BCKDK Deficiency

Mendelian MONDO:0013970 Pathograph 28 Show in embeddings browser Inborn Error of Metabolism Inborn Disorder of Branched-Chain Amino Acid Metabolism

Branched-chain keto acid dehydrogenase kinase (BCKDK) deficiency is a rare, autosomal recessive, potentially treatable neurometabolic disorder of branched-chain amino acid (BCAA) metabolism. BCKDK is the mitochondrial kinase that phosphorylates and inactivates the E1-alpha subunit of the branched-chain ketoacid dehydrogenase (BCKDH) complex, the rate-limiting, flux-generating step of BCAA catabolism. Biallelic loss-of-function variants in BCKDK remove this inhibitory brake, leaving BCKDH constitutively active and driving excessive catabolism of leucine, isoleucine, and valine. The result is markedly reduced plasma and cerebrospinal fluid BCAA concentrations and a neurodevelopmental phenotype of autism spectrum disorder, intellectual disability/developmental delay, epilepsy/epileptic encephalopathy, and (often progressive postnatal) microcephaly. Motor and language impairment, regression, movement disorder, feeding difficulty, and sensorineural hearing loss broaden the recognized spectrum. Unlike classic maple syrup urine disease, which features toxic BCAA accumulation from deficient BCKDH activity, recessive BCKDK loss produces BCAA depletion. Dietitian-directed high-protein intake and BCAA supplementation are the principal disease-directed interventions in reported human cohorts, especially when started early, although mouse studies show that simply raising systemic BCAAs may not correct aberrant catabolic flux or brain delivery.

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1
Definitions
1
Inheritance
6
Pathophys.
15
Phenotypes
3
Gaps
28
Pathograph
1
Genes
3
Variants
3
Medical Actions
4
Differentials
1
Datasets
2
Trials
5
Models
10
References
1
Deep Research
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Classifications

Harrison's Part
GENETICS ENVIRONMENT DISEASE
ICIMD (Inherited Metabolic Disorders)
branched chain amino acids
📘

Definitions

1
Recessive BCKDK loss-of-function deficiency
A treatable autosomal recessive aminoacidopathy in which biallelic loss-of-function BCKDK variants remove inhibitory phosphorylation of BCKDH, causing excessive BCAA oxidation, low plasma and CSF BCAAs, and a neurodevelopmental disorder.
OTHER
Show evidence (1 reference)
PMID:35216372 SUPPORT Human Clinical
"Hyperactivity of BCKDH and over-consumption of BCAA were demonstrated by functional tests in cells transfected with the mutant BCKDK."
Defines the loss-of-inhibition biochemical mechanism.
👪

Inheritance

1
Autosomal recessive inheritance HP:0000007
Disease-causing BCKDK deficiency results from biallelic loss-of-function variants. This is distinct from the proposed heterozygous gain-of-function BCKDK biochemical phenotype with elevated BCAAs.
Autosomal recessive inheritance
Show evidence (1 reference)
PMID:22956686 SUPPORT Human Clinical
"We focused on the identification of homozygous variants predicted to result in loss of protein function, consistent with the presumed mode of recessive inheritance."
Directly supports recessive inheritance for BCKDK loss-of-function disease.
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Discussions and Knowledge Gaps

3
Does population newborn screening followed by presymptomatic dietary treatment prevent autism, epilepsy, and developmental disability?
KNOWLEDGE GAP OPEN gap_bckdk_newborn_screening_and_early_treatment
Attached to
diagnosis#Candidate newborn dried-blood-spot screening treatments#BCAA-enriched high-protein dietary supplementation
Retrospective dried-blood-spot values support biochemical detectability, and three children treated before age two had favorable autism outcomes, but the cohort is small and uncontrolled. Prospective screening performance, cutoffs, false-positive burden, and neurodevelopmental efficacy remain unestablished.
Show evidence (2 references)
PMID:36729635 SUPPORT Human Clinical
"Among cases with follow-up data, none of the three patients starting treatment before 2 years of age developed autism at follow-up."
Suggests an early-treatment benefit but is based on only three nonrandomized cases.
PMID:36729635 SUPPORT Human Clinical
"NBS in DBS identified BCAA levels significantly lower than those of the normal population."
Supports newborn biochemical detectability without establishing program-level screening performance.
Why do reported human cohorts improve with BCAA-rich dietary treatment while enteral supplementation worsens neurodevelopmental deficits in one mouse model?
HUMAN MODEL MISMATCH OPEN mismatch_human_and_mouse_bcaa_supplementation
Attached to
treatments#BCAA-enriched high-protein dietary supplementation pathophysiology#Aberrant catabolic flux beyond simple BCAA insufficiency
Human evidence comes from uncontrolled observational cohorts receiving a combined high-protein and BCAA regimen, whereas the mouse experiment tests a defined model and enteral supplementation. Species, developmental timing, dosing, diet composition, brain delivery, and residual genotype effects may explain the divergence.
Show evidence (2 references)
PMID:36729635 SUPPORT Human Clinical
"After treatment with a high-protein diet (≥ 2 g/kg/day) and BCAA supplementation (100-250 mg/kg/day), plasma BCAA increased significantly (P < 0.001), motor functions and head circumference stabilized/improved in 13/13 and in 11/15 patients, respectively."
Summarizes the reported human biochemical and clinical response.
PMID:38770403 SUPPORT Model Organism
"BCAA supplementation exacerbated neurodevelopmental deficits and did not correct biochemical abnormalities despite increasing systemic BCAA levels."
Establishes the opposite outcome in the mouse intervention experiment.
Which mechanism most directly drives human neurodevelopmental disease: systemic depletion, impaired BCAA-derived nitrogen delivery, brain nutrient-stress signaling, or abnormal downstream catabolic flux?
KNOWLEDGE GAP OPEN gap_brain_delivery_and_catabolic_flux
Attached to
pathophysiology#Reduced BCAA-derived nitrogen delivery and brain nutrient-stress response pathophysiology#Aberrant catabolic flux beyond simple BCAA insufficiency
New mouse results bridge systemic depletion to brain metabolism, while genetic rescue indicates that excess pathway flux matters independently of the measured BCAA concentration. Human tissue-level evidence remains absent, and patient-derived neurons did not reproduce a major cell-autonomous phenotype.
Show evidence (2 references)
PMID:41587643 SUPPORT Model Organism
"Thus, in the non-growing adult constitutive BCKDH activation limits BCAA-derived nitrogen delivery to brain and alters AA transporters as part of an adaptive ISR during nutrient scarcity."
Demonstrates impaired BCAA-derived nitrogen delivery in vivo.
PMID:38770403 SUPPORT Model Organism
"These data suggest that aberrant flux through the BCAA catabolic pathway, not just BCAA insufficiency, may contribute to disease pathology."
Establishes the competing or complementary catabolic-flux mechanism.
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Pathophysiology

6
BCKDK loss of function
Biallelic loss-of-function variants in BCKDK (frameshift, nonsense, missense, or in-frame deletion) reduce or abolish the mitochondrial branched-chain ketoacid dehydrogenase kinase. Patient cells show reduced BCKDK mRNA (consistent with nonsense-mediated decay), undetectable BCKDK protein, and loss of the phospho-E1-alpha (Ser293) signal that normally inactivates BCKDH.
BCKDK hgnc:16902 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves BCKDK (hgnc:16902). hgnc:16902 is a gene from the HUGO Gene Nomenclature Committee.
branched-chain ketoacid dehydrogenase kinase activity GO:0047323 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased branched-chain ketoacid dehydrogenase kinase activity, annotated with [3-methyl-2-oxobutanoate dehydrogenase (acetyl-transferring)] kinase activity (GO:0047323). GO:0047323 is a molecular function from the Gene Ontology. ↓ DECREASED
mitochondrion GO:0005739 Gene Ontology (GO) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in mitochondrion (GO:0005739). GO:0005739 is an anatomical location from the Gene Ontology.
Downstream
Constitutive BCKDH activation and excessive BCAA catabolism Loss of BCKDK-mediated inhibitory phosphorylation of the BCKDH E1-alpha subunit leaves the BCKDH complex constitutively active, increasing catabolic flux through the rate-limiting step of BCAA degradation.
Show evidence (2 references)
PMID:22956686 SUPPORT Human Clinical
"We have identified inactivating mutations in the gene BCKDK (Branched Chain Ketoacid Dehydrogenase Kinase) in consanguineous families with autism, epilepsy, and intellectual disability."
Directly identifies inactivating BCKDK mutations as the cause of the disorder.
PMID:22956686 SUPPORT Human Clinical
"Patients with homozygous BCKDK mutations display reductions in BCKDK messenger RNA and protein, E1α phosphorylation, and plasma branched-chain amino acids."
Confirms loss of BCKDK mRNA, protein, and E1-alpha phosphorylation in patients with homozygous mutations.
Constitutive BCKDH activation and excessive BCAA catabolism
The branched-chain ketoacid dehydrogenase (BCKDH) complex catalyzes the irreversible, rate-limiting step in BCAA catabolism. Without BCKDK-mediated phosphorylation, BCKDH activity is unchecked, accelerating the breakdown of leucine, isoleucine, and valine.
branched-chain amino acid catabolic process GO:0009083 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased branched-chain amino acid catabolic process (GO:0009083). GO:0009083 is a biological process from the Gene Ontology. ↑ INCREASED protein dephosphorylation of BCKDH E1-alpha GO:0006470 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased protein dephosphorylation of BCKDH E1-alpha, annotated with protein dephosphorylation (GO:0006470). GO:0006470 is a biological process from the Gene Ontology. ↑ INCREASED
mitochondrion GO:0005739 Gene Ontology (GO) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in mitochondrion (GO:0005739). GO:0005739 is an anatomical location from the Gene Ontology.
Experimental models
Mutant BCKDK transfection functional assay CELL LINE The assay measures loss of BCKDK-mediated restraint on BCKDH.
Downstream
Systemic and CSF BCAA depletion Accelerated BCKDH-mediated catabolism depletes circulating and central branched-chain amino acids. BCAAs are essential amino acids that cannot be synthesized de novo, so increased catabolism is not compensated by synthesis.
Aberrant catabolic flux beyond simple BCAA insufficiency Beyond depleting circulating and central BCAAs, the constitutively active BCKDH complex drives aberrant flux through the BCAA catabolic pathway itself. Mouse-model evidence indicates that this excess catabolic flux (not just the resulting low BCAA levels) is a mechanistic contributor to disease.
Show evidence (2 references)
PMID:35216372 SUPPORT In Vitro
"Hyperactivity of BCKDH and over-consumption of BCAA were demonstrated by functional tests in cells transfected with the mutant BCKDK."
Functional cell assays directly demonstrate BCKDH hyperactivity and BCAA over-consumption from mutant BCKDK.
PMID:27472223 SUPPORT Model Organism
"when Ser293 is not phosphorylated, BCKDH activity is unchecked and the levels of the BCAAs will decrease dramatically."
Rat model establishes that loss of Ser293 phosphorylation leaves BCKDH unchecked, dramatically lowering BCAAs.
Systemic and CSF BCAA depletion
Markedly reduced concentrations of leucine, isoleucine, and valine in plasma and cerebrospinal fluid are the biochemical hallmark of BCKDK deficiency. Because BCAAs share blood-brain barrier transporters (notably LAT1, SLC7A5/SLC3A2) with other large neutral amino acids, low plasma BCAAs also perturb brain concentrations of other large neutral amino acids that are precursors for neurotransmitters.
branched-chain amino acid catabolic process GO:0009083 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased branched-chain amino acid catabolic process (GO:0009083). GO:0009083 is a biological process from the Gene Ontology. ↑ INCREASED amino acid transmembrane transport across the blood-brain barrier GO:0003333 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves dysregulated amino acid transmembrane transport across the blood-brain barrier, annotated with amino acid transmembrane transport (GO:0003333). GO:0003333 is a biological process from the Gene Ontology. ↕ DYSREGULATED
Downstream
Reduced BCAA-derived nitrogen delivery and brain nutrient-stress response Low systemic BCAAs restrict the BCAA-derived nitrogen reaching the brain and alter amino-acid-transporter and integrated-stress-response programs, especially under nutrient scarcity.
Hypovalinemia Systemic BCAA depletion includes low plasma valine.
Hypoleucinemia Systemic BCAA depletion includes low plasma leucine.
Hypoisoleucinemia Systemic BCAA depletion includes low plasma isoleucine.
Decreased CSF valine concentration Central BCAA depletion includes decreased CSF valine concentration.
Show evidence (2 references)
PMID:22956686 SUPPORT Human Clinical
"We measured plasma BCAAs in our patients and found that each patient with a homozygous mutation showed notably lower levels of plasma BCAAs than their healthy relatives and with respect to reference ranges"
Directly documents lower plasma BCAAs in patients with homozygous BCKDK mutations.
PMID:22956686 SUPPORT Model Organism
"Because several of these amino acids are precursors for important neurotransmitters, it remains a possibility that the reduced BCAAs and/or the increased LNAAs contribute to the neurological phenotype."
Mouse brain amino acid profiling links blood-brain barrier transport imbalance and neurotransmitter precursor disturbance to the neurological phenotype.
Reduced BCAA-derived nitrogen delivery and brain nutrient-stress response
Constitutive peripheral BCAA oxidation limits the circulating precursor pool and reduces incorporation of BCAA-derived nitrogen into brain glutamate. During fasting, Bckdk-null brain activates the integrated stress response, increases Atf4 targets including Slc7a5, and reduces protein synthesis, whereas skeletal muscle is comparatively resilient. This supplies a mechanistic bridge between systemic amino-acid depletion and neurologic vulnerability but does not yet explain every human developmental feature.
neuron CL:0000540 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neuron (CL:0000540). CL:0000540 is a cell type from the Cell Ontology.
Downstream
Neurodevelopmental and epileptic phenotype Chronic disruption of brain precursor delivery and stress adaptation contributes to motor and neurologic disease, while the full developmental causal chain remains incompletely resolved.
Show evidence (2 references)
PMID:41587643 SUPPORT Model Organism
"In contrast, Bckdk KO brains exhibited ISR activation during fasting, and up-regulation of Atf4 and its target genes, including Slc7a5 mRNA."
Demonstrates a brain-selective nutrient-stress response in the knockout model.
PMID:41587643 SUPPORT Model Organism
"This creates a vulnerability in brain not observed in skeletal muscle."
Supports tissue-selective brain vulnerability.
Neurodevelopmental and epileptic phenotype
The disorder localizes chiefly to the central nervous system, with neurons strongly implicated. In mouse studies, cortex-neuron involvement is central to the neurological abnormalities, and the spontaneous frogleg rat model affects both the central and peripheral nervous systems.
neuron CL:0000540 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neuron (CL:0000540). CL:0000540 is a cell type from the Cell Ontology.
protein phosphorylation (loss of E1-alpha phosphorylation) GO:0006468 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased protein phosphorylation (loss of E1-alpha phosphorylation), annotated with protein phosphorylation (GO:0006468). GO:0006468 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
Autistic behavior Neurodevelopmental involvement manifests clinically as autistic behavior.
Intellectual disability Neurodevelopmental involvement manifests clinically as intellectual disability.
Global developmental delay Neurodevelopmental involvement manifests clinically as global developmental delay.
Epileptic encephalopathy Neuronal dysfunction manifests as epileptic encephalopathy in severe reported cases.
Seizures Neuronal dysfunction manifests as epileptic seizures.
Microcephaly The neurodevelopmental phenotype includes postnatal or progressive microcephaly.
Motor delay Neurodevelopmental involvement commonly impairs gross motor function.
Language impairment Language development is prominently affected.
Developmental regression Some affected children lose previously acquired skills.
Sensorineural hearing impairment Sensorineural hearing loss is an uncommon but documented feature.
Feeding difficulties Feeding difficulty occurs in a minority of reported patients.
Show evidence (2 references)
PMID:22956686 SUPPORT Model Organism
"Adults developed neurological abnormalities, such as tremors, epileptic seizures, and hindlimb clasping phenotypes observed in some other mouse models of autism spectrum disorders"
Bckdk knockout mice recapitulate the neurological/epileptic phenotype, supporting CNS neuronal involvement.
PMID:27472223 SUPPORT Model Organism
"The frogleg phenotype shares important characteristics with a previously described Bckdk knockout mouse and with human subjects with Bckdk mutations."
Rat model demonstrates a nervous-system phenotype shared with the mouse model and human patients.
Aberrant catabolic flux beyond simple BCAA insufficiency
Recent mouse-model evidence challenges a purely "BCAA-insufficiency" model. In a Bckdk-deficient mouse, enteral BCAA supplementation raised systemic BCAA levels but exacerbated neurodevelopmental deficits and failed to correct biochemical abnormalities, suggesting that aberrant flux through the BCAA catabolic pathway (not just low BCAAs) contributes to disease. Genetic re-regulation of catabolism via Dbt haploinsufficiency partially rescued biochemical and behavioral phenotypes.
branched-chain amino acid catabolic process GO:0009083 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased branched-chain amino acid catabolic process (GO:0009083). GO:0009083 is a biological process from the Gene Ontology. ↑ INCREASED
Downstream
Neurodevelopmental and epileptic phenotype Excess pathway flux contributes to behavioral disease independently of the measured systemic BCAA concentration.
Show evidence (2 references)
PMID:38770403 SUPPORT Model Organism
"These data suggest that aberrant flux through the BCAA catabolic pathway, not just BCAA insufficiency, may contribute to disease pathology."
Mouse-model data support aberrant catabolic flux as a mechanistic contributor beyond BCAA insufficiency.
PMID:38770403 SUPPORT Model Organism
"genetic re-regulation of BCAA catabolism, through Dbt haploinsufficiency, partially rescued biochemical and behavioral phenotypes in BCKDK deficient mice."
Genetic re-regulation of downstream BCAA catabolism via Dbt haploinsufficiency partially rescued biochemical and behavioral phenotypes, supporting aberrant catabolic flux (rather than simple BCAA insufficiency) as the disease mechanism and identifying substrate-reduction-style re-regulation as a candidate therapy.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for BCKDK Deficiency Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

