pathways in OPCs and OLs and also activates microglia. The activated J o u r n a l P r e -p r o o f microglia display characteristic morphology of globoid, multinucleated phagocytes and secrete cytokines, ultimately leading to OL toxicity and demyelination; Treatment for Krabbe Disease include AAV-mediated gene therapy, BMT, ERT, and HSCT to upregulate the expression of GALC enzyme; 2. ALSP: Mutation in CSF1R affects microglial proliferation and reduces microglia number affecting OL survival and causing demyelination due to unknown mechanisms; Treatment for ALSP involves elimination or repolarization of tumor-associated macrophages (TAM) with immunomodulatory drugs that inhibit CSF1R; 3. PLOSL: Mutations in the TREM2 and DAP12 genes result in dysfunction of both osteoclasts and microglia. This disrupts the ability of activated microglia turned phagocytes to recognize cellular debris, leading to decreased clearance of myelin and axonal with ongoing myelin loss; Treatments for PLOSL are not yet known; 4. X-ALD: Mutation in ABCD1 gene fails to transport VCLFA in peroxisomes. This build-up of VCLFA leads to oxidative stress and microglia death, which eventually causes OL death and myelin loss; Treatments for X-ALD mostly includes transplantation strategies such as HSCT, HCT, and BMT to prevent progression of the disease phenotype; 5. MLD: > Mutation in the ARSA gene results in accumulation of sulfatides in multiple cell types, including OLs, astrocytes, neurons, Schwann cells, and phagocytes. This sulfatide accumulation activates microglia along with OL toxicity and ultimately leads to demyelination; Treatments for MLD seek to stabilize disease progression through HSCT, UCBT, ERT, BMT, and gene therapy.

[10] Recent advances in modelling of cerebellar ataxia using induced pluripotent stem cells

Authors: M. M. Wong, L. Watson, Esther B. E. Becker
Year: 2017
Venue: Journal of neurology & neuromedicine
URL: https://www.semanticscholar.org/paper/0d962652305116e383ab260b9e82d3a5ffe1722f
DOI: 10.29245/2572.942X/2017/7.1134
PMID: 28825058
PMCID: 5558869
Citations: 9
Summary: This review focuses on recent breakthroughs in generating human iPSC-derived Purkinje cells and highlights the future challenges that will need to be addressed in order to fully exploit these models for the modelling of the molecular mechanisms underlying cerebellar ataxias and the development of effective therapeutics.
Evidence snippets:
Snippet 1 (score: 0.396) > dominant polyglutamine spinocerebellar ataxias (SCAs) are the most studied forms of ataxias. Despite significant clinical and genetic heterogeneity, emerging evidence points to the existence of common pathogenic mechanisms that may be shared by several genetically distinct forms of cerebellar ataxias (reviewed in5-8). However, it is still unclear how the proposed pathological pathways ultimately result in cerebellar dysfunction and degeneration, predominantly affecting Purkinje cells. > Understanding disease mechanisms is key to treating neurodegenerative disorders. The heterogeneous nature of the cerebellar ataxias combined with the unavailability of human brain tissue and the lack of reliable disease models have, however, hampered our understanding of the molecular disease mechanisms underlying cerebellar ataxias and thus, the development of effective therapies. Although mouse models of several cerebellar ataxias, including FRDA and SCAs, have provided valuable insights into the pathophysiology of these disorders (reviewed in9), many questions remain about the observed species differences in disease phenotypes and the effectiveness of potential drugs in clinical trials. > To help translate research from animal models into novel treatments for ataxia patients, it is essential to validate findings in the relevant affected human cell types, particularly in cerebellar Purkinje cells. The current obstacles might be overcome by exploiting recently developed human induced pluripotent stem cell (iPSC) technology and neuronal differentiation protocols.