15
Digestive 1
Feeding difficulties OCCASIONAL HP:0011968 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Feeding difficulties (HP:0011968). HP:0011968 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:36729635 SUPPORT Human Clinical
"3/21 had sensorineural hearing loss and 4/20 feeding difficulties."
Documents feeding difficulties in four evaluated cohort members.
Ear 1
Sensorineural hearing impairment OCCASIONAL HP:0000407 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Sensorineural hearing impairment (HP:0000407). HP:0000407 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:36729635 SUPPORT Human Clinical
"3/21 had sensorineural hearing loss and 4/20 feeding difficulties."
Documents sensorineural hearing loss in three cohort members.
Head and Neck 1
Microcephaly HP:0000252 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Microcephaly (HP:0000252). HP:0000252 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:35216372 SUPPORT Human Clinical
"In three siblings with severe developmental delays, microcephaly, autism spectrum disorder and epileptic encephalopathy, we identified a new homozygous in-frame deletion (c.999_1001delCAC; p.Thr334del) of BCKDK."
Microcephaly is directly documented in the affected siblings.
Nervous System 6
Autistic behavior HP:0000729 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Autistic behavior (HP:0000729). HP:0000729 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:22956686 SUPPORT Human Clinical
"We have identified inactivating mutations in the gene BCKDK (Branched Chain Ketoacid Dehydrogenase Kinase) in consanguineous families with autism, epilepsy, and intellectual disability."
Autism was a defining feature in the consanguineous families with BCKDK mutations.
Intellectual disability HP:0001249 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Intellectual disability (HP:0001249). HP:0001249 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:22956686 SUPPORT Human Clinical
"Thus, autism presenting with intellectual disability and epilepsy caused by BCKDK mutations represents a potentially treatable syndrome."
Intellectual disability is identified as a core component of the BCKDK-mutation syndrome.
Global developmental delay HP:0001263 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Global developmental delay (HP:0001263). HP:0001263 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:35216372 SUPPORT Human Clinical
"In three siblings with severe developmental delays, microcephaly, autism spectrum disorder and epileptic encephalopathy, we identified a new homozygous in-frame deletion (c.999_1001delCAC; p.Thr334del) of BCKDK."
Directly documents severe developmental delays in the affected siblings.
Seizures HP:0001250 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Seizure (HP:0001250). HP:0001250 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:22956686 SUPPORT Human Clinical
"two siblings with autism, intellectual disability (ID), and either seizure or abnormal electroencephalogram (EEG)"
Directly documents seizures (or abnormal EEG) in affected siblings.
Motor delay VERY_FREQUENT HP:0001270 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Motor delay (HP:0001270). HP:0001270 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:36729635 SUPPORT Human Clinical
"18/21 had gross motor function (GMF) impairment with GMF III or worse in 5/18"
Quantifies motor impairment in the largest reported cohort.
Developmental regression OCCASIONAL HP:0002376 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Developmental regression (HP:0002376). HP:0002376 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:36729635 SUPPORT Human Clinical
"Regression was reported in six patients."
Directly documents regression in six of 21 cohort members.
Other 6
Epileptic encephalopathy HP:0200134 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Epileptic encephalopathy (HP:0200134). HP:0200134 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:35216372 SUPPORT Human Clinical
"In three siblings with severe developmental delays, microcephaly, autism spectrum disorder and epileptic encephalopathy, we identified a new homozygous in-frame deletion (c.999_1001delCAC; p.Thr334del) of BCKDK."
Epileptic encephalopathy is directly documented in the affected siblings.
Language impairment VERY_FREQUENT HP:0002463 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Language impairment (HP:0002463). HP:0002463 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:36729635 SUPPORT Human Clinical
"16/16 intellectual disability, 17/17 language impairment, 12/17 autism spectrum disorder, 9/21 epilepsy"
Documents language impairment in every evaluated cohort member.
Hypovalinemia HP:0500132 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypovalinemia (HP:0500132). HP:0500132 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:22956686 SUPPORT Human Clinical
"each patient with a homozygous mutation showed notably lower levels of plasma BCAAs than their healthy relatives and with respect to reference ranges"
Documents reduced plasma BCAAs (including valine) in affected patients.
Hypoleucinemia HP:0500143 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypoleucinemia (HP:0500143). HP:0500143 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:22956686 SUPPORT Human Clinical
"each patient with a homozygous mutation showed notably lower levels of plasma BCAAs than their healthy relatives and with respect to reference ranges"
Documents reduced plasma BCAAs (including leucine) in affected patients.
Hypoisoleucinemia HP:0500144 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypoisoleucinemia (HP:0500144). HP:0500144 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:22956686 SUPPORT Human Clinical
"each patient with a homozygous mutation showed notably lower levels of plasma BCAAs than their healthy relatives and with respect to reference ranges"
Documents reduced plasma BCAAs (including isoleucine) in affected patients.
Decreased CSF valine concentration HP:0500188 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Decreased CSF valine concentration (HP:0500188). HP:0500188 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:35216372 SUPPORT Human Clinical
"Plasma and cerebrospinal fluid concentrations of BCAA were markedly reduced."
Directly documents markedly reduced CSF BCAA, including valine, in affected patients.
🧬

Genetic Associations

1
BCKDK pathogenic variants
Gene: BCKDK hgnc:16902 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is BCKDK (hgnc:16902). hgnc:16902 is a gene from the HUGO Gene Nomenclature Committee.
Autosomal recessive
Show evidence (1 reference)
PMID:22956686 SUPPORT Human Clinical
"In each of these families, we identified a distinct, null, homozygous mutation in the gene Branched Chain Ketoacid Dehydrogenase Kinase (BCKDK)."
Confirms BCKDK as the causal gene with distinct homozygous null mutations across families.
Variants (3)
p.Arg156* and p.M74fs (null variants)
The original report identified a nonsense variant (C466T; premature stop at position 156, p.Arg156*) in family 558 and a single-base deletion (c.G222del) causing a frameshift terminating the protein at position 74 (p.M74fs) in family 18. Both are null, homozygous, loss-of-function variants segregating recessively.
Show evidence (1 reference)
PMID:22956686 SUPPORT Human Clinical
"In family 558, we identified a cytosine-to-thymine substitution in exon 4 (C466T) resulting in a premature stop codon at amino acid position 156, prior to the kinase domain"
Directly identifies the p.Arg156* null variant in family 558.
p.Arg224Pro (missense)
A missense variant (c.G671C) substituting a highly conserved arginine with proline at position 224 was identified in a third family; structural modeling predicted disruption of the kinase domain. Missense variants caused less severe plasma BCAA reductions than null variants.
Show evidence (1 reference)
PMID:22956686 SUPPORT Human Clinical
"leading to the substitution of a highly conserved arginine with a proline at position 224 in BCKDK"
Directly identifies the p.Arg224Pro missense variant.
c.999_1001delCAC (p.Thr334del)
A homozygous in-frame deletion (c.999_1001delCAC; p.Thr334del) was identified in three siblings; functional tests in transfected cells demonstrated BCKDH hyperactivity and BCAA over-consumption.
Show evidence (1 reference)
PMID:35216372 SUPPORT Human Clinical
"we identified a new homozygous in-frame deletion (c.999_1001delCAC; p.Thr334del) of BCKDK."
Directly identifies the homozygous p.Thr334del in-frame deletion.
🗃️

External Assertions

1
ClinGen BCKDK-deficiency gene-disease validity assertion
ClinGen Gene-Disease Validity gene disease validity assertion_f90aaad0-b56a-41dc-8d1f-9d12fc66113f-2019-01-18T170000.000Z
The pinned ClinGen snapshot records a Definitive autosomal recessive BCKDK–branched-chain keto acid dehydrogenase kinase deficiency assertion from the Aminoacidopathy Gene Curation Expert Panel.
Show evidence (1 reference)
PMID:36729635 SUPPORT Human Clinical
"Branched-chain ketoacid dehydrogenase kinase (BCKDK) deficiency causes branched-chain amino acid (BCAA) depletion and is linked to a neurodevelopmental disorder characterized by autism, intellectual disability and microcephaly."
Independently supports the exact gene-disease relationship represented by the ClinGen assertion.
💊

Medical Actions

3
BCAA-enriched high-protein dietary supplementation
Action: amino acid supplementationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is amino acid supplementation, annotated with Nutritional Supplementation (NCIT:C15425). NCIT:C15425 is a clinical intervention from the NCI Thesaurus. Ontology label: Nutritional Supplementation NCIT:C15425
Agent: leucine CHEBI:25017 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses leucine (CHEBI:25017). CHEBI:25017 is a therapeutic agent from Chemical Entities of Biological Interest. isoleucine CHEBI:24898 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses isoleucine (CHEBI:24898). CHEBI:24898 is a therapeutic agent from Chemical Entities of Biological Interest. valine CHEBI:27266 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses valine (CHEBI:27266). CHEBI:27266 is a therapeutic agent from Chemical Entities of Biological Interest.
The principal reported disease-directed intervention is a dietitian-directed high-protein diet plus oral leucine, isoleucine, and valine. In the largest human cohort, reported intake was at least 2 g protein/kg/day with total BCAA supplementation of 100–250 mg/kg/day; plasma BCAAs rose and motor function and head growth commonly stabilized or improved. Earlier reports found strong seizure control with less complete developmental response. These uncontrolled human observations should be interpreted separately from a 2024 mouse study in which enteral BCAAs raised systemic concentrations but worsened neurodevelopmental deficits and failed to correct the modeled pathway abnormality.
Mechanism Target:
MODULATES Systemic and CSF BCAA depletion — BCAA supplementation replenishes depleted branched-chain amino acids, restoring plasma concentrations and improving seizure control.
Show evidence (1 reference)
PMID:35216372 SUPPORT Human Clinical
"Treatment with pharmacological doses of BCAA allowed the restoring of BCAA concentrations and greatly improved seizure control."
BCAA supplementation restored BCAA concentrations and improved seizure control in patients.
Target Phenotypes: Motor delay HP:0001270 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Motor delay (HP:0001270). HP:0001270 is a phenotype from the Human Phenotype Ontology. Microcephaly HP:0000252 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Microcephaly (HP:0000252). HP:0000252 is a phenotype from the Human Phenotype Ontology. Seizure HP:0001250 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Seizure (HP:0001250). HP:0001250 is a phenotype from the Human Phenotype Ontology. Language impairment HP:0002463 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Language impairment (HP:0002463). HP:0002463 is a phenotype from the Human Phenotype Ontology.
Show evidence (5 references)
PMID:35216372 SUPPORT Human Clinical
"Behavioral and developmental skills of the patients improved to a lesser extent."
Documents the more modest behavioral/developmental response compared with seizure control.
PMID:22956686 SUPPORT Human Clinical
"by supplementing the diet of human cases with BCAAs, we have been able to normalize their plasma BCAA levels"
Dietary BCAA supplementation normalized plasma BCAA levels in human cases.
PMID:36729635 SUPPORT Human Clinical
"After treatment with a high-protein diet (≥ 2 g/kg/day) and BCAA supplementation (100-250 mg/kg/day), plasma BCAA increased significantly (P < 0.001), motor functions and head circumference stabilized/improved in 13/13 and in 11/15 patients, respectively."
Provides cohort-level dosing and biochemical, motor, and head-growth outcomes.
+ 2 more references
Metabolic and developmental surveillance
Category: Monitoring Action: clinical monitoringNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is clinical monitoring, annotated with Clinical Evaluation (NCIT:C124351). NCIT:C124351 is a clinical intervention from the NCI Thesaurus. Ontology label: Clinical Evaluation NCIT:C124351
Follow quantitative plasma BCAAs together with growth and head circumference, motor and language development, seizure control, feeding, and hearing. These are rational response and safety domains from the available cohort—not evidence for a validated visit interval—and dietary changes should be individualized by a metabolic team and dietitian.
Show evidence (2 references)
PMID:36729635 SUPPORT Human Clinical
"After treatment with a high-protein diet (≥ 2 g/kg/day) and BCAA supplementation (100-250 mg/kg/day), plasma BCAA increased significantly (P < 0.001), motor functions and head circumference stabilized/improved in 13/13 and in 11/15 patients, respectively."
Identifies plasma BCAAs, motor function, and head growth as observed treatment-response domains.
PMID:36729635 SUPPORT Human Clinical
"3/21 had sensorineural hearing loss and 4/20 feeding difficulties."
Supports inclusion of hearing and feeding in individualized clinical follow-up.
Genetic counseling
Action: Genetic CounselingNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Genetic Counseling (NCIT:C15240). NCIT:C15240 is a clinical intervention from the NCI Thesaurus. NCIT:C15240
Given autosomal recessive inheritance, genetic counseling and recurrence-risk assessment are indicated for carrier parents, with carrier and cascade testing for at-risk relatives.
Show evidence (1 reference)
PMID:22956686 SUPPORT Human Clinical
"We focused on the identification of homozygous variants predicted to result in loss of protein function, consistent with the presumed mode of recessive inheritance."
Establishes recessive inheritance, which underlies the role of genetic counseling and recurrence-risk assessment.
🔬

Biochemical Markers

1
Plasma branched-chain amino acids (DECREASED)
Context: Low plasma leucine, isoleucine, and valine are the diagnostic biochemical hallmark of BCKDK deficiency. There is no abnormal urinary BCAA excretion or organic acid accumulation, distinguishing it from defects that cause BCAA overflow. A retrospective review showed that low BCAA values are also detectable on newborn dried blood spots, suggesting amenability to newborn screening if low (rather than high) BCAA values are actively flagged.
Pathograph Readouts
Readout Of Systemic and CSF BCAA depletion Negative Diagnostic
Low plasma BCAA reports the increased BCKDH-mediated catabolic flux resulting from loss of BCKDK inhibitory phosphorylation.
Show evidence (1 reference)
PMID:35216372 SUPPORT Human Clinical
"Plasma and cerebrospinal fluid concentrations of BCAA were markedly reduced."
Reduced plasma/CSF BCAA is the biochemical readout of the underlying catabolic block reversal.
Show evidence (1 reference)
PMID:35216372 SUPPORT Human Clinical
"a retrospective review of the newborn screening results allowed the identification of a strong decrease in BCAA concentrations on dried blood spots, suggesting that BCKDK is a new treatable metabolic disorder probably amenable to newborn screening programs."
Confirms low BCAA on newborn dried blood spots and proposes newborn-screening amenability.
🔬