[11] Neuroimmune mechanisms in Krabbe's disease

Authors: Gregory B Potter, Magdalena A. Petryniak
Year: 2016
Venue: Journal of Neuroscience Research
URL: https://www.semanticscholar.org/paper/201f7962337a320d01bf40c225f3321e3846fafd
DOI: 10.1002/jnr.23804
PMID: 27638616
PMCID: 5129482
Citations: 53
Influential citations: 4
Summary: Mechanistic insight into the inflammatory pathways participating in myelin and axon loss or preservation may lead to novel therapeutic approaches for Krabbe's disease.
Evidence snippets:
Snippet 1 (score: 0.396) > Leukodystrophies are the most common cause of pediatric neurodegeneration, associated with profound childhood morbidity and mortality and resulting in significant emotional and financial burden on families and society (Kohlschutter and Eichler, 2011). Although white matter degeneration is a common feature of these disorders, the activation of the CNS's innate immune response is also observed in most leukodystrophies and coincides with white matter pathology, disease progression, and morbidity (Vitner et al., 2010). Despite this, there is a major gap in our knowledge of the contribution of the immune system to disease phenotype. Krabbe's disease (KD), a leukodystrophy caused by an enzymatic defect in lysosomal galactocerebrosidase (GALC), presents in the most severe infantile form by 6 months of age, followed by death at 2 years of age (Wenger, 1997). This Review refers to neuroinflammation as inflammation characterized by reactivation of resident CNS innate immune cells (microglia) and astrogliosis, which has been previously used to describe aspects of KD pathophysiology (Snook et al., 2014;Hawkins-Salsbury et al., 2015;Lin et al., 2015). It is important to note that there is no clear consensus on the definition or application of the term neuroinflammation with regard to neurodegenerative or lysosomal storage disorders. Some researchers draw a distinction between immune-driven pathology in the brain (i.e., as seen in multiple sclerosis) and innate immune cell activation in the brain (Graeber, 2014), whereas others suggest dividing neuroinflammation between innate immunedriven and adaptive immune-driven neuroinflammation (Heppner et al., 2015). Nevertheless, it is clear that inflammation within the nervous system is a defining characteristic of KD. One of the earliest clinical SIGNIFICANCE Although innate immune activation is a central component of Krabbe's disease that precedes and accelerates with disease progression, the mechanisms by which the immune system contributes to neurodegeneration are still unclear.

[12] “Betwixt Mine Eye and Heart a League Is Took”: The Progress of Induced Pluripotent Stem-Cell-Based Models of Dystrophin-Associated Cardiomyopathy

Authors: D. Rovina, Elisa Castiglioni, Francesco Niro, Sara Mallia, G. Pompilio et al.
Year: 2020
Venue: International Journal of Molecular Sciences
URL: https://www.semanticscholar.org/paper/9303acc2a5c14adba1c342a87f27f2ae2a57195d
DOI: 10.3390/ijms21196997
PMID: 32977524
PMCID: 7582534
Citations: 3
Summary: Cardiovascular cells derived from muscular dystrophy patients’ induced pluripotent stem cells are well suited to mimic dystrophin-associated cardiomyopathy and hold great promise for the development of future fully effective therapies.
Evidence snippets:
Snippet 1 (score: 0.393) > Since inception, iPSC technology has shown enormous potential to model disease, solving many challenges associated with traditional approaches such as animal and primary cell/tissue models. On the basis of their characteristics, patient-specific iPSCs can provide disease-related cells which may have been previously inaccessible, e.g., neurons and cardiomyocytes. Taking advantage of these intrinsic properties, iPSCs carrying patient-specific mutations can be used to model the molecular mechanisms underlying the disease pathophysiology and screen responses to various types of therapeutics. The phenotype ranges that can be investigated by iPSC models involve a broad range of molecular, metabolic, electrophysiological, and cellular analytic techniques. iPSC disease models have been widely applied to study monogenic disorders that are caused by a single gene mutation [130] and sporadic complex disorders involving multiple or unknown genes [131]. The use of iPSC-based models for the latter disease type is more problematic with respect to monogenic diseases, since the phenotype is often the result of multiple small-effect genetic variants in combination with environmental factors. However, this approach was used to model many different complex diseases including Alzheimer's disease, Parkinson's disease, schizophrenia, and cardiac arrhythmias [132][133][134][135]. Without knowing the detailed underlying genetics, differentiated patient-specific iPSCs could provide disease-relevant cells that carry all the genetic elements implicated in the development of the disease and can be useful to analyze the common mechanisms of disease development. Indeed, patient-specific iPSCs obtained from multiple affected individuals that show similar phenotypes could be comparatively investigated in order to find common altered mechanistic pathways or functional activities. > One of the major issues concerning disease modeling using iPSCs is the relative immaturity of the cells differentiated from iPSCs. On the basis of this observation, iPSC-based models are considered more suitable for disorders with an early onset rather than late onset, for which cellular aging could play a role in the disease phenotype. However, despite their fetal phenotype, iPSC-derived cells have highlighted different phenotypes, suggesting that the pathology starts before the appearance of clinical symptoms, potentially allowing the discovery of novel mechanisms involved in the development of pathology [52,136]. > Recently, in

[13] New Insights into Mitochondria in Health and Diseases

Authors: Ya Li, Huhu Zhang, Chunjuan Yu, Xiaolei Dong, Fanghao Yang et al.
Year: 2024
Venue: International Journal of Molecular Sciences
URL: https://www.semanticscholar.org/paper/23002a4ffabfd043f52c664f4d5acab85b8dcac0
DOI: 10.3390/ijms25189975
PMID: 39337461
PMCID: 11432609
Citations: 36
Summary: This overview outlines the various mechanisms by which mitochondria are involved in numerous illnesses and cellular physiological activities and provides new discoveries regarding the involvement of mitochondria in both disorders and the maintenance of good health.
Evidence snippets:
Snippet 1 (score: 0.390) > Mitochondria are essential organelles within cells, playing critical roles not only in energy metabolism but also in various cellular activities, such as cell differentiation, signal transduction, and apoptosis. Mitochondrial dysfunction is implicated in a range of diseases, including but not limited to diabetes and its complications, neurodegenerative disorders, myocardial ischemia-reperfusion injury, and heart failure. Therefore, investigating the structure and function of mitochondria as well as the mechanisms underlying mitochondrial dysfunction in disease contexts holds significant scientific and clinical importance. > Basic scientific research: Diseases manifest systemically and exhibit complexity; thus, it is imperative to understand mitochondrial structure at the molecular level along with known pathways while characterizing novel pathways that influence mitochondrial behavior and functionality. For instance, mapping genetic interactions among genes encoding mitochondrial proteins can elucidate interrelations between different aspects of mitochondrial function. The first focused map of mitochondria has been constructed in yeast models, revealing dense and significant connections among localization pathways distributed across various mitochondrial compartments [126]. > Disease diagnosis: A comprehensive understanding of the mechanisms governing mitochondrial dysfunction can facilitate the development of innovative diagnostic tools. By monitoring specific indicators related to mitochondrial function, earlier diagnosis of diseases associated with mitochondrial impairment becomes feasible. Employing nextgeneration sequencing technologies for analyzing the mitochondrial proteome aids in identifying novel proteins and pathways linked to mitochondria while enabling streamlined diagnostics alongside genetic counseling opportunities for patients with mitochondrial diseases [127]. > Drug development: Advancements in our comprehension of how mitochondria contribute to disease processes may promote targeted therapeutic strategies. For example, metformin-a widely used antidiabetic agent-has recently been repurposed as an anticancer drug; its combination with standard epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) significantly improves progression-free survival rates and overall survival outcomes for patients with advanced lung adenocarcinoma [125]. > Personalized medicine: Given that manifestations of mitochondrial dysfunction may vary among individuals, research into mitochondria provides a theoretical foundation for personalized medicine by allowing tailored treatment plans based on individual states of mitochondrial functionality [127].