Diagnosis

4
Quantitative plasma amino acid analysis
In a child with otherwise unexplained developmental delay, autism, epilepsy, or postnatal microcephaly, quantify plasma leucine, isoleucine, and valine. Concordant depression of all three BCAAs is the principal biochemical clue.
clinical laboratory procedure NCIT:C25294 NCI Thesaurus (NCIT)
Markers: Plasma leucine, isoleucine, and valine
Results: BCAAs below age-appropriate reference ranges support BCKDK deficiency.
Show evidence (1 reference)
PMID:36729635 SUPPORT Human Clinical
"At diagnosis, BCAA levels (leucine, valine and isoleucine) were below reference values in plasma and in CSF."
Establishes the low-BCAA biochemical signature at diagnosis.
Cerebrospinal-fluid amino acid analysis
CSF amino acid analysis can demonstrate central BCAA depletion when lumbar puncture is clinically indicated, but it is not required solely to diagnose the disorder when plasma biochemistry and molecular testing are conclusive.
clinical laboratory procedure NCIT:C25294 NCI Thesaurus (NCIT)
Markers: CSF leucine, isoleucine, and valine
Results: Low CSF BCAAs support central amino-acid depletion.
Show evidence (1 reference)
PMID:35216372 SUPPORT Human Clinical
"Plasma and cerebrospinal fluid concentrations of BCAA were markedly reduced."
Directly supports the CSF biochemical finding.
Molecular confirmation of biallelic BCKDK variants
Sequence BCKDK through a neurodevelopmental or metabolic gene panel, exome, or genome and assess copy-number variation as appropriate. Biallelic pathogenic loss-of-function variants confirm the recessive deficiency in a compatible biochemical and clinical context.
molecular genetic testing NCIT:C19770 NCI Thesaurus (NCIT)
Results: Biallelic pathogenic BCKDK variants establish the molecular diagnosis.
Show evidence (1 reference)
PMID:40851941 SUPPORT Human Clinical
"Therefore, genetic testing was done, and genetic variants compatible with BCKDK deficiency were detected."
Four additional children were diagnosed after low BCAAs prompted molecular testing.
Candidate newborn dried-blood-spot screening
Retrospective newborn dried-blood-spot analysis can identify unusually low BCAAs before symptoms. This supports candidacy for newborn screening but does not by itself establish a universal screening standard or validated cutoffs.
clinical laboratory procedure NCIT:C25294 NCI Thesaurus (NCIT)
Markers: Dried-blood-spot leucine, isoleucine, and valine
Results: BCAA values significantly below the newborn reference population warrant confirmatory testing.
Show evidence (1 reference)
PMID:36729635 SUPPORT Human Clinical
"NBS in DBS identified BCAA levels significantly lower than those of the normal population."
Demonstrates retrospective detection of the low-BCAA signature in newborn specimens.
📈

Progression

3
Birth and presymptomatic interval
Age: Newborn period through infancy
Congenital microcephaly is not typical in the largest cohort. Low BCAAs can already be detected retrospectively in newborn dried blood spots, creating an opportunity for diagnosis before the neurodevelopmental phenotype is established.
Show evidence (2 references)
PMID:36729635 SUPPORT Human Clinical
"No microcephaly was observed at birth, but 17/20 developed microcephaly during follow-up."
Establishes the predominantly postnatal evolution of microcephaly.
PMID:36729635 SUPPORT Human Clinical
"NBS in DBS identified BCAA levels significantly lower than those of the normal population."
Shows that the biochemical signature can precede clinical diagnosis.
Untreated neurodevelopmental disease
Age: Infancy through childhood
Developmental and language impairment, autism, motor dysfunction, epilepsy, postnatal microcephaly, and occasional regression accumulate over childhood. The cohort was diagnosed from 8 months to 16 years, demonstrating a wide diagnostic delay.
Show evidence (2 references)
PMID:36729635 SUPPORT Human Clinical
"Patients were diagnosed between 8 months and 16 years (mean: 5.8 years, 43% female)."
Defines the observed diagnostic age range.
PMID:36729635 SUPPORT Human Clinical
"Regression was reported in six patients."
Documents that loss of previously acquired function can occur.
Diet-treated follow-up
Age: After biochemical and molecular diagnosis
Plasma BCAAs generally rise with high-protein intake and BCAA supplementation. Motor function, head growth, seizures, speech, and psychomotor development may stabilize or improve, with the most favorable reports after early treatment. Existing cohorts are small and uncontrolled, so treatment cannot be assumed to reverse established disability.
Show evidence (2 references)
PMID:36729635 SUPPORT Human Clinical
"motor functions and head circumference stabilized/improved in 13/13 and in 11/15 patients, respectively."
Quantifies motor and head-growth outcomes in treated patients with follow-up data.
PMID:40851941 SUPPORT Human Clinical
"By initiating a BCAAs-rich regimen, the patients had significant improvements in psychomotor and speech development."
Adds 2025 case-series evidence for developmental improvement after dietary therapy.
🔀

Differential Diagnoses

4

Conditions with similar clinical presentations that must be differentiated from BCKDK Deficiency:

Maple syrup urine disease MONDO:0009563
Overlapping Features Classic BCKD-complex deficiency produces the biochemical opposite of recessive BCKDK deficiency: BCAAs accumulate rather than fall, and alloisoleucine is the pathognomonic biochemical discriminator.
Distinguishing Features
  • Elevated BCAAs and alloisoleucine in maple syrup urine disease
  • Low plasma and CSF BCAAs in recessive BCKDK deficiency
Show evidence (1 reference)
PMID:38736638 SUPPORT Human Clinical
"Biochemical evidence for MSUD includes elevated branched-chain amino acids (BCAA) and the pathognomonic presence of alloisoleucine."
Directly states the biochemical pattern that distinguishes MSUD from BCKDK deficiency.
Heterozygous BCKDK gain-of-function biochemical phenotype
Overlapping Features A proposed heterozygous p.Thr372Arg gain-of-function allele produces autosomal dominant elevation of BCAAs and alloisoleucine with a mild or asymptomatic MSUD-like course. It is a distinct allelic condition and must not be merged with biallelic loss-of-function BCKDK deficiency.
Distinguishing Features
  • Heterozygous rather than biallelic BCKDK variation
  • Elevated rather than depleted BCAAs
  • Detectable alloisoleucine and often benign clinical course
Show evidence (1 reference)
PMID:38736638 SUPPORT Human Clinical
"The BCKDK variant modeling indicated a gain-of-function which leads to impaired BCAA catabolism consistent with the biochemical evidence in this cohort."
Supports the mechanistically opposite gain-of-function allelic phenotype.
Other genetic neurodevelopmental disorders
Overlapping Features Autism, developmental delay, epilepsy, and microcephaly are nonspecific. Concordant low plasma BCAAs followed by biallelic BCKDK findings separates this treatable aminoacidopathy from phenotypically overlapping genetic neurodevelopmental disorders.
Distinguishing Features
  • Low leucine, isoleucine, and valine
  • Biallelic pathogenic BCKDK variants
Show evidence (1 reference)
PMID:40851941 SUPPORT Human Clinical
"Neuroimaging assessments revealed negligible findings; thus, metabolic tests were sent, in which BCAAs were lower than normal limits."
Shows how metabolic testing distinguished BCKDK deficiency in children with nonspecific NDD and autism.
Dietary protein insufficiency
Overlapping Features Inadequate protein intake can lower circulating essential amino acids, but the discovery cohort did not have protein-deficient diets and retained normal fasting concentrations of other essential amino acids.
Distinguishing Features
  • Dietary history and broader essential-amino-acid pattern
  • Persistent selective BCAA depletion despite adequate protein intake
  • Biallelic pathogenic BCKDK variants
Show evidence (1 reference)
PMID:22956686 SUPPORT Human Clinical
"None of the affected individuals was known to eat a diet deficient in protein, as evidenced by their normal fasting plasma levels of the other essential amino acids"
Excludes simple dietary protein deficiency in the original affected families.
📊

Related Datasets

1
Bckdk-knockout and wild-type adult mouse skeletal-muscle RNA sequencing geo:GSE309126
Bulk RNA-seq comparing freely fed Bckdk-knockout and wild-type non-growing adult male mouse skeletal muscle. The study found few transcriptomic differences and should not be interpreted as a human brain-disease dataset.
BULK RNA SEQ
PMID:41587643
Organism: Mus musculus. GEO. The publication's data-availability statement identifies accession GSE309126; analyzed tissue was skeletal muscle.
Show evidence (1 reference)
PMID:41587643 SUPPORT Model Organism
"RNA sequencing data produced in this study are available in the Gene Expression Ominbus database: accession numberGSE309126."
The publication directly identifies the deposited RNA-seq accession.
🔬

Clinical Trials

2
NCT05687474 — Baby Detect genomic newborn screening NOT_APPLICABLE COMPLETED
Completed observational newborn-screening program in the Wallonia-Brussels Federation using targeted sequencing from neonatal dried blood spots. BCKDK deficiency is included among the program's treatable early-onset conditions; this is a screening implementation study, not a therapeutic efficacy trial.
Show evidence (1 reference)
clinicaltrials:NCT05687474 SUPPORT Other
"Baby Detect Project is an innovative NBS program using a panel of target sequencing that aims to identify 126 treatable severe early onset genetic diseases at birth caused by 361 genes."
Establishes the design and treatable-disease scope of the genomic newborn-screening program.
NCT01238250 — Simons Searchlight NOT_APPLICABLE RECRUITING
Recruiting international observational registry collecting longitudinal medical, behavioral, learning, and developmental information from people with rare neurodevelopmental genetic variants. BCKDK is listed among the eligible genetic conditions; the study is not an interventional BCKDK trial.
Show evidence (1 reference)
clinicaltrials:NCT01238250 SUPPORT Other
"Simons Searchlight is an observational, online, international research program for families with rare genetic variants that cause neurodevelopmental disorders and may be associated with autism."
Establishes the registry's observational design and relevant neurodevelopmental scope.
🧫

Experimental Models

2
Patient-derived BCKDK-deficient iPSC neural progenitors and neurons IPSC_DERIVED_MODEL
Patient and control cells were compared across reduced extracellular BCAA concentrations. The cultured neural cells showed no major genotype-dependent survival, proliferation, morphologic, transcriptional, or metabolic phenotype, defining an important negative result and favoring a non-cell-autonomous systemic mechanism.
Organism
human NCBITaxon:9606 NCBI Taxonomy (NCBITaxon) Relation: this experimental model is built in this organism This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
Cell source
Fibroblast-derived iPSCs from two affected sisters and an unaffected brother, differentiated through neural progenitor cells into mature neurons
Findings
Cultured BCKDK-deficient neurons did not show a major cell-autonomous phenotype.
"There were no appreciable differences in gene expression or metabolic profiles of these cultured neurons, arguing against a major cell-autonomous role for BCKDK in the pathogenesis of the disease."
Show evidence (1 reference)
PMID:22956686 SUPPORT In Vitro
"There were no appreciable differences in gene expression or metabolic profiles of these cultured neurons, arguing against a major cell-autonomous role for BCKDK in the pathogenesis of the disease."
The patient-derived neural model yielded a negative cell-autonomous result.
Show evidence (1 reference)
PMID:22956686 SUPPORT In Vitro
"To uncover cellular phenotypes of human cells lacking BCKDK, we generated pluripotent stem cells (iPSCs) from the fibroblasts of the healthy brother and the two affected sisters from family 558 by means of episomal reprogramming"
Defines the provenance and genotype contrast of the patient-derived model.
Mutant BCKDK transfection functional assay CELL_LINE
Expression of mutant BCKDK was used to test its functional effect on BCKDH activity and BCAA consumption.
Organism
human NCBITaxon:9606 NCBI Taxonomy (NCBITaxon) Relation: this experimental model is built in this organism This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
Cell source
Cells transfected with the human BCKDK p.Thr334del allele
Pathograph links
Constitutive BCKDH activation and excessive BCAA catabolism The assay measures loss of BCKDK-mediated restraint on BCKDH.
Show evidence (1 reference)
PMID:35216372 SUPPORT In Vitro
"Hyperactivity of BCKDH and over-consumption of BCAA were demonstrated by functional tests in cells transfected with the mutant BCKDK."
Direct functional evidence that the allele increases BCKDH activity and BCAA consumption.
Findings
The p.Thr334del allele caused BCKDH hyperactivity and BCAA over-consumption.
"Hyperactivity of BCKDH and over-consumption of BCAA were demonstrated by functional tests in cells transfected with the mutant BCKDK."
Show evidence (1 reference)
PMID:35216372 SUPPORT In Vitro
"Hyperactivity of BCKDH and over-consumption of BCAA were demonstrated by functional tests in cells transfected with the mutant BCKDK."
Directly supports the functional finding.
Show evidence (1 reference)
PMID:35216372 SUPPORT In Vitro
"Hyperactivity of BCKDH and over-consumption of BCAA were demonstrated by functional tests in cells transfected with the mutant BCKDK."
Defines the assay and its mechanistic result.
🐁

Animal Models

3
Bckdk knockout (Bckdk−/−) Mouse (Mus musculus) Knockout
Constitutive Bckdk-null mice reproduce the biochemical depletion and a reversible neurologic phenotype. Recent isotope-tracing work adds impaired BCAA-derived nitrogen delivery to brain and nutrient-stress-dependent motor dysfunction, while also showing relative skeletal-muscle resilience.
Reduced circulating and brain BCAAs Growth retardation Tremor, seizures, and hindlimb clasping Impaired motor coordination during protein restriction
Species
Mouse (Mus musculus)
Genotype
Bckdk knockout (Bckdk−/−)
Show evidence (2 references)
PMID:22956686 SUPPORT Model Organism
"Adults developed neurological abnormalities, such as tremors, epileptic seizures, and hindlimb clasping phenotypes observed in some other mouse models of autism spectrum disorders"
Documents the core neurologic phenotype of the knockout mouse.
PMID:41587643 SUPPORT Model Organism
"Bckdk KO showed normal grip strength but poor beam traversal and reduced wheel running during protein restriction."
Establishes coordination and activity deficits under nutrient stress.
Homozygous spontaneous Bckdk p.Gly369Glu frogleg allele Rat (Rattus norvegicus) Missense loss-of-function model
The autosomal recessive frogleg rat carries a damaging kinase-domain Bckdk missense allele, loses BCKDH Ser293 phosphorylation, and develops central and peripheral nervous-system abnormalities with marked BCAA depletion.
Hindlimb splaying and neuromuscular dysfunction Reduced brain weight and ventricular dilation Seizures Reduced circulating BCAAs
Species
Rat (Rattus norvegicus)
Genotype
Homozygous spontaneous Bckdk p.Gly369Glu frogleg allele
Show evidence (2 references)
PMID:27472223 SUPPORT Model Organism
"circulating levels of the BCAAs are reduced by 70-80% in animals homozygous for the mutation."
Directly quantifies the model's systemic biochemical lesion.
PMID:27472223 SUPPORT Model Organism
"The frogleg phenotype shares important characteristics with a previously described Bckdk knockout mouse and with human subjects with Bckdk mutations."
Supports translational correspondence across rat, mouse, and human disease.
Bckdk deficiency with Dbt haploinsufficiency Mouse (Mus musculus) Genetic rescue model
Reducing dosage of the downstream BCKDH E2 component Dbt partially re-regulates excessive BCAA catabolism in Bckdk-deficient mice. The result supports catabolic-flux suppression as a preclinical strategy rather than establishing a human treatment.
Partial biochemical rescue Partial behavioral rescue
Species
Mouse (Mus musculus)
Genotype
Bckdk deficiency with Dbt haploinsufficiency
Show evidence (1 reference)
PMID:38770403 SUPPORT Model Organism
"genetic re-regulation of BCAA catabolism, through Dbt haploinsufficiency, partially rescued biochemical and behavioral phenotypes in BCKDK deficient mice."
Directly demonstrates partial genetic rescue of biochemical and behavioral phenotypes.
{ }