[14] New therapeutic targets in rare genetic skeletal diseases

Authors: M. Briggs, Peter A. Bell, M. Wright, K. A. Pirog
Year: 2015
Venue: Expert Opinion on Orphan Drugs
URL: https://www.semanticscholar.org/paper/1363107f71ae6d2d60abca471cddf3da5d13644b
DOI: 10.1517/21678707.2015.1083853
PMID: 26635999
PMCID: 4643203
Citations: 37
Influential citations: 1
Summary: An overview of disease mechanisms that are shared amongst groups of different GSDs and potential therapeutic approaches that are under investigation are described to generate critical mass for the identification and validation of novel therapeutic targets and biomarkers.
Evidence snippets:
Snippet 1 (score: 0.388) > proteins of the cartilage ECM such as type II collagen [50]. However, emerging knowledge suggests that the primary genetic defect may be less important than the cells' response to the expression of the mutant gene product [107]. Moreover, the largely overlooked response of a cell (i.e. chondrocyte) to the abnormal extracellular environment is also important for disease progression as illustrated by several GSDs discussed in this review. > It is important that 'omics'-based approaches and technologies are systematically applied to the study of rare GSDs so that definitive reference profiles and disease signatures are generated for each phenotype. These can then be used in a Systems Biology approach to identify both common and dissimilar pathological signatures and disease mechanisms. This approach is entirely dependent upon relevant in vitro and in vivo models (and also novel 'disease-mechanism phenocopies' [107]) for testing new diagnostic and prognostic tools and for determining the molecular mechanisms that underpin the pathophysiology so that effective therapeutic treatments can be developed and validated. This approach will eventually lead to personalized treatments and care strategies centred on shared disease mechanisms with the use of relevant biomarkers to monitor the efficacy of treatment and disease progression. > It is vital that all relevant stakeholders are involved from the outset in defining the appropriate outcomes of any potential therapeutic regime. The perceptions of a successful therapy can differ widely between the clinical academic community and the relevant patient-support groups and it is vital that there is engagement on all these issues. > In summary, the identification of causative genes and mutations for GSDs over the last 20 years, coupled with the generation and in-depth analysis of a plethora of relevant cell and mouse models, has derived new knowledge on disease mechanisms and suggested potential therapeutic targets. The fast-evolving hypothesis that clinically disparate diseases can share common disease mechanisms is a powerful concept that will generate critical mass for the identification and validation of novel therapeutic targets and biomarkers.

[15] Protein kinases in neurodegenerative diseases: current understandings and implications for drug discovery

Authors: Xiao-lei Wu, Zhang-zhong Yang, Jinjun Zou, Huile Gao, Zhenhua Shao et al.
Year: 2025
Venue: Signal Transduction and Targeted Therapy
URL: https://www.semanticscholar.org/paper/57c532f807605e5181ca30a675ad0d79e3625453
DOI: 10.1038/s41392-025-02179-x
PMID: 40328798
PMCID: 12056177
Citations: 32
Influential citations: 1
Summary: The role and complexity of kinase–kinase networks in the pathogenesis of neurodegenerative diseases are discussed, and the advances of clinical applications of protein kinase inhibitors or novel kinase-targeted therapeutic strategies for effective prevention and early intervention are illustrated.
Evidence snippets:
Snippet 1 (score: 0.387) > Neurodegenerative diseases (e.g., Alzheimer’s, Parkinson’s, Huntington’s disease, and Amyotrophic Lateral Sclerosis) are major health threats for the aging population and their prevalences continue to rise with the increasing of life expectancy. Although progress has been made, there is still a lack of effective cures to date, and an in-depth understanding of the molecular and cellular mechanisms of these neurodegenerative diseases is imperative for drug development. Protein phosphorylation, regulated by protein kinases and protein phosphatases, participates in most cellular events, whereas aberrant phosphorylation manifests as a main cause of diseases. As evidenced by pharmacological and pathological studies, protein kinases are proven to be promising therapeutic targets for various diseases, such as cancers, central nervous system disorders, and cardiovascular diseases. The mechanisms of protein phosphatases in pathophysiology have been extensively reviewed, but a systematic summary of the role of protein kinases in the nervous system is lacking. Here, we focus on the involvement of protein kinases in neurodegenerative diseases, by summarizing the current knowledge on the major kinases and related regulatory signal transduction pathways implicated in diseases. We further discuss the role and complexity of kinase–kinase networks in the pathogenesis of neurodegenerative diseases, illustrate the advances of clinical applications of protein kinase inhibitors or novel kinase-targeted therapeutic strategies (such as antisense oligonucleotides and gene therapy) for effective prevention and early intervention.

[16] 18O-assisted dynamic metabolomics for individualized diagnostics and treatment of human diseases

Authors: E. Nemutlu, Song Zhang, N. Juranic, A. Terzic, S. Macura et al.
Year: 2012
Venue: Croatian Medical Journal
URL: https://www.semanticscholar.org/paper/880f053c7f060db4b990e447d0a22c4b69372ddb
DOI: 10.3325/cmj.2012.53.529
PMID: 23275318
PMCID: 3541579
Citations: 28
Summary: The potential use of dynamic phosphometabolomic platform for disease diagnostics currently under development at Mayo Clinic is described and discussed briefly.
Evidence snippets:
Snippet 1 (score: 0.387) > Living cells represent an integrated and interacting network of genes, transcripts, proteins, small signaling molecules, and metabolites that define cellular phenotype and function. Traditionally the focus of biomedical research was on individual genes, single protein targets, single metabolites, and metabolic or signaling pathways. This "molecular reductionist" paradigm was based on the assumption that identifying genetic variations and molecular components would lead to discovery of cures for human diseases. However, most of diseases are complex and multi-factorial and the disease phenotype is determined by the alterations of multiple genes, pathways, proteins and metabolites (at cellular, tissue, and organismal levels). Therefore, an integrated "omics" approach is more viable direction for uncovering alterations in metabolic networks, disease mechanisms, and mechanisms of drug effects. > Recent advent of large-scale metabolomics and fluxomic (metabolite dynamics and metabolic flux analysis) completed the "omics revolution" (Figure 1), where genomics, transcriptomics, proteomics, metabolomics, and fluxomics all together complement phenotype determination of living organism. Such integrated "omics" cascades provide a framework for advances in system and network biology, integrative physiology, and system medicine as well as system pharmacology and regenerative medicine. Noteworthy is the "reverse omic" approach or "metabolomicsinformed pharmacogenomics, " where discovery of specific metabolite changes have led to discovery of genetic alterations (2). Therefore, bringing new "omics" technologies to clinical practice will improve disease diagnostics and treatment by targeting drugs and procedures for each unique transcriptomic and metabolomic profiles.

[17] Modeling psychiatric disorders: from genomic findings to cellular phenotypes