Source YAML

click to show 
name: BCKDK Deficiency
creation_date: "2026-06-04T12:00:00Z"
category: Mendelian
synonyms:
- Branched-chain keto acid dehydrogenase kinase deficiency
- BCKD-kinase deficiency
- BCKDKD
- Autism-epilepsy syndrome due to branched chain ketoacid dehydrogenase kinase deficiency
description: >-
  Branched-chain keto acid dehydrogenase kinase (BCKDK) deficiency is a rare,
  autosomal recessive, potentially treatable neurometabolic disorder of
  branched-chain amino acid (BCAA) metabolism. BCKDK is the mitochondrial kinase
  that phosphorylates and inactivates the E1-alpha subunit of the branched-chain
  ketoacid dehydrogenase (BCKDH) complex, the rate-limiting, flux-generating step
  of BCAA catabolism. Biallelic loss-of-function variants in BCKDK remove this
  inhibitory brake, leaving BCKDH constitutively active and driving excessive
  catabolism of leucine, isoleucine, and valine. The result is markedly reduced
  plasma and cerebrospinal fluid BCAA concentrations and a neurodevelopmental
  phenotype of autism spectrum disorder, intellectual disability/developmental
  delay, epilepsy/epileptic encephalopathy, and (often progressive postnatal)
  microcephaly. Motor and language impairment, regression, movement disorder,
  feeding difficulty, and sensorineural hearing loss broaden the recognized
  spectrum. Unlike classic maple syrup urine disease, which features toxic BCAA
  accumulation from deficient BCKDH activity, recessive BCKDK loss produces BCAA
  depletion. Dietitian-directed high-protein intake and BCAA supplementation are
  the principal disease-directed interventions in reported human cohorts,
  especially when started early, although mouse studies show that simply raising
  systemic BCAAs may not correct aberrant catabolic flux or brain delivery.
disease_term:
  preferred_term: BCKDK deficiency
  term:
    id: MONDO:0013970
    label: branched-chain keto acid dehydrogenase kinase deficiency
parents:
- Inborn Error of Metabolism
- Inborn Disorder of Branched-Chain Amino Acid Metabolism
classifications:
  harrisons_chapter:
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
    evidence:
    - reference: PMID:36729635
      reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Twenty-one patients with BCKDK mutations were included from 13 families."
      explanation: Supports classification as a Mendelian genetic disease.
  icimd_category:
  - classification_value: branched_chain_amino_acids
    evidence:
    - reference: PMID:35216372
      reference_title: Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Plasma and cerebrospinal fluid concentrations of BCAA were markedly
        reduced.
      explanation: The defining biochemical lesion is depletion of essential branched-chain amino acids.
external_assertions:
- name: ClinGen BCKDK-deficiency gene-disease validity assertion
  source: ClinGen Gene-Disease Validity
  assertion_type: gene_disease_validity
  external_id: assertion_f90aaad0-b56a-41dc-8d1f-9d12fc66113f-2019-01-18T170000.000Z
  url: https://search.clinicalgenome.org/kb/gene-validity/CGGV:assertion_f90aaad0-b56a-41dc-8d1f-9d12fc66113f-2019-01-18T170000.000Z
  description: >-
    The pinned ClinGen snapshot records a Definitive autosomal recessive
    BCKDK–branched-chain keto acid dehydrogenase kinase deficiency assertion
    from the Aminoacidopathy Gene Curation Expert Panel.
  evidence:
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Branched-chain ketoacid dehydrogenase kinase (BCKDK) deficiency causes
      branched-chain amino acid (BCAA) depletion and is linked to a
      neurodevelopmental disorder characterized by autism, intellectual
      disability and microcephaly.
    explanation: Independently supports the exact gene-disease relationship represented by the ClinGen assertion.
definitions:
- name: Recessive BCKDK loss-of-function deficiency
  definition_type: OTHER
  description: >-
    A treatable autosomal recessive aminoacidopathy in which biallelic
    loss-of-function BCKDK variants remove inhibitory phosphorylation of BCKDH,
    causing excessive BCAA oxidation, low plasma and CSF BCAAs, and a
    neurodevelopmental disorder.
  evidence:
  - reference: PMID:35216372
    reference_title: Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Hyperactivity of BCKDH and over-consumption of BCAA were demonstrated by
      functional tests in cells transfected with the mutant BCKDK.
    explanation: Defines the loss-of-inhibition biochemical mechanism.
inheritance:
- name: Autosomal recessive inheritance
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  description: >-
    Disease-causing BCKDK deficiency results from biallelic loss-of-function
    variants. This is distinct from the proposed heterozygous gain-of-function
    BCKDK biochemical phenotype with elevated BCAAs.
  evidence:
  - reference: PMID:22956686
    reference_title: Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We focused on the identification of homozygous variants predicted to
      result in loss of protein function, consistent with the presumed mode of
      recessive inheritance.
    explanation: Directly supports recessive inheritance for BCKDK loss-of-function disease.
progression:
- phase: Birth and presymptomatic interval
  age_range: Newborn period through infancy
  notes: >-
    Congenital microcephaly is not typical in the largest cohort. Low BCAAs can
    already be detected retrospectively in newborn dried blood spots, creating
    an opportunity for diagnosis before the neurodevelopmental phenotype is
    established.
  evidence:
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      No microcephaly was observed at birth, but 17/20 developed microcephaly
      during follow-up.
    explanation: Establishes the predominantly postnatal evolution of microcephaly.
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      NBS in DBS identified BCAA levels significantly lower than those of the
      normal population.
    explanation: Shows that the biochemical signature can precede clinical diagnosis.
- phase: Untreated neurodevelopmental disease
  age_range: Infancy through childhood
  notes: >-
    Developmental and language impairment, autism, motor dysfunction, epilepsy,
    postnatal microcephaly, and occasional regression accumulate over childhood.
    The cohort was diagnosed from 8 months to 16 years, demonstrating a wide
    diagnostic delay.
  evidence:
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Patients were diagnosed between 8 months and 16 years (mean: 5.8 years,
      43% female).
    explanation: Defines the observed diagnostic age range.
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Regression was reported in six patients."
    explanation: Documents that loss of previously acquired function can occur.
- phase: Diet-treated follow-up
  age_range: After biochemical and molecular diagnosis
  notes: >-
    Plasma BCAAs generally rise with high-protein intake and BCAA
    supplementation. Motor function, head growth, seizures, speech, and
    psychomotor development may stabilize or improve, with the most favorable
    reports after early treatment. Existing cohorts are small and uncontrolled,
    so treatment cannot be assumed to reverse established disability.
  evidence:
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      motor functions and head circumference stabilized/improved in 13/13 and
      in 11/15 patients, respectively.
    explanation: Quantifies motor and head-growth outcomes in treated patients with follow-up data.
  - reference: PMID:40851941
    reference_title: "BCKDK gene mutations as a rare condition responsible for comorbid neurodevelopmental delay, autism, and epilepsy: a case series of four patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      By initiating a BCAAs-rich regimen, the patients had significant
      improvements in psychomotor and speech development.
    explanation: Adds 2025 case-series evidence for developmental improvement after dietary therapy.
pathophysiology:
- name: BCKDK loss of function
  description: >
    Biallelic loss-of-function variants in BCKDK (frameshift, nonsense, missense,
    or in-frame deletion) reduce or abolish the mitochondrial branched-chain
    ketoacid dehydrogenase kinase. Patient cells show reduced BCKDK mRNA
    (consistent with nonsense-mediated decay), undetectable BCKDK protein, and
    loss of the phospho-E1-alpha (Ser293) signal that normally inactivates BCKDH.
  genes:
  - preferred_term: BCKDK
    term:
      id: hgnc:16902
      label: BCKDK
  molecular_functions:
  - preferred_term: branched-chain ketoacid dehydrogenase kinase activity
    term:
      id: GO:0047323
      label: "[3-methyl-2-oxobutanoate dehydrogenase (acetyl-transferring)] kinase activity"
    modifier: DECREASED
  locations:
  - preferred_term: mitochondrion
    term:
      id: GO:0005739
      label: mitochondrion
  evidence:
  - reference: PMID:22956686
    reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We have identified inactivating mutations in the gene BCKDK (Branched Chain Ketoacid Dehydrogenase Kinase) in consanguineous families with autism, epilepsy, and intellectual disability."
    explanation: "Directly identifies inactivating BCKDK mutations as the cause of the disorder."
  - reference: PMID:22956686
    reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients with homozygous BCKDK mutations display reductions in BCKDK messenger RNA and protein, E1α phosphorylation, and plasma branched-chain amino acids."
    explanation: "Confirms loss of BCKDK mRNA, protein, and E1-alpha phosphorylation in patients with homozygous mutations."
  downstream:
  - target: Constitutive BCKDH activation and excessive BCAA catabolism
    description: >
      Loss of BCKDK-mediated inhibitory phosphorylation of the BCKDH E1-alpha
      subunit leaves the BCKDH complex constitutively active, increasing
      catabolic flux through the rate-limiting step of BCAA degradation.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:22956686
      reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "These data suggest that patients with BCKDK mutations may lack basal, negative regulation of BCKDH activity."
      explanation: "Loss of BCKDK removes basal negative regulation of BCKDH, the direct downstream consequence."
- name: Constitutive BCKDH activation and excessive BCAA catabolism
  description: >
    The branched-chain ketoacid dehydrogenase (BCKDH) complex catalyzes the
    irreversible, rate-limiting step in BCAA catabolism. Without BCKDK-mediated
    phosphorylation, BCKDH activity is unchecked, accelerating the breakdown of
    leucine, isoleucine, and valine.
  biological_processes:
  - preferred_term: branched-chain amino acid catabolic process
    term:
      id: GO:0009083
      label: branched-chain amino acid catabolic process
    modifier: INCREASED
  - preferred_term: protein dephosphorylation of BCKDH E1-alpha
    term:
      id: GO:0006470
      label: protein dephosphorylation
    modifier: INCREASED
  locations:
  - preferred_term: mitochondrion
    term:
      id: GO:0005739
      label: mitochondrion
  evidence:
  - reference: PMID:35216372
    reference_title: "Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Hyperactivity of BCKDH and over-consumption of BCAA were demonstrated by functional tests in cells transfected with the mutant BCKDK."
    explanation: "Functional cell assays directly demonstrate BCKDH hyperactivity and BCAA over-consumption from mutant BCKDK."
  - reference: PMID:27472223
    reference_title: "A Spontaneous Missense Mutation in Branched Chain Keto Acid Dehydrogenase Kinase in the Rat Affects Both the Central and Peripheral Nervous Systems."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "when Ser293 is not phosphorylated, BCKDH activity is unchecked and the levels of the BCAAs will decrease dramatically."
    explanation: "Rat model establishes that loss of Ser293 phosphorylation leaves BCKDH unchecked, dramatically lowering BCAAs."
  downstream:
  - target: Systemic and CSF BCAA depletion
    description: >
      Accelerated BCKDH-mediated catabolism depletes circulating and central
      branched-chain amino acids. BCAAs are essential amino acids that cannot be
      synthesized de novo, so increased catabolism is not compensated by
      synthesis.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:35216372
      reference_title: "Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Plasma and cerebrospinal fluid concentrations of BCAA were markedly reduced."
      explanation: "Directly documents the markedly reduced plasma and CSF BCAA that result from accelerated catabolism."
  - target: Aberrant catabolic flux beyond simple BCAA insufficiency
    description: >
      Beyond depleting circulating and central BCAAs, the constitutively active
      BCKDH complex drives aberrant flux through the BCAA catabolic pathway
      itself. Mouse-model evidence indicates that this excess catabolic flux
      (not just the resulting low BCAA levels) is a mechanistic contributor to
      disease.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:38770403
      reference_title: "Partial suppression of BCAA catabolism as a potential therapy for BCKDK deficiency."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "These data suggest that aberrant flux through the BCAA catabolic pathway, not just BCAA insufficiency, may contribute to disease pathology."
      explanation: "Mouse-model data support that constitutive BCKDH activation drives aberrant catabolic flux that contributes to disease beyond BCAA insufficiency."
- name: Systemic and CSF BCAA depletion
  description: >
    Markedly reduced concentrations of leucine, isoleucine, and valine in plasma
    and cerebrospinal fluid are the biochemical hallmark of BCKDK deficiency.
    Because BCAAs share blood-brain barrier transporters (notably LAT1,
    SLC7A5/SLC3A2) with other large neutral amino acids, low plasma BCAAs also
    perturb brain concentrations of other large neutral amino acids that are
    precursors for neurotransmitters.
  biological_processes:
  - preferred_term: branched-chain amino acid catabolic process
    term:
      id: GO:0009083
      label: branched-chain amino acid catabolic process
    modifier: INCREASED
  - preferred_term: amino acid transmembrane transport across the blood-brain barrier
    term:
      id: GO:0003333
      label: amino acid transmembrane transport
    modifier: DYSREGULATED
  chemical_entities:
  - preferred_term: branched-chain amino acid
    term:
      id: CHEBI:22918
      label: branched-chain amino acid
    modifier: DECREASED
  - preferred_term: leucine
    term:
      id: CHEBI:25017
      label: leucine
    modifier: DECREASED
  - preferred_term: isoleucine
    term:
      id: CHEBI:24898
      label: isoleucine
    modifier: DECREASED
  - preferred_term: valine
    term:
      id: CHEBI:27266
      label: valine
    modifier: DECREASED
  evidence:
  - reference: PMID:22956686
    reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We measured plasma BCAAs in our patients and found that each patient with a homozygous mutation showed notably lower levels of plasma BCAAs than their healthy relatives and with respect to reference ranges"
    explanation: "Directly documents lower plasma BCAAs in patients with homozygous BCKDK mutations."
  - reference: PMID:22956686
    reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Because several of these amino acids are precursors for important neurotransmitters, it remains a possibility that the reduced BCAAs and/or the increased LNAAs contribute to the neurological phenotype."
    explanation: "Mouse brain amino acid profiling links blood-brain barrier transport imbalance and neurotransmitter precursor disturbance to the neurological phenotype."
  downstream:
  - target: Reduced BCAA-derived nitrogen delivery and brain nutrient-stress response
    description: >
      Low systemic BCAAs restrict the BCAA-derived nitrogen reaching the brain
      and alter amino-acid-transporter and integrated-stress-response programs,
      especially under nutrient scarcity.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:41587643
      reference_title: A metabolic basis for motor deficits in mice lacking BCKDK.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Thus, in the non-growing adult constitutive BCKDH activation limits
        BCAA-derived nitrogen delivery to brain and alters AA transporters as
        part of an adaptive ISR during nutrient scarcity.
      explanation: Directly supports reduced BCAA-derived nitrogen delivery to brain in the knockout model.
  - target: Hypovalinemia
    description: Systemic BCAA depletion includes low plasma valine.
    evidence:
    - reference: PMID:22956686
      reference_title: Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        each patient with a homozygous mutation showed notably lower levels of
        plasma BCAAs than their healthy relatives and with respect to reference
        ranges
      explanation: Directly supports low plasma valine as part of the BCAA depletion profile.
  - target: Hypoleucinemia
    description: Systemic BCAA depletion includes low plasma leucine.
    evidence:
    - reference: PMID:22956686
      reference_title: Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        each patient with a homozygous mutation showed notably lower levels of
        plasma BCAAs than their healthy relatives and with respect to reference
        ranges
      explanation: Directly supports low plasma leucine as part of the BCAA depletion profile.
  - target: Hypoisoleucinemia
    description: Systemic BCAA depletion includes low plasma isoleucine.
    evidence:
    - reference: PMID:22956686
      reference_title: Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        each patient with a homozygous mutation showed notably lower levels of
        plasma BCAAs than their healthy relatives and with respect to reference
        ranges
      explanation: Directly supports low plasma isoleucine as part of the BCAA depletion profile.
  - target: Decreased CSF valine concentration
    description: Central BCAA depletion includes decreased CSF valine concentration.
    evidence:
    - reference: PMID:35216372
      reference_title: Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Plasma and cerebrospinal fluid concentrations of BCAA were markedly reduced."
      explanation: Directly supports reduced CSF valine as part of central BCAA depletion.
- name: Reduced BCAA-derived nitrogen delivery and brain nutrient-stress response
  description: >-
    Constitutive peripheral BCAA oxidation limits the circulating precursor pool
    and reduces incorporation of BCAA-derived nitrogen into brain glutamate.
    During fasting, Bckdk-null brain activates the integrated stress response,
    increases Atf4 targets including Slc7a5, and reduces protein synthesis,
    whereas skeletal muscle is comparatively resilient. This supplies a
    mechanistic bridge between systemic amino-acid depletion and neurologic
    vulnerability but does not yet explain every human developmental feature.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  evidence:
  - reference: PMID:41587643
    reference_title: A metabolic basis for motor deficits in mice lacking BCKDK.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      In contrast, Bckdk KO brains exhibited ISR activation during fasting, and
      up-regulation of Atf4 and its target genes, including Slc7a5 mRNA.
    explanation: Demonstrates a brain-selective nutrient-stress response in the knockout model.
  - reference: PMID:41587643
    reference_title: A metabolic basis for motor deficits in mice lacking BCKDK.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      This creates a vulnerability in brain not observed in skeletal muscle.
    explanation: Supports tissue-selective brain vulnerability.
  downstream:
  - target: Neurodevelopmental and epileptic phenotype
    description: >-
      Chronic disruption of brain precursor delivery and stress adaptation
      contributes to motor and neurologic disease, while the full developmental
      causal chain remains incompletely resolved.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    evidence:
    - reference: PMID:41587643
      reference_title: A metabolic basis for motor deficits in mice lacking BCKDK.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        These data provide a metabolic basis for poor motor performance in
        Bckdk KO mice.
      explanation: Connects altered brain nitrogen handling and stress signaling to a neurologic phenotype in vivo.
- name: Neurodevelopmental and epileptic phenotype
  description: >
    The disorder localizes chiefly to the central nervous system, with neurons
    strongly implicated. In mouse studies, cortex-neuron involvement is central
    to the neurological abnormalities, and the spontaneous frogleg rat model
    affects both the central and peripheral nervous systems.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  biological_processes:
  - preferred_term: protein phosphorylation (loss of E1-alpha phosphorylation)
    term:
      id: GO:0006468
      label: protein phosphorylation
    modifier: DECREASED
  evidence:
  - reference: PMID:22956686
    reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Adults developed neurological abnormalities, such as tremors, epileptic seizures, and hindlimb clasping phenotypes observed in some other mouse models of autism spectrum disorders"
    explanation: "Bckdk knockout mice recapitulate the neurological/epileptic phenotype, supporting CNS neuronal involvement."
  - reference: PMID:27472223
    reference_title: "A Spontaneous Missense Mutation in Branched Chain Keto Acid Dehydrogenase Kinase in the Rat Affects Both the Central and Peripheral Nervous Systems."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "The frogleg phenotype shares important characteristics with a previously described Bckdk knockout mouse and with human subjects with Bckdk mutations."
    explanation: "Rat model demonstrates a nervous-system phenotype shared with the mouse model and human patients."
  downstream:
  - target: Autistic behavior
    description: Neurodevelopmental involvement manifests clinically as autistic behavior.
    evidence:
    - reference: PMID:36729635
      reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        16/16 intellectual disability, 17/17 language impairment, 12/17 autism
        spectrum disorder, 9/21 epilepsy
      explanation: Documents autism in the largest BCKDK-deficiency cohort.
  - target: Intellectual disability
    description: Neurodevelopmental involvement manifests clinically as intellectual disability.
    evidence:
    - reference: PMID:36729635
      reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        16/16 intellectual disability, 17/17 language impairment, 12/17 autism
        spectrum disorder, 9/21 epilepsy
      explanation: Documents intellectual disability in all evaluated cohort members.
  - target: Global developmental delay
    description: Neurodevelopmental involvement manifests clinically as global developmental delay.
    evidence:
    - reference: PMID:36729635
      reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "All patients had global neurodevelopmental delay"
      explanation: Documents global developmental delay throughout the 21-patient cohort.
  - target: Epileptic encephalopathy
    description: Neuronal dysfunction manifests as epileptic encephalopathy in severe reported cases.
    evidence:
    - reference: PMID:35216372
      reference_title: Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        In three siblings with severe developmental delays, microcephaly, autism
        spectrum disorder and epileptic encephalopathy
      explanation: Directly documents the severe epileptic-encephalopathy presentation.
  - target: Seizures
    description: Neuronal dysfunction manifests as epileptic seizures.
    evidence:
    - reference: PMID:36729635
      reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        16/16 intellectual disability, 17/17 language impairment, 12/17 autism
        spectrum disorder, 9/21 epilepsy
      explanation: Documents epilepsy in 9 of 21 cohort members.
  - target: Microcephaly
    description: The neurodevelopmental phenotype includes postnatal or progressive microcephaly.
    evidence:
    - reference: PMID:36729635
      reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        No microcephaly was observed at birth, but 17/20 developed microcephaly
        during follow-up.
      explanation: Directly establishes postnatal microcephaly.
  - target: Motor delay
    description: Neurodevelopmental involvement commonly impairs gross motor function.
    evidence:
    - reference: PMID:36729635
      reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        18/21 had gross motor function (GMF) impairment with GMF III or worse in
        5/18
      explanation: Quantifies gross-motor impairment in the largest cohort.
  - target: Language impairment
    description: Language development is prominently affected.
    evidence:
    - reference: PMID:36729635
      reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        16/16 intellectual disability, 17/17 language impairment, 12/17 autism
        spectrum disorder, 9/21 epilepsy
      explanation: Documents language impairment in all evaluated cohort members.
  - target: Developmental regression
    description: Some affected children lose previously acquired skills.
    evidence:
    - reference: PMID:36729635
      reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Regression was reported in six patients."
      explanation: Directly documents regression in the cohort.
  - target: Sensorineural hearing impairment
    description: Sensorineural hearing loss is an uncommon but documented feature.
    evidence:
    - reference: PMID:36729635
      reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        3/21 had sensorineural hearing loss and 4/20 feeding difficulties.
      explanation: Documents sensorineural hearing loss in three cohort members.
  - target: Feeding difficulties
    description: Feeding difficulty occurs in a minority of reported patients.
    evidence:
    - reference: PMID:36729635
      reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        3/21 had sensorineural hearing loss and 4/20 feeding difficulties.
      explanation: Documents feeding difficulty in four evaluated cohort members.
- name: Aberrant catabolic flux beyond simple BCAA insufficiency
  description: >
    Recent mouse-model evidence challenges a purely "BCAA-insufficiency" model.
    In a Bckdk-deficient mouse, enteral BCAA supplementation raised systemic BCAA
    levels but exacerbated neurodevelopmental deficits and failed to correct
    biochemical abnormalities, suggesting that aberrant flux through the BCAA
    catabolic pathway (not just low BCAAs) contributes to disease. Genetic
    re-regulation of catabolism via Dbt haploinsufficiency partially rescued
    biochemical and behavioral phenotypes.
  biological_processes:
  - preferred_term: branched-chain amino acid catabolic process
    term:
      id: GO:0009083
      label: branched-chain amino acid catabolic process
    modifier: INCREASED
  evidence:
  - reference: PMID:38770403
    reference_title: "Partial suppression of BCAA catabolism as a potential therapy for BCKDK deficiency."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "These data suggest that aberrant flux through the BCAA catabolic pathway, not just BCAA insufficiency, may contribute to disease pathology."
    explanation: "Mouse-model data support aberrant catabolic flux as a mechanistic contributor beyond BCAA insufficiency."
  - reference: PMID:38770403
    reference_title: "Partial suppression of BCAA catabolism as a potential therapy for BCKDK deficiency."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "genetic re-regulation of BCAA catabolism, through Dbt haploinsufficiency, partially rescued biochemical and behavioral phenotypes in BCKDK deficient mice."
    explanation: "Genetic re-regulation of downstream BCAA catabolism via Dbt haploinsufficiency partially rescued biochemical and behavioral phenotypes, supporting aberrant catabolic flux (rather than simple BCAA insufficiency) as the disease mechanism and identifying substrate-reduction-style re-regulation as a candidate therapy."
  downstream:
  - target: Neurodevelopmental and epileptic phenotype
    description: Excess pathway flux contributes to behavioral disease independently of the measured systemic BCAA concentration.
    evidence:
    - reference: PMID:38770403
      reference_title: Partial suppression of BCAA catabolism as a potential therapy for BCKDK deficiency.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        genetic re-regulation of BCAA catabolism, through Dbt
        haploinsufficiency, partially rescued biochemical and behavioral
        phenotypes in BCKDK deficient mice.
      explanation: Rescue after partial downstream suppression supports a causal contribution from aberrant flux.
phenotypes:
- name: Autistic behavior
  description: >
    Autism spectrum disorder / autistic features were the presenting feature in
    the original discovery cohort and are reiterated in later case reports.
  phenotype_term:
    preferred_term: Autistic behavior
    term:
      id: HP:0000729
      label: Autistic behavior
  evidence:
  - reference: PMID:22956686
    reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We have identified inactivating mutations in the gene BCKDK (Branched Chain Ketoacid Dehydrogenase Kinase) in consanguineous families with autism, epilepsy, and intellectual disability."
    explanation: "Autism was a defining feature in the consanguineous families with BCKDK mutations."
- name: Intellectual disability
  description: >
    Intellectual disability with severe developmental delay is a core
    neurodevelopmental feature across reported families.
  phenotype_term:
    preferred_term: Intellectual disability
    term:
      id: HP:0001249
      label: Intellectual disability
  evidence:
  - reference: PMID:22956686
    reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Thus, autism presenting with intellectual disability and epilepsy caused by BCKDK mutations represents a potentially treatable syndrome."
    explanation: "Intellectual disability is identified as a core component of the BCKDK-mutation syndrome."
- name: Global developmental delay
  description: >
    Severe developmental delays, including psychomotor delay from the first year
    of life, were reported in an affected sibling series.
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  evidence:
  - reference: PMID:35216372
    reference_title: "Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In three siblings with severe developmental delays, microcephaly, autism spectrum disorder and epileptic encephalopathy, we identified a new homozygous in-frame deletion (c.999_1001delCAC; p.Thr334del) of BCKDK."
    explanation: "Directly documents severe developmental delays in the affected siblings."
- name: Epileptic encephalopathy
  description: >
    Early generalized seizures and epileptic encephalopathy occur; seizure
    control can improve substantially with dietary BCAA therapy.
  phenotype_term:
    preferred_term: Epileptic encephalopathy
    term:
      id: HP:0200134
      label: Epileptic encephalopathy
  evidence:
  - reference: PMID:35216372
    reference_title: "Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In three siblings with severe developmental delays, microcephaly, autism spectrum disorder and epileptic encephalopathy, we identified a new homozygous in-frame deletion (c.999_1001delCAC; p.Thr334del) of BCKDK."
    explanation: "Epileptic encephalopathy is directly documented in the affected siblings."
- name: Seizures
  description: >
    Epileptic seizures are a recurrent feature; in the original report, seizures
    or abnormal EEG were present, and Bckdk knockout mice develop seizures.
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:22956686
    reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "two siblings with autism, intellectual disability (ID), and either seizure or abnormal electroencephalogram (EEG)"
    explanation: "Directly documents seizures (or abnormal EEG) in affected siblings."
- name: Microcephaly
  description: >
    Postnatal/progressive microcephaly is repeatedly reported in human cases and
    is recapitulated in mouse models.
  phenotype_term:
    preferred_term: Microcephaly
    term:
      id: HP:0000252
      label: Microcephaly
  evidence:
  - reference: PMID:35216372
    reference_title: "Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In three siblings with severe developmental delays, microcephaly, autism spectrum disorder and epileptic encephalopathy, we identified a new homozygous in-frame deletion (c.999_1001delCAC; p.Thr334del) of BCKDK."
    explanation: "Microcephaly is directly documented in the affected siblings."
- name: Motor delay
  frequency: VERY_FREQUENT
  description: >-
    Gross-motor impairment is a major component of the developmental phenotype
    and ranges from delayed milestones to severe functional limitation.
  phenotype_term:
    preferred_term: Motor delay
    term:
      id: HP:0001270
      label: Motor delay
  evidence:
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      18/21 had gross motor function (GMF) impairment with GMF III or worse in
      5/18
    explanation: Quantifies motor impairment in the largest reported cohort.
- name: Language impairment
  frequency: VERY_FREQUENT
  description: >-
    Spoken-language development is commonly and substantially impaired.
  phenotype_term:
    preferred_term: Language impairment
    term:
      id: HP:0002463
      label: Language impairment
  evidence:
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      16/16 intellectual disability, 17/17 language impairment, 12/17 autism
      spectrum disorder, 9/21 epilepsy
    explanation: Documents language impairment in every evaluated cohort member.
- name: Developmental regression
  frequency: OCCASIONAL
  description: >-
    A minority of affected children lose previously acquired developmental
    skills.
  phenotype_term:
    preferred_term: Developmental regression
    term:
      id: HP:0002376
      label: Developmental regression
  evidence:
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Regression was reported in six patients."
    explanation: Directly documents regression in six of 21 cohort members.
- name: Sensorineural hearing impairment
  frequency: OCCASIONAL
  description: >-
    Sensorineural hearing loss is an uncommon but recurrently observed
    extra-developmental manifestation.
  phenotype_term:
    preferred_term: Sensorineural hearing impairment
    term:
      id: HP:0000407
      label: Sensorineural hearing impairment
  evidence:
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      3/21 had sensorineural hearing loss and 4/20 feeding difficulties.
    explanation: Documents sensorineural hearing loss in three cohort members.
- name: Feeding difficulties
  frequency: OCCASIONAL
  description: >-
    Feeding difficulty occurs in a minority of affected children and may add to
    nutritional vulnerability.
  phenotype_term:
    preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  evidence:
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      3/21 had sensorineural hearing loss and 4/20 feeding difficulties.
    explanation: Documents feeding difficulties in four evaluated cohort members.
- name: Hypovalinemia
  category: Laboratory
  diagnostic: true
  description: >
    Reduced plasma valine is part of the biochemical hallmark of BCKDK
    deficiency, reflecting accelerated catabolism of this essential
    branched-chain amino acid.
  phenotype_term:
    preferred_term: Hypovalinemia
    term:
      id: HP:0500132
      label: Hypovalinemia
  evidence:
  - reference: PMID:22956686
    reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "each patient with a homozygous mutation showed notably lower levels of plasma BCAAs than their healthy relatives and with respect to reference ranges"
    explanation: "Documents reduced plasma BCAAs (including valine) in affected patients."
- name: Hypoleucinemia
  category: Laboratory
  diagnostic: true
  description: >
    Reduced plasma leucine is part of the low-BCAA biochemical signature of
    BCKDK deficiency.
  phenotype_term:
    preferred_term: Hypoleucinemia
    term:
      id: HP:0500143
      label: Hypoleucinemia
  evidence:
  - reference: PMID:22956686
    reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "each patient with a homozygous mutation showed notably lower levels of plasma BCAAs than their healthy relatives and with respect to reference ranges"
    explanation: "Documents reduced plasma BCAAs (including leucine) in affected patients."
- name: Hypoisoleucinemia
  category: Laboratory
  diagnostic: true
  description: >
    Reduced plasma isoleucine completes the low-BCAA biochemical signature of
    BCKDK deficiency.
  phenotype_term:
    preferred_term: Hypoisoleucinemia
    term:
      id: HP:0500144
      label: Hypoisoleucinemia
  evidence:
  - reference: PMID:22956686
    reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "each patient with a homozygous mutation showed notably lower levels of plasma BCAAs than their healthy relatives and with respect to reference ranges"
    explanation: "Documents reduced plasma BCAAs (including isoleucine) in affected patients."
- name: Decreased CSF valine concentration
  category: Laboratory
  diagnostic: true
  description: >
    Cerebrospinal fluid concentrations of the branched-chain amino acids
    (leucine, isoleucine, and valine) are markedly reduced, reflecting depletion
    of central BCAAs. The bound HP term captures the valine component; HPO does
    not currently provide CSF leucine/isoleucine concentration terms.
  phenotype_term:
    preferred_term: Decreased CSF valine concentration
    term:
      id: HP:0500188
      label: Decreased CSF valine concentration
  evidence:
  - reference: PMID:35216372
    reference_title: "Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Plasma and cerebrospinal fluid concentrations of BCAA were markedly reduced."
    explanation: "Directly documents markedly reduced CSF BCAA, including valine, in affected patients."
biochemical:
- name: Plasma branched-chain amino acids
  presence: DECREASED
  context: >
    Low plasma leucine, isoleucine, and valine are the diagnostic biochemical
    hallmark of BCKDK deficiency. There is no abnormal urinary BCAA excretion or
    organic acid accumulation, distinguishing it from defects that cause BCAA
    overflow. A retrospective review showed that low BCAA values are also
    detectable on newborn dried blood spots, suggesting amenability to newborn
    screening if low (rather than high) BCAA values are actively flagged.
  readouts:
  - target: Systemic and CSF BCAA depletion
    relationship: READOUT_OF
    direction: NEGATIVE
    endpoint_context: DIAGNOSTIC
    interpretation: >
      Low plasma BCAA reports the increased BCKDH-mediated catabolic flux
      resulting from loss of BCKDK inhibitory phosphorylation.
    evidence:
    - reference: PMID:35216372
      reference_title: "Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Plasma and cerebrospinal fluid concentrations of BCAA were markedly reduced."
      explanation: "Reduced plasma/CSF BCAA is the biochemical readout of the underlying catabolic block reversal."
  evidence:
  - reference: PMID:35216372
    reference_title: "Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a retrospective review of the newborn screening results allowed the identification of a strong decrease in BCAA concentrations on dried blood spots, suggesting that BCKDK is a new treatable metabolic disorder probably amenable to newborn screening programs."
    explanation: "Confirms low BCAA on newborn dried blood spots and proposes newborn-screening amenability."
genetic:
- name: BCKDK pathogenic variants
  gene_term:
    preferred_term: BCKDK
    term:
      id: hgnc:16902
      label: BCKDK
  inheritance:
  - name: Autosomal recessive
    evidence:
    - reference: PMID:22956686
      reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "We focused on the identification of homozygous variants predicted to result in loss of protein function, consistent with the presumed mode of recessive inheritance."
      explanation: "Establishes autosomal recessive inheritance with biallelic loss-of-function variants."
  variants:
  - name: p.Arg156* and p.M74fs (null variants)
    description: >
      The original report identified a nonsense variant (C466T; premature stop at
      position 156, p.Arg156*) in family 558 and a single-base deletion
      (c.G222del) causing a frameshift terminating the protein at position 74
      (p.M74fs) in family 18. Both are null, homozygous, loss-of-function
      variants segregating recessively.
    evidence:
    - reference: PMID:22956686
      reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "In family 558, we identified a cytosine-to-thymine substitution in exon 4 (C466T) resulting in a premature stop codon at amino acid position 156, prior to the kinase domain"
      explanation: "Directly identifies the p.Arg156* null variant in family 558."
  - name: p.Arg224Pro (missense)
    description: >
      A missense variant (c.G671C) substituting a highly conserved arginine with
      proline at position 224 was identified in a third family; structural
      modeling predicted disruption of the kinase domain. Missense variants
      caused less severe plasma BCAA reductions than null variants.
    evidence:
    - reference: PMID:22956686
      reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "leading to the substitution of a highly conserved arginine with a proline at position 224 in BCKDK"
      explanation: "Directly identifies the p.Arg224Pro missense variant."
  - name: c.999_1001delCAC (p.Thr334del)
    description: >
      A homozygous in-frame deletion (c.999_1001delCAC; p.Thr334del) was
      identified in three siblings; functional tests in transfected cells
      demonstrated BCKDH hyperactivity and BCAA over-consumption.
    evidence:
    - reference: PMID:35216372
      reference_title: "Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "we identified a new homozygous in-frame deletion (c.999_1001delCAC; p.Thr334del) of BCKDK."
      explanation: "Directly identifies the homozygous p.Thr334del in-frame deletion."
  features: >
    BCKDK deficiency is caused by biallelic loss-of-function variants in BCKDK
    (chromosome 16p11.2), encoding the mitochondrial branched-chain ketoacid
    dehydrogenase kinase. Reported variants include null (nonsense, frameshift),
    missense, and in-frame deletion alleles; null variants produce more profound
    plasma BCAA reductions than missense alleles. Early families were
    consanguineous, consistent with recessive segregation.
  evidence:
  - reference: PMID:22956686
    reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In each of these families, we identified a distinct, null, homozygous mutation in the gene Branched Chain Ketoacid Dehydrogenase Kinase (BCKDK)."
    explanation: "Confirms BCKDK as the causal gene with distinct homozygous null mutations across families."
diagnosis:
- name: Quantitative plasma amino acid analysis
  diagnosis_term:
    preferred_term: clinical laboratory procedure
    term:
      id: NCIT:C25294
      label: Laboratory Procedure
  description: >-
    In a child with otherwise unexplained developmental delay, autism, epilepsy,
    or postnatal microcephaly, quantify plasma leucine, isoleucine, and valine.
    Concordant depression of all three BCAAs is the principal biochemical clue.
  markers: Plasma leucine, isoleucine, and valine
  results: BCAAs below age-appropriate reference ranges support BCKDK deficiency.
  evidence:
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      At diagnosis, BCAA levels (leucine, valine and isoleucine) were below
      reference values in plasma and in CSF.
    explanation: Establishes the low-BCAA biochemical signature at diagnosis.
- name: Cerebrospinal-fluid amino acid analysis
  diagnosis_term:
    preferred_term: clinical laboratory procedure
    term:
      id: NCIT:C25294
      label: Laboratory Procedure
  description: >-
    CSF amino acid analysis can demonstrate central BCAA depletion when lumbar
    puncture is clinically indicated, but it is not required solely to diagnose
    the disorder when plasma biochemistry and molecular testing are conclusive.
  markers: CSF leucine, isoleucine, and valine
  results: Low CSF BCAAs support central amino-acid depletion.
  evidence:
  - reference: PMID:35216372
    reference_title: Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Plasma and cerebrospinal fluid concentrations of BCAA were markedly reduced."
    explanation: Directly supports the CSF biochemical finding.
- name: Molecular confirmation of biallelic BCKDK variants
  diagnosis_term:
    preferred_term: molecular genetic testing
    term:
      id: NCIT:C19770
      label: Molecular Analysis
  description: >-
    Sequence BCKDK through a neurodevelopmental or metabolic gene panel, exome,
    or genome and assess copy-number variation as appropriate. Biallelic
    pathogenic loss-of-function variants confirm the recessive deficiency in a
    compatible biochemical and clinical context.
  results: Biallelic pathogenic BCKDK variants establish the molecular diagnosis.
  evidence:
  - reference: PMID:40851941
    reference_title: "BCKDK gene mutations as a rare condition responsible for comorbid neurodevelopmental delay, autism, and epilepsy: a case series of four patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Therefore, genetic testing was done, and genetic variants compatible with
      BCKDK deficiency were detected.
    explanation: Four additional children were diagnosed after low BCAAs prompted molecular testing.
- name: Candidate newborn dried-blood-spot screening
  diagnosis_term:
    preferred_term: clinical laboratory procedure
    term:
      id: NCIT:C25294
      label: Laboratory Procedure
  description: >-
    Retrospective newborn dried-blood-spot analysis can identify unusually low
    BCAAs before symptoms. This supports candidacy for newborn screening but
    does not by itself establish a universal screening standard or validated
    cutoffs.
  markers: Dried-blood-spot leucine, isoleucine, and valine
  results: BCAA values significantly below the newborn reference population warrant confirmatory testing.
  evidence:
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      NBS in DBS identified BCAA levels significantly lower than those of the
      normal population.
    explanation: Demonstrates retrospective detection of the low-BCAA signature in newborn specimens.
differential_diagnoses:
- name: Maple syrup urine disease
  disease_term:
    preferred_term: maple syrup urine disease
    term:
      id: MONDO:0009563
      label: maple syrup urine disease
  description: >-
    Classic BCKD-complex deficiency produces the biochemical opposite of
    recessive BCKDK deficiency: BCAAs accumulate rather than fall, and
    alloisoleucine is the pathognomonic biochemical discriminator.
  distinguishing_features:
  - Elevated BCAAs and alloisoleucine in maple syrup urine disease
  - Low plasma and CSF BCAAs in recessive BCKDK deficiency
  evidence:
  - reference: PMID:38736638
    reference_title: Computational structural genomics and clinical evidence suggest BCKDK gain-of-function may cause a potentially asymptomatic maple syrup urine disease phenotype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Biochemical evidence for MSUD includes elevated branched-chain amino acids
      (BCAA) and the pathognomonic presence of alloisoleucine.
    explanation: Directly states the biochemical pattern that distinguishes MSUD from BCKDK deficiency.
- name: Heterozygous BCKDK gain-of-function biochemical phenotype
  description: >-
    A proposed heterozygous p.Thr372Arg gain-of-function allele produces
    autosomal dominant elevation of BCAAs and alloisoleucine with a mild or
    asymptomatic MSUD-like course. It is a distinct allelic condition and must
    not be merged with biallelic loss-of-function BCKDK deficiency.
  distinguishing_features:
  - Heterozygous rather than biallelic BCKDK variation
  - Elevated rather than depleted BCAAs
  - Detectable alloisoleucine and often benign clinical course
  evidence:
  - reference: PMID:38736638
    reference_title: Computational structural genomics and clinical evidence suggest BCKDK gain-of-function may cause a potentially asymptomatic maple syrup urine disease phenotype.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The BCKDK variant modeling indicated a gain-of-function which leads to
      impaired BCAA catabolism consistent with the biochemical evidence in this
      cohort.
    explanation: Supports the mechanistically opposite gain-of-function allelic phenotype.
- name: Other genetic neurodevelopmental disorders
  description: >-
    Autism, developmental delay, epilepsy, and microcephaly are nonspecific.
    Concordant low plasma BCAAs followed by biallelic BCKDK findings separates
    this treatable aminoacidopathy from phenotypically overlapping genetic
    neurodevelopmental disorders.
  distinguishing_features:
  - Low leucine, isoleucine, and valine
  - Biallelic pathogenic BCKDK variants
  evidence:
  - reference: PMID:40851941
    reference_title: "BCKDK gene mutations as a rare condition responsible for comorbid neurodevelopmental delay, autism, and epilepsy: a case series of four patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Neuroimaging assessments revealed negligible findings; thus, metabolic
      tests were sent, in which BCAAs were lower than normal limits.
    explanation: Shows how metabolic testing distinguished BCKDK deficiency in children with nonspecific NDD and autism.
- name: Dietary protein insufficiency
  description: >-
    Inadequate protein intake can lower circulating essential amino acids, but
    the discovery cohort did not have protein-deficient diets and retained
    normal fasting concentrations of other essential amino acids.
  distinguishing_features:
  - Dietary history and broader essential-amino-acid pattern
  - Persistent selective BCAA depletion despite adequate protein intake
  - Biallelic pathogenic BCKDK variants
  evidence:
  - reference: PMID:22956686
    reference_title: Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      None of the affected individuals was known to eat a diet deficient in
      protein, as evidenced by their normal fasting plasma levels of the other
      essential amino acids
    explanation: Excludes simple dietary protein deficiency in the original affected families.
treatments:
- name: BCAA-enriched high-protein dietary supplementation
  description: >-
    The principal reported disease-directed intervention is a dietitian-directed
    high-protein diet plus oral leucine, isoleucine, and valine. In the largest
    human cohort, reported intake was at least 2 g protein/kg/day with total BCAA
    supplementation of 100–250 mg/kg/day; plasma BCAAs rose and motor function
    and head growth commonly stabilized or improved. Earlier reports found
    strong seizure control with less complete developmental response. These
    uncontrolled human observations should be interpreted separately from a
    2024 mouse study in which enteral BCAAs raised systemic concentrations but
    worsened neurodevelopmental deficits and failed to correct the modeled
    pathway abnormality.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: amino acid supplementation
    term:
      id: NCIT:C15425
      label: Nutritional Supplementation
    therapeutic_agent:
    - preferred_term: leucine
      term:
        id: CHEBI:25017
        label: leucine
    - preferred_term: isoleucine
      term:
        id: CHEBI:24898
        label: isoleucine
    - preferred_term: valine
      term:
        id: CHEBI:27266
        label: valine
  target_phenotypes:
  - preferred_term: Motor delay
    term:
      id: HP:0001270
      label: Motor delay
  - preferred_term: Microcephaly
    term:
      id: HP:0000252
      label: Microcephaly
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  - preferred_term: Language impairment
    term:
      id: HP:0002463
      label: Language impairment
  target_mechanisms:
  - target: Systemic and CSF BCAA depletion
    treatment_effect: MODULATES
    description: >
      BCAA supplementation replenishes depleted branched-chain amino acids,
      restoring plasma concentrations and improving seizure control.
    evidence:
    - reference: PMID:35216372
      reference_title: "Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Treatment with pharmacological doses of BCAA allowed the restoring of BCAA concentrations and greatly improved seizure control."
      explanation: "BCAA supplementation restored BCAA concentrations and improved seizure control in patients."
  evidence:
  - reference: PMID:35216372
    reference_title: "Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Behavioral and developmental skills of the patients improved to a lesser extent."
    explanation: "Documents the more modest behavioral/developmental response compared with seizure control."
  - reference: PMID:22956686
    reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "by supplementing the diet of human cases with BCAAs, we have been able to normalize their plasma BCAA levels"
    explanation: "Dietary BCAA supplementation normalized plasma BCAA levels in human cases."
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      After treatment with a high-protein diet (≥ 2 g/kg/day) and BCAA
      supplementation (100-250 mg/kg/day), plasma BCAA increased significantly
      (P < 0.001), motor functions and head circumference stabilized/improved in
      13/13 and in 11/15 patients, respectively.
    explanation: Provides cohort-level dosing and biochemical, motor, and head-growth outcomes.
  - reference: PMID:40851941
    reference_title: "BCKDK gene mutations as a rare condition responsible for comorbid neurodevelopmental delay, autism, and epilepsy: a case series of four patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      By initiating a BCAAs-rich regimen, the patients had significant
      improvements in psychomotor and speech development.
    explanation: Adds independent human case-series evidence for psychomotor and language improvement.
  - reference: PMID:38770403
    reference_title: "Partial suppression of BCAA catabolism as a potential therapy for BCKDK deficiency."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "BCAA supplementation exacerbated neurodevelopmental deficits and did not correct biochemical abnormalities despite increasing systemic BCAA levels."
    explanation: "Mouse-model caution that enteral BCAA supplementation alone may be insufficient and can worsen neurodevelopmental outcomes; partial/qualifying evidence on the supplementation strategy."
- name: Metabolic and developmental surveillance
  action_category: MONITORING
  description: >-
    Follow quantitative plasma BCAAs together with growth and head
    circumference, motor and language development, seizure control, feeding,
    and hearing. These are rational response and safety domains from the
    available cohort—not evidence for a validated visit interval—and dietary
    changes should be individualized by a metabolic team and dietitian.
  treatment_term:
    preferred_term: clinical monitoring
    term:
      id: NCIT:C124351
      label: Clinical Evaluation
  evidence:
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      After treatment with a high-protein diet (≥ 2 g/kg/day) and BCAA
      supplementation (100-250 mg/kg/day), plasma BCAA increased significantly
      (P < 0.001), motor functions and head circumference stabilized/improved in
      13/13 and in 11/15 patients, respectively.
    explanation: Identifies plasma BCAAs, motor function, and head growth as observed treatment-response domains.
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      3/21 had sensorineural hearing loss and 4/20 feeding difficulties.
    explanation: Supports inclusion of hearing and feeding in individualized clinical follow-up.
- name: Genetic counseling
  description: >
    Given autosomal recessive inheritance, genetic counseling and recurrence-risk
    assessment are indicated for carrier parents, with carrier and cascade testing
    for at-risk relatives.
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:22956686
    reference_title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We focused on the identification of homozygous variants predicted to result in loss of protein function, consistent with the presumed mode of recessive inheritance."
    explanation: "Establishes recessive inheritance, which underlies the role of genetic counseling and recurrence-risk assessment."
clinical_trials:
- name: NCT05687474 — Baby Detect genomic newborn screening
  phase: NOT_APPLICABLE
  status: COMPLETED
  description: >-
    Completed observational newborn-screening program in the Wallonia-Brussels
    Federation using targeted sequencing from neonatal dried blood spots.
    BCKDK deficiency is included among the program's treatable early-onset
    conditions; this is a screening implementation study, not a therapeutic
    efficacy trial.
  notes: ClinicalTrials.gov recruitment status checked 2026-07-23.
  evidence:
  - reference: clinicaltrials:NCT05687474
    reference_title: "Universal Genomic Newborn Screening in the Wallonia-Brussels Federation: Baby Detect"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Baby Detect Project is an innovative NBS program using a panel of target
      sequencing that aims to identify 126 treatable severe early onset genetic
      diseases at birth caused by 361 genes.
    explanation: Establishes the design and treatable-disease scope of the genomic newborn-screening program.
- name: NCT01238250 — Simons Searchlight
  phase: NOT_APPLICABLE
  status: RECRUITING
  description: >-
    Recruiting international observational registry collecting longitudinal
    medical, behavioral, learning, and developmental information from people
    with rare neurodevelopmental genetic variants. BCKDK is listed among the
    eligible genetic conditions; the study is not an interventional BCKDK trial.
  notes: ClinicalTrials.gov recruitment status checked 2026-07-23.
  evidence:
  - reference: clinicaltrials:NCT01238250
    reference_title: "Online Study of People Who Have Genetic Changes and Features of Autism: Simons Searchlight"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Simons Searchlight is an observational, online, international research
      program for families with rare genetic variants that cause
      neurodevelopmental disorders and may be associated with autism.
    explanation: Establishes the registry's observational design and relevant neurodevelopmental scope.
animal_models:
- species: Mouse (Mus musculus)
  genotype: Bckdk knockout (Bckdk−/−)
  category: Knockout
  associated_phenotypes:
  - Reduced circulating and brain BCAAs
  - Growth retardation
  - Tremor, seizures, and hindlimb clasping
  - Impaired motor coordination during protein restriction
  description: >-
    Constitutive Bckdk-null mice reproduce the biochemical depletion and a
    reversible neurologic phenotype. Recent isotope-tracing work adds impaired
    BCAA-derived nitrogen delivery to brain and nutrient-stress-dependent motor
    dysfunction, while also showing relative skeletal-muscle resilience.
  evidence:
  - reference: PMID:22956686
    reference_title: Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Adults developed neurological abnormalities, such as tremors, epileptic
      seizures, and hindlimb clasping phenotypes observed in some other mouse
      models of autism spectrum disorders
    explanation: Documents the core neurologic phenotype of the knockout mouse.
  - reference: PMID:41587643
    reference_title: A metabolic basis for motor deficits in mice lacking BCKDK.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Bckdk KO showed normal grip strength but poor beam traversal and reduced
      wheel running during protein restriction.
    explanation: Establishes coordination and activity deficits under nutrient stress.
- species: Rat (Rattus norvegicus)
  genotype: Homozygous spontaneous Bckdk p.Gly369Glu frogleg allele
  category: Missense loss-of-function model
  associated_phenotypes:
  - Hindlimb splaying and neuromuscular dysfunction
  - Reduced brain weight and ventricular dilation
  - Seizures
  - Reduced circulating BCAAs
  description: >-
    The autosomal recessive frogleg rat carries a damaging kinase-domain Bckdk
    missense allele, loses BCKDH Ser293 phosphorylation, and develops central
    and peripheral nervous-system abnormalities with marked BCAA depletion.
  evidence:
  - reference: PMID:27472223
    reference_title: A Spontaneous Missense Mutation in Branched Chain Keto Acid Dehydrogenase Kinase in the Rat Affects Both the Central and Peripheral Nervous Systems.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      circulating levels of the BCAAs are reduced by 70-80% in animals
      homozygous for the mutation.
    explanation: Directly quantifies the model's systemic biochemical lesion.
  - reference: PMID:27472223
    reference_title: A Spontaneous Missense Mutation in Branched Chain Keto Acid Dehydrogenase Kinase in the Rat Affects Both the Central and Peripheral Nervous Systems.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      The frogleg phenotype shares important characteristics with a previously
      described Bckdk knockout mouse and with human subjects with Bckdk
      mutations.
    explanation: Supports translational correspondence across rat, mouse, and human disease.
- species: Mouse (Mus musculus)
  genotype: Bckdk deficiency with Dbt haploinsufficiency
  category: Genetic rescue model
  associated_phenotypes:
  - Partial biochemical rescue
  - Partial behavioral rescue
  description: >-
    Reducing dosage of the downstream BCKDH E2 component Dbt partially
    re-regulates excessive BCAA catabolism in Bckdk-deficient mice. The result
    supports catabolic-flux suppression as a preclinical strategy rather than
    establishing a human treatment.
  evidence:
  - reference: PMID:38770403
    reference_title: Partial suppression of BCAA catabolism as a potential therapy for BCKDK deficiency.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      genetic re-regulation of BCAA catabolism, through Dbt
      haploinsufficiency, partially rescued biochemical and behavioral
      phenotypes in BCKDK deficient mice.
    explanation: Directly demonstrates partial genetic rescue of biochemical and behavioral phenotypes.
experimental_models:
- name: Patient-derived BCKDK-deficient iPSC neural progenitors and neurons
  experimental_model_type: IPSC_DERIVED_MODEL
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  cell_source: >-
    Fibroblast-derived iPSCs from two affected sisters and an unaffected brother,
    differentiated through neural progenitor cells into mature neurons
  description: >-
    Patient and control cells were compared across reduced extracellular BCAA
    concentrations. The cultured neural cells showed no major genotype-dependent
    survival, proliferation, morphologic, transcriptional, or metabolic
    phenotype, defining an important negative result and favoring a
    non-cell-autonomous systemic mechanism.
  findings:
  - statement: Cultured BCKDK-deficient neurons did not show a major cell-autonomous phenotype.
    supporting_text: >-
      There were no appreciable differences in gene expression or metabolic
      profiles of these cultured neurons, arguing against a major cell-autonomous
      role for BCKDK in the pathogenesis of the disease.
    evidence:
    - reference: PMID:22956686
      reference_title: Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        There were no appreciable differences in gene expression or metabolic
        profiles of these cultured neurons, arguing against a major
        cell-autonomous role for BCKDK in the pathogenesis of the disease.
      explanation: The patient-derived neural model yielded a negative cell-autonomous result.
  evidence:
  - reference: PMID:22956686
    reference_title: Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      To uncover cellular phenotypes of human cells lacking BCKDK, we generated
      pluripotent stem cells (iPSCs) from the fibroblasts of the healthy brother
      and the two affected sisters from family 558 by means of episomal
      reprogramming
    explanation: Defines the provenance and genotype contrast of the patient-derived model.
- name: Mutant BCKDK transfection functional assay
  experimental_model_type: CELL_LINE
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  cell_source: Cells transfected with the human BCKDK p.Thr334del allele
  description: >-
    Expression of mutant BCKDK was used to test its functional effect on BCKDH
    activity and BCAA consumption.
  modeled_mechanisms:
  - target: Constitutive BCKDH activation and excessive BCAA catabolism
    description: The assay measures loss of BCKDK-mediated restraint on BCKDH.
    evidence:
    - reference: PMID:35216372
      reference_title: Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Hyperactivity of BCKDH and over-consumption of BCAA were demonstrated by
        functional tests in cells transfected with the mutant BCKDK.
      explanation: Direct functional evidence that the allele increases BCKDH activity and BCAA consumption.
  findings:
  - statement: The p.Thr334del allele caused BCKDH hyperactivity and BCAA over-consumption.
    supporting_text: >-
      Hyperactivity of BCKDH and over-consumption of BCAA were demonstrated by
      functional tests in cells transfected with the mutant BCKDK.
    evidence:
    - reference: PMID:35216372
      reference_title: Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Hyperactivity of BCKDH and over-consumption of BCAA were demonstrated by
        functional tests in cells transfected with the mutant BCKDK.
      explanation: Directly supports the functional finding.
  evidence:
  - reference: PMID:35216372
    reference_title: Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Hyperactivity of BCKDH and over-consumption of BCAA were demonstrated by
      functional tests in cells transfected with the mutant BCKDK.
    explanation: Defines the assay and its mechanistic result.
discussions:
- discussion_id: gap_bckdk_newborn_screening_and_early_treatment
  prompt: >-
    Does population newborn screening followed by presymptomatic dietary
    treatment prevent autism, epilepsy, and developmental disability?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - diagnosis#Candidate newborn dried-blood-spot screening
  - treatments#BCAA-enriched high-protein dietary supplementation
  rationale: >-
    Retrospective dried-blood-spot values support biochemical detectability, and
    three children treated before age two had favorable autism outcomes, but the
    cohort is small and uncontrolled. Prospective screening performance,
    cutoffs, false-positive burden, and neurodevelopmental efficacy remain
    unestablished.
  evidence:
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Among cases with follow-up data, none of the three patients starting
      treatment before 2 years of age developed autism at follow-up.
    explanation: Suggests an early-treatment benefit but is based on only three nonrandomized cases.
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      NBS in DBS identified BCAA levels significantly lower than those of the
      normal population.
    explanation: Supports newborn biochemical detectability without establishing program-level screening performance.
- discussion_id: mismatch_human_and_mouse_bcaa_supplementation
  prompt: >-
    Why do reported human cohorts improve with BCAA-rich dietary treatment while
    enteral supplementation worsens neurodevelopmental deficits in one mouse
    model?
  kind: HUMAN_MODEL_MISMATCH
  status: OPEN
  attaches_to:
  - treatments#BCAA-enriched high-protein dietary supplementation
  - pathophysiology#Aberrant catabolic flux beyond simple BCAA insufficiency
  rationale: >-
    Human evidence comes from uncontrolled observational cohorts receiving a
    combined high-protein and BCAA regimen, whereas the mouse experiment tests a
    defined model and enteral supplementation. Species, developmental timing,
    dosing, diet composition, brain delivery, and residual genotype effects may
    explain the divergence.
  evidence:
  - reference: PMID:36729635
    reference_title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      After treatment with a high-protein diet (≥ 2 g/kg/day) and BCAA
      supplementation (100-250 mg/kg/day), plasma BCAA increased significantly
      (P < 0.001), motor functions and head circumference stabilized/improved in
      13/13 and in 11/15 patients, respectively.
    explanation: Summarizes the reported human biochemical and clinical response.
  - reference: PMID:38770403
    reference_title: Partial suppression of BCAA catabolism as a potential therapy for BCKDK deficiency.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      BCAA supplementation exacerbated neurodevelopmental deficits and did not
      correct biochemical abnormalities despite increasing systemic BCAA
      levels.
    explanation: Establishes the opposite outcome in the mouse intervention experiment.
- discussion_id: gap_brain_delivery_and_catabolic_flux
  prompt: >-
    Which mechanism most directly drives human neurodevelopmental disease:
    systemic depletion, impaired BCAA-derived nitrogen delivery, brain
    nutrient-stress signaling, or abnormal downstream catabolic flux?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#Reduced BCAA-derived nitrogen delivery and brain nutrient-stress response
  - pathophysiology#Aberrant catabolic flux beyond simple BCAA insufficiency
  rationale: >-
    New mouse results bridge systemic depletion to brain metabolism, while
    genetic rescue indicates that excess pathway flux matters independently of
    the measured BCAA concentration. Human tissue-level evidence remains absent,
    and patient-derived neurons did not reproduce a major cell-autonomous
    phenotype.
  evidence:
  - reference: PMID:41587643
    reference_title: A metabolic basis for motor deficits in mice lacking BCKDK.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Thus, in the non-growing adult constitutive BCKDH activation limits
      BCAA-derived nitrogen delivery to brain and alters AA transporters as part
      of an adaptive ISR during nutrient scarcity.
    explanation: Demonstrates impaired BCAA-derived nitrogen delivery in vivo.
  - reference: PMID:38770403
    reference_title: Partial suppression of BCAA catabolism as a potential therapy for BCKDK deficiency.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      These data suggest that aberrant flux through the BCAA catabolic pathway,
      not just BCAA insufficiency, may contribute to disease pathology.
    explanation: Establishes the competing or complementary catabolic-flux mechanism.
review_notes: >-
  Full re-review completed 2026-07-23. The modeled disease is specifically
  autosomal recessive BCKDK loss of function with low BCAAs; the proposed
  heterozygous p.Thr372Arg gain-of-function, high-BCAA/alloisoleucine phenotype
  is retained only as an allelic differential and scope boundary. Baby Detect
  and Simons Searchlight are observational studies, not BCKDK therapeutic
  trials. Newborn screening remains a candidate strategy. Dietary benefit in
  uncontrolled human cohorts is presented alongside, but not invalidated by,
  the discordant 2024 mouse supplementation experiment.
references:
- reference: PMID:22956686
  title: "Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy."
- reference: PMID:35216372
  title: "Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy."
- reference: PMID:27472223
  title: "A Spontaneous Missense Mutation in Branched Chain Keto Acid Dehydrogenase Kinase in the Rat Affects Both the Central and Peripheral Nervous Systems."
- reference: PMID:38770403
  title: "Partial suppression of BCAA catabolism as a potential therapy for BCKDK deficiency."
- reference: PMID:36729635
  title: "BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening."
- reference: PMID:38736638
  title: Computational structural genomics and clinical evidence suggest BCKDK gain-of-function may cause a potentially asymptomatic maple syrup urine disease phenotype.
- reference: PMID:40851941
  title: "BCKDK gene mutations as a rare condition responsible for comorbid neurodevelopmental delay, autism, and epilepsy: a case series of four patients."
- reference: PMID:41587643
  title: A metabolic basis for motor deficits in mice lacking BCKDK.
- reference: clinicaltrials:NCT05687474
  title: "Universal Genomic Newborn Screening in the Wallonia-Brussels Federation: Baby Detect"
- reference: clinicaltrials:NCT01238250
  title: "Online Study of People Who Have Genetic Changes and Features of Autism: Simons Searchlight"
datasets:
- accession: geo:GSE309126
  title: Bckdk-knockout and wild-type adult mouse skeletal-muscle RNA sequencing
  description: >-
    Bulk RNA-seq comparing freely fed Bckdk-knockout and wild-type non-growing
    adult male mouse skeletal muscle. The study found few transcriptomic
    differences and should not be interpreted as a human brain-disease dataset.
  data_type: BULK_RNA_SEQ
  publication: PMID:41587643
  notes: >-
    Organism: Mus musculus. GEO. The publication's data-availability statement
    identifies accession GSE309126; analyzed tissue was skeletal muscle.
  evidence:
  - reference: PMID:41587643
    reference_title: A metabolic basis for motor deficits in mice lacking BCKDK.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      RNA sequencing data produced in this study are available in the Gene
      Expression Ominbus database: accession numberGSE309126.
    explanation: The publication directly identifies the deposited RNA-seq accession.
📚