Authors: Anna Falk, Vivi M. Heine, A. Harwood, Patrick F. Sullivan, M. Peitz et al.
Year: 2016
Venue: Molecular Psychiatry
URL: https://www.semanticscholar.org/paper/235b41240d78140de7ab06a3ad8a7d0b1bdff1a5
DOI: 10.1038/mp.2016.89
PMID: 27240529
PMCID: 4995546
Citations: 77
Influential citations: 2
Summary: The challenges for modeling of psychiatric disorders, potential solutions and how iPSC technology can be used to develop an analytical framework for the evaluation and therapeutic manipulation of fundamental disease processes are critically reviewed.
Evidence snippets:
Snippet 1 (score: 0.386) > The key challenge for iPSC-based disease modeling is to identify one or more relevant cellular phenotypes that accurately represent the disease pathophysiology. Increasing numbers of reports have demonstrated that for many diseases specific pathophysiology can be captured in human iPSC-based disease models. These range from cardiovascular disease, 44,45 cancer, 46,47 ocular disease, 48,49 diabetes mellitus 50,51 and neurological disorders of the brain. 52,53 Can the same approach be applied to complex psychiatric disorders? > The problem is that almost all psychiatric disorders are characterized by clinical signs and symptoms, but lack independent verification from objective biomarkers. Thus, how might these clinical phenotypes manifest themselves in terms of cell behavior? The identity of robust cellular 'readouts', which typify any psychiatric disorder, is a crucial unsolved problem and an area of intense study 54 (Table 2). When satisfactorily answered, this will herald a new degree of biological objectivity and quantification for the study of psychiatric disorders. > The aim is to find a single or small number of cell phenotypes or parameters that strongly associate with psychiatric disorders, and establish a cellular profile characteristic of cells derived from the general patient population. Although a consensus set of cellular phenotypes for psychiatric disorder is yet to be established, we can define some of their desired characteristics. First, cellular phenotypes have to relate to the biological pathways identified by genetics. Second, although there are many risk genes in disparate biological pathways, at some level, phenotypes should converge onto a much smaller grouping. Third, phenotypes need to be quantifiable. Finally, to be useful for drug development cellular phenotypes should be reversed by pharmacological treatment, although not necessarily by drugs in current use. > Although human iPSC-based approaches underrepresent the complexity of the human central nervous system, cellular phenotypes are likely to lie more proximal to molecular disease mechanisms than phenotypes seen at the level of a tissue or organism, 55 and thus may bypass compensatory homeostatic (2) Gene expression profiles of SCZ human iPSC neurons identified altered expression of many components of the cyclic AMP and WNT signaling pathways. > (3

[18] Novel Approaches to Studying SLC13A5 Disease

Authors: Adriana S. Beltran
Year: 2024
Venue: Metabolites
URL: https://www.semanticscholar.org/paper/8469c534cd81d96f84b61e2d963dead12088feb7
DOI: 10.3390/metabo14020084
PMID: 38392976
PMCID: 10890222
Citations: 2
Summary: Current technologies for generating patient-specific induced pluripotent stem cells (iPSCs) and their inherent advantages and limitations are discussed, followed by a summary of the methods for differentiating iPSCs into neurons, hepatocytes, and organoids.
Evidence snippets:
Snippet 1 (score: 0.385) > The precise pathophysiology underlying how SLC13A5 loss-of-function results in epilepsy refractory to treatment is a subject of open and ongoing research. Several hypotheses suggest SLC13A5 alters metabolic pathways, leading to neuronal dysfunction. Conversely, therapeutic inhibition of NaCT in the liver is a target to improve metabolic diseases, including non-alcoholic fatty liver disease, obesity, and insulin resistance. Thus, functionally accurate modeling and characterization of the mechanisms involved in citrate transport disruption are critical for understanding its role in human disease. > IPSC-derived cellular systems are a powerful tool for modeling rare human genetic diseases, such as SLC13A5 (Figure 5). IPSCs derived from patients containing the genetic information of the disease can overcome the limitations of animal models, providing access to relevant human cell types that recapitulate the disease phenotype. For instance, patient-derived iPSCs differentiated into neurons or hepatocytes can be used to investigate molecular and cellular mechanisms, including citrate transport and accumulation, energy metabolism, oxidative stress, and other cellular processes. They can also be used to define the spectrum of the disease and how different mutations might lead to various disease severities, screen for potential therapeutic compounds that can restore the transporter function or ameliorate the symptoms, and enable personalized medicine approaches that can tailor treatments to individual patients based on their genetic background and disease severity. > transport disruption are critical for understanding its role in human disease. > IPSC-derived cellular systems are a powerful tool for modeling rare human genetic diseases, such as SLC13A5 (Figure 5). IPSCs derived from patients containing the genetic information of the disease can overcome the limitations of animal models, providing access to relevant human cell types that recapitulate the disease phenotype. For instance, patient-derived iPSCs differentiated into neurons or hepatocytes can be used to investigate molecular and cellular mechanisms, including citrate transport and accumulation, energy metabolism, oxidative stress, and other cellular processes.