References & Deep Research

References

10
PMID:22956686
Mutations in BCKD-kinase lead to a potentially treatable form of autism with epilepsy.
No top-level findings curated for this source.
PMID:35216372
Novel Loss of Function Variant in BCKDK Causes a Treatable Developmental and Epileptic Encephalopathy.
No top-level findings curated for this source.
PMID:27472223
A Spontaneous Missense Mutation in Branched Chain Keto Acid Dehydrogenase Kinase in the Rat Affects Both the Central and Peripheral Nervous Systems.
No top-level findings curated for this source.
PMID:38770403
Partial suppression of BCAA catabolism as a potential therapy for BCKDK deficiency.
No top-level findings curated for this source.
PMID:36729635
BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening.
No top-level findings curated for this source.
PMID:38736638
Computational structural genomics and clinical evidence suggest BCKDK gain-of-function may cause a potentially asymptomatic maple syrup urine disease phenotype.
No top-level findings curated for this source.
PMID:40851941
BCKDK gene mutations as a rare condition responsible for comorbid neurodevelopmental delay, autism, and epilepsy: a case series of four patients.
No top-level findings curated for this source.
PMID:41587643
A metabolic basis for motor deficits in mice lacking BCKDK.
No top-level findings curated for this source.
clinicaltrials:NCT05687474
Universal Genomic Newborn Screening in the Wallonia-Brussels Federation: Baby Detect
No top-level findings curated for this source.
clinicaltrials:NCT01238250
Online Study of People Who Have Genetic Changes and Features of Autism: Simons Searchlight
No top-level findings curated for this source.