[19] Computational drug discovery approaches identify mebendazole as a candidate treatment for autosomal dominant polycystic kidney disease

Authors: P. Brownjohn, A. Zoufir, Daniel J O’Donovan, Saatviga Sudhahar, A. Syme et al.
Year: 2024
Venue: Frontiers in Pharmacology
URL: https://www.semanticscholar.org/paper/a595e78572ca02b8cb2897bfc4a989a2b021b279
DOI: 10.3389/fphar.2024.1397864
PMID: 38846086
PMCID: 11154008
Citations: 2
Summary: It is determined that the anthelmintic mebendazole was a potent anti-cystic agent in human cellular and in vivo models of ADPKD, and is likely acting through the inhibition of microtubule polymerisation and protein kinase activity.
Evidence snippets:
Snippet 1 (score: 0.384) > Targets and molecules were ultimately filtered for validation based on biological and chemical insights, and the potential for clinical translation.Earlier this year, Wilk et al., 2023 applied a similar transcriptomic approach to us, in that case making use of publicly available transcriptomic datasets to create Pkd2-specific ADPKD disease signatures, from which signature reversion was sought from the Library of Integrated Network-based Cellular Signatures (LINCs) drug signature database in order to identify drug repurposing candidates.While one group has previously made use of a knowledge graph-based approach to prioritise preclinically active compounds with the highest chance of clinical translation (Malas et al., 2019), to our knowledge, the current study provides the first combined application of transcriptomic and machine-learning approaches to identify and prioritise putative treatments for ADPKD, and further deconvolute potential mechanisms of action for experimental validation. > In summary we report, using computational, in vitro and in vivo approaches, that the anthelmintic drug mebendazole ameliorates disease-relevant phenotypes in cellular and animal models of ADPKD.We further show that this effect is likely primarily due to the inhibitory effect of mebendazole on the polymerisation of microtubules, which underlie cellular processes important in ADPKD, including cell proliferation, transport, and cilia signalling, and extends previous work linking the importance of the microtubule network to ADPKD pathophysiology.We also describe the inhibitory profile of mebendazole on known and novel protein kinase targets, some of which have previously been implicated in ADPKD, suggesting mebendazole may be acting via polypharmacology to impact disease mechanisms.We acknowledge that further experimental efforts will be required to confirm the actions of mebendazole on these putative targets in relevant disease model systems.It would be particularly informative to investigate these mechanisms in dedicated in vivo studies, where the effects of mebendazole on a wider range of ADPKD-relevant cell types and phenotypes could be evaluated.

[20] Chemotherapy and Mechanisms of Resistance in Breast Cancer

Authors: A. Oliveira, R. E. Santos, F. F. O. Rodrigues
Year: 2012
Venue: Unknown venue
URL: https://www.semanticscholar.org/paper/502a86d8bcd7208be6f539fcceba631f82f25a7d
DOI: 10.5772/24629
Summary: The addition of adjuvant polychemotherapy in advanced breast cancer showed gain by controlling survival of micrometastases in patients with lymph nodes affected by cancer or not.
Evidence snippets:
Snippet 1 (score: 0.384) > The main reasons responsible for treatment failure in cancer patients are the mechanisms of drug resistance and emergence of disseminated disease (Terek et al, 2003). We identified two types of resistance most relevant to BC: primary resistance, which corresponds to the clinical situation where the patient showed no response to therapy, and secondary or acquired resistance in which, initially, there is an observed response and a subsequent failure of the treatment regimen (Kroger et al, 1999). Several mechanisms may cause the phenotype of multidrug resistance to chemotherapy drugs and are well characterized in in vitro experiments, including alterations in systemic pharmacology (pharmacokinetics and metabolism), extracellular mechanisms (tumor environment, multicellular drug resistance), and cellular mechanisms (cellular pharmacology, activation and inactivation of drugs, modification of specific targets and regulatory pathways of apoptosis) (Leonessa et al, 2003, Riddick et al, 2005. Identification of factors that affect cell metabolism, which are related to drug resistance, will enable the identification of which patients are at particular risk of treatment failure. Among the biochemical and molecular mechanisms of drug resistance, we stress: changes in the activity of topoisomerase II, alterations in the DNA repair mechanism, overexpression of P-glycoprotein; high intracellular concentrations of enzymes purification of cellular metabolism -among them enzymes the family of glutathione S-transferases (GSTs) and changes in the mechanisms of signaling via c-Jun N-terminal kinase 1 (JNK1) -and "apoptosis signal-regulating kinase (ASK1) required for activation of the" mitogenactivated protein (MAP kinases) in apoptosis and cellular restoration. These pathways are also mediated by proteins encoded by genes of GSTs (O'Brien, Tew, 1996;Burg, Mulder, 2002, L'Ecuyer et al, 2004). Different response rates to particular chemotherapy regimens, as observed in patient groups with the same biological characteristics and stage, suggest the existence of different mechanisms of drug resistance, probably induced by genetic alterations (Hayes, Pulford, 1995;O'Brien , Tew, 1996;Pakunlu et al, 2003). Among the mechanisms of purification of cellular metabolism involved in the

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Asta Literature Retrieval: Pathophysiology and clinical mechanisms of Krabbe Disease. Core disease mechanisms, molecular and cellular pathways,...

Relevant Papers

[1] Fingolimod Rescues Demyelination in a Mouse Model of Krabbe's Disease

[2] Human iPSC-derived astrocytes generated from donors with globoid cell leukodystrophy display phenotypes associated with disease

[3] Krabbe disease: psychosine-mediated activation of phospholipase A2 in oligodendrocyte cell death Published, JLR Papers in Press, April 27, 2006.

[4] Revisiting magnetic resonance imaging pattern of Krabbe disease – Lessons from an Indian cohort

[5] Changes in Serum Proteomic Profiles at Different Stages of Pregnancy Toxemia in Goats

[6] Organoids in gastrointestinal diseases: from bench to clinic

[7] Therapies for Mitochondrial Disease: Past, Present, and Future

[8] Mitochondrial transplantation as a promising therapy for mitochondrial diseases

[9] Glial cells in the driver seat of leukodystrophy pathogenesis.

[10] Recent advances in modelling of cerebellar ataxia using induced pluripotent stem cells

[11] Neuroimmune mechanisms in Krabbe's disease

[12] “Betwixt Mine Eye and Heart a League Is Took”: The Progress of Induced Pluripotent Stem-Cell-Based Models of Dystrophin-Associated Cardiomyopathy

[13] New Insights into Mitochondria in Health and Diseases

[14] New therapeutic targets in rare genetic skeletal diseases

[15] Protein kinases in neurodegenerative diseases: current understandings and implications for drug discovery

[16] 18O-assisted dynamic metabolomics for individualized diagnostics and treatment of human diseases

[17] Modeling psychiatric disorders: from genomic findings to cellular phenotypes

[18] Novel Approaches to Studying SLC13A5 Disease

[19] Computational drug discovery approaches identify mebendazole as a candidate treatment for autosomal dominant polycystic kidney disease

[20] Chemotherapy and Mechanisms of Resistance in Breast Cancer

Notes