Deep Research

1
Falcon ▸
1. Disease Information
Edison Scientific Literature 28 citations 2026-06-04T10:45:10.373189

1. Disease Information

1.1 Concise overview

BCKDK deficiency is a rare, autosomal recessive neuro-metabolic disorder caused by biallelic loss-of-function variants in BCKDK, the mitochondrial kinase that normally phosphorylates and inhibits the branched-chain α-ketoacid dehydrogenase (BCKDH) complex. Loss of BCKDK removes this inhibitory brake, increasing BCKDH activity and leading to excessive catabolism of leucine, isoleucine, and valine, with low plasma and cerebrospinal fluid (CSF) BCAA concentrations and a neurodevelopmental phenotype characterized by autism spectrum disorder (ASD), intellectual disability/developmental delay, seizures/epileptic encephalopathy, and microcephaly. (novarino2012mutationsinbckdkinase pages 1-2, boemer2022novellossof pages 1-2)

The initial report explicitly framed the condition as a “potentially treatable form of autism with epilepsy” through dietary BCAA repletion, based on human genetics plus rescue in a Bckdk−/− mouse model. (novarino2012mutationsinbckdkinase pages 5-8)

1.2 Key identifiers

The retrieved full-text sources in this run did not explicitly provide OMIM, Orphanet (ORPHA), ICD-10/ICD-11, MeSH, or MONDO identifiers for BCKDK deficiency; therefore, these identifiers cannot be responsibly asserted from the evidence available here. (singh2024computationalstructuralgenomics pages 12-12)

1.3 Synonyms and alternative names (from retrieved literature)

  • Branched-chain ketoacid dehydrogenase kinase deficiency / BCKDK deficiency (babazade2026revealingbckdkdeficiency pages 1-2)
  • BCKD-kinase deficiency (terminology used in the original Science paper title and text) (novarino2012mutationsinbckdkinase pages 5-8)
  • Descriptive framing in the initial report: treatable autism with epilepsy (novarino2012mutationsinbckdkinase pages 5-8)

1.4 Evidence source types

The disease understanding in this report is derived primarily from: - Aggregated disease-level evidence from case series and mechanistic human studies (Science 2012; IJMS 2022) (novarino2012mutationsinbckdkinase pages 5-8, boemer2022novellossof pages 2-6) - Model organism evidence (mouse Bckdk−/−; spontaneous rat model) used to test causal mechanisms and interventions (novarino2012mutationsinbckdkinase pages 5-8, zigler2016aspontaneousmissense pages 2-5)

2. Etiology

2.1 Disease causal factors

  • Genetic cause (primary): biallelic pathogenic variants in BCKDK (loss-of-function), segregating recessively in consanguineous families and sibling sets. (novarino2012mutationsinbckdkinase pages 1-2, boemer2022novellossof pages 2-6)
  • Mechanistic cause: loss of BCKDK-mediated inhibitory phosphorylation of BCKDH E1α leads to increased BCAA catabolic flux and low systemic/CSF BCAAs. (novarino2012mutationsinbckdkinase pages 5-8, zigler2016aspontaneousmissense pages 2-5)

2.2 Risk factors

  • Family history/consanguinity: initial families were consanguineous with recessive segregation, indicating increased risk in consanguineous unions. (novarino2012mutationsinbckdkinase pages 1-2)

No environmental, infectious, or lifestyle risk factors were identified in the retrieved texts as primary causes.

2.3 Protective factors

No genetic or environmental protective factors were described in the retrieved texts.

2.4 Gene–environment interactions

No explicit gene–environment interactions were described in the retrieved texts for BCKDK deficiency.

3. Phenotypes

3.1 Core phenotype spectrum (human)

Across the initial discovery cohort and subsequent reports, core features include: - Neurodevelopmental impairment: developmental delay/intellectual disability with severe language impairment/absent speech. (boemer2022novellossof pages 2-6, babazade2026revealingbckdkdeficiency pages 1-2) - ASD/autistic features: prominent in the initial description and reiterated in later case reports. (novarino2012mutationsinbckdkinase pages 5-8, babazade2026revealingbckdkdeficiency pages 3-5) - Epilepsy / epileptic encephalopathy: early generalized seizures and epileptic encephalopathy in some cases; seizure control can improve with dietary therapy in some reports. (boemer2022novellossof pages 2-6, boemer2022novellossof pages 6-8) - Microcephaly (often progressive/postnatal): repeatedly reported. (boemer2022novellossof pages 2-6, babazade2026revealingbckdkdeficiency pages 3-5)

Frequency data (limited): One literature-review excerpt reports very high frequencies for several features in published cohorts (e.g., global developmental delay and microcephaly reported in most individuals in that summarized cohort), but the underlying cohort composition is not fully verifiable from the excerpt alone; thus, frequencies should be treated cautiously. (babazade2026revealingbckdkdeficiency pages 3-5)

3.2 Age of onset and course

  • Onset is typically infancy/early childhood, with psychomotor delay from the first year reported in a sibling series; regression in the second year occurred in 2/3 siblings in that report. (boemer2022novellossof pages 2-6)
  • The disorder is generally chronic/lifelong, with potential partial responsiveness to nutritional therapy and likely better outcomes with earlier initiation. (babazade2026revealingbckdkdeficiency pages 3-5, boemer2022novellossof pages 6-8)

3.3 Laboratory phenotype

A hallmark is persistently low BCAA concentrations: - In a sibling series, CSF BCAA concentrations were markedly reduced relative to reference ranges (e.g., CSF leucine values such as 29 and 15 vs reference 74–203; CSF isoleucine values such as 13 and 7 vs reference 42–124; CSF valine values such as 62 and 44 vs reference 145–337). (boemer2022novellossof pages 6-8)

3.4 Suggested HPO terms

A structured phenotype-to-ontology mapping is provided in Artifact 01.

Category Feature Suggested ontology term(s) Notes Supporting source
Phenotype Autism spectrum disorder / autistic features HPO: Autism (HP:0000717); Autistic behavior (HP:0000729) Human cases were initially ascertained with autism/ASD together with ID and epilepsy; later reports also describe ASD in affected siblings. (novarino2012mutationsinbckdkinase pages 5-8, novarino2012mutationsinbckdkinase pages 1-2, babazade2026revealingbckdkdeficiency pages 3-5)
Phenotype Developmental delay / intellectual disability HPO: Global developmental delay (HP:0001263); Intellectual disability (HP:0001249) Core neurodevelopmental phenotype across reported families; severe developmental delay and adaptive impairment recur in case series. (novarino2012mutationsinbckdkinase pages 5-8, novarino2012mutationsinbckdkinase pages 1-2, boemer2022novellossof pages 2-6)
Phenotype Epilepsy / seizures HPO: Seizure (HP:0001250); Epileptic encephalopathy (HP:0200134) Early generalized seizures and epileptic encephalopathy were reported; seizure burden improved with treatment in some patients. (boemer2022novellossof pages 2-6, boemer2022novellossof pages 1-2, novarino2012mutationsinbckdkinase pages 5-8)
Phenotype Microcephaly HPO: Microcephaly (HP:0000252); Progressive microcephaly (HP:0000253) Postnatal/progressive microcephaly is a recurrent feature in human cases and mouse models. (boemer2022novellossof pages 2-6, babazade2026revealingbckdkdeficiency pages 3-5, ohl2024partialsuppressionof pages 9-11)
Phenotype Absent speech / severe language impairment HPO: Absent speech (HP:0001344); Severe expressive language delay (HP:0011344) The 2022 sibling series described absent speech; severe speech/language delay is repeatedly noted in case descriptions. (boemer2022novellossof pages 2-6, babazade2026revealingbckdkdeficiency pages 1-2)
Phenotype Motor abnormalities / hindlimb clasping HPO: Abnormality of movement (HP:0100022); Motor delay (HP:0001270) Mouse and rat models show hindlimb clasping/flexion-extension or splaying; in humans, psychomotor delay is prominent. (novarino2012mutationsinbckdkinase pages 5-8, zigler2016aspontaneousmissense pages 2-5, du2022theroleof pages 6-7)
Laboratory abnormality Low plasma/CSF branched-chain amino acids HPO: Decreased circulating branched chain amino acid concentration (suggested); Decreased CSF branched chain amino acid concentration (suggested) Explicit biochemical hallmark: low leucine, isoleucine, and valine in plasma and CSF; newborn DBS can also show low Xle/valine. (boemer2022novellossof pages 6-8, boemer2022novellossof pages 2-6, novarino2012mutationsinbckdkinase pages 1-2)
Mechanism Increased BCKDH activity due to loss of inhibitory phosphorylation GO BP: branched-chain amino acid catabolic process (GO:0009083); protein phosphorylation (GO:0006468) BCKDK loss reduces inhibitory phosphorylation of BCKDH E1α, increasing catabolic flux through BCKDH. (novarino2012mutationsinbckdkinase pages 5-8, zigler2016aspontaneousmissense pages 2-5, ohl2024partialsuppressionof pages 1-2)
Mechanism Mitochondrial involvement GO CC: mitochondrion (GO:0005739); mitochondrial matrix (GO:0005759) BCKDK is mitochondrial; patient fibroblasts and models show mitochondrial defects, and BCKDH regulation occurs in the mitochondrial compartment. (ohl2024partialsuppressionof pages 1-2, bo2024primaryrolesof pages 13-15)
Mechanism Blood-brain barrier transport limitation for BCAA repletion GO BP: amino acid transmembrane transport (GO:0003333) 2024 mouse work suggests enteral BCAA supplementation may not adequately restore CSF/brain BCAA, implicating BBB transport limits; BBB transporters are discussed in the original Science report. (ohl2024partialsuppressionof pages 9-11, novarino2012mutationsinbckdkinase pages 5-8)
Cell type Neuron involvement CL: neuron (CL:0000540); cortical neuron (suggested CL class) Neuronal deficiency is strongly implicated; cortex-neuron restricted Bckdk loss causes neurological abnormalities in mice. (bo2024primaryrolesof pages 13-15)
Anatomy Cerebral cortex / brain UBERON: brain (UBERON:0000955); cerebral cortex (UBERON:0000956); cerebrospinal fluid (UBERON:0001359) Neurologic phenotype localizes chiefly to brain/CNS; low CSF BCAA and cortex-neuron experiments support these anatomy terms. (boemer2022novellossof pages 6-8, bo2024primaryrolesof pages 13-15, zigler2016aspontaneousmissense pages 2-5)
Anatomy Peripheral nervous system UBERON: peripheral nervous system (UBERON:0000010) Rat model demonstrates both central and peripheral nervous system involvement. (zigler2016aspontaneousmissense pages 2-5)

Table: This table maps the main reported clinical and mechanistic features of BCKDK deficiency to suggested ontology terms for phenotype, process, cell type, and anatomy. It is useful for structuring disease-knowledge-base annotations while staying close to the available evidence.

4. Genetic / Molecular Information

4.1 Causal gene

  • BCKDK (branched-chain ketoacid dehydrogenase kinase). (novarino2012mutationsinbckdkinase pages 1-2)

4.2 Pathogenic variants reported in retrieved evidence

Human variants (examples explicitly reported): - p.M74fs, p.Arg156, p.Arg224Pro (initial pedigrees). (novarino2012mutationsinbckdkinase pages 5-8) - c.999_1001delCAC (p.Thr334del)* in 3 siblings; shown by functional assays to reduce phosphorylation of the BCKDH E1α substrate. (boemer2022novellossof pages 2-6)

Model organism variant: - Rat Bckdk G369E (homozygous) associated with loss of Ser293 phosphorylation and low plasma BCAAs. (zigler2016aspontaneousmissense pages 2-5)

4.3 Functional consequence

  • Predominant mechanism is loss of kinase function (reduced inhibitory phosphorylation of BCKDH), causing increased catabolic flux and BCAA depletion. (novarino2012mutationsinbckdkinase pages 5-8, boemer2022novellossof pages 2-6)

4.4 Modifier genes / epigenetics / chromosomal abnormalities

No modifier genes, epigenetic signatures, or recurrent chromosomal abnormalities were described in the retrieved texts.

5. Environmental Information

No specific environmental toxins, lifestyle factors, or infectious triggers were reported in the retrieved texts as causal or modifying factors for BCKDK deficiency.

6. Mechanism / Pathophysiology

6.1 Core biochemical pathway and causal chain

  1. Trigger: biallelic loss-of-function variants in BCKDK. (novarino2012mutationsinbckdkinase pages 1-2, boemer2022novellossof pages 2-6)
  2. Molecular defect: reduced inhibitory phosphorylation of the BCKDH complex E1α subunit (loss of phospho-E1α signal in patient-derived cells; impaired phosphorylation in functional assays). (novarino2012mutationsinbckdkinase pages 5-8, boemer2022novellossof pages 2-6)
  3. Metabolic consequence: increased BCAA catabolism → low plasma and CSF BCAA concentrations; newborn dried blood spots can also show low BCAA-related markers (e.g., Xle and valine). (boemer2022novellossof pages 2-6)
  4. Clinical manifestation: neurodevelopmental disorder with ASD/ID/developmental delay, epilepsy/seizures, and microcephaly. (novarino2012mutationsinbckdkinase pages 5-8, boemer2022novellossof pages 2-6)

6.2 Expanded metabolomic disturbance (recent evidence)

A 2024 mouse-model study challenged a simplistic “only BCAA deficiency” model and reported broader metabolic imbalances in Bckdk−/− mice, including acylcarnitine and TCA-cycle intermediate alterations, and argued that altered flux through the pathway may be central. (ohl2024partialsuppressionof pages 9-11, ohl2024partialsuppressionof pages 1-2)

6.3 CNS access limitation as a mechanistic constraint on therapy

The 2024 mouse-model study also highlighted that enteral BCAA supplementation may raise systemic levels without restoring CSF/brain BCAA levels, consistent with constraints at the blood–brain barrier (BBB) and rapid post-dose disposal, complicating therapeutic strategy. (ohl2024partialsuppressionof pages 9-11, boemer2022novellossof pages 2-6)

6.4 Suggested ontology terms (GO/CL/UBERON/CHEBI)

  • Candidate GO BP/CC, CL, and UBERON suggestions aligned to evidence are summarized in Artifact 01. (bo2024primaryrolesof pages 13-15, ohl2024partialsuppressionof pages 9-11)
  • Key chemicals: leucine, isoleucine, valine (BCAAs). (boemer2022novellossof pages 6-8)

7. Anatomical Structures Affected

7.1 Organ/system level

  • Nervous system (primary): neurodevelopmental phenotype implicating the brain/CNS as the primary affected system. (boemer2022novellossof pages 2-6, novarino2012mutationsinbckdkinase pages 5-8)
  • Peripheral nervous system involvement: supported by a spontaneous rat model affecting both central and peripheral nervous systems. (zigler2016aspontaneousmissense pages 2-5)

7.2 Tissue/cell level

  • Evidence supports a key role for neurons, including neuron-enriched BCKDK expression and cortical neuron involvement in mouse studies (cortex neuron–restricted deficiency causing neurological abnormalities). (bo2024primaryrolesof pages 13-15)

7.3 Subcellular level

  • Mitochondrial compartment involvement is inherent to BCKDH regulation and BCKDK function; patient-derived cells in the 2024 discussion are described as showing mitochondrial defects. (ohl2024partialsuppressionof pages 1-2)

8. Temporal Development

  • Onset: typically infancy/early childhood with early developmental delay and early seizures in severe presentations. (boemer2022novellossof pages 2-6)
  • Progression: can include progressive/postnatal microcephaly and developmental regression in some cases. (boemer2022novellossof pages 2-6)
  • Critical period: the literature review excerpt supports that earlier treatment (before age ~2 years) may be associated with better neurodevelopmental outcomes than later treatment. (babazade2026revealingbckdkdeficiency pages 3-5)

9. Inheritance and Population

9.1 Inheritance

  • Autosomal recessive inheritance is supported by homozygous variants in affected individuals with heterozygous carrier parents (including consanguineous families). (novarino2012mutationsinbckdkinase pages 1-2, boemer2022novellossof pages 1-2)

9.2 Epidemiology

The retrieved full-text evidence in this run did not provide prevalence/incidence estimates. The condition is repeatedly described as very rare, with early reports comprising a small number of families/siblings. (boemer2022novellossof pages 6-8, novarino2012mutationsinbckdkinase pages 1-2)

10. Diagnostics

10.1 Clinical suspicion

Consider BCKDK deficiency in children with combinations of: - ASD/autistic features, global developmental delay/intellectual disability - seizures/epileptic encephalopathy - postnatal/progressive microcephaly especially in contexts of consanguinity or affected siblings. (novarino2012mutationsinbckdkinase pages 1-2, boemer2022novellossof pages 2-6)

10.2 Biochemical testing

  • Plasma BCAAs: low leucine, isoleucine, valine are typical. (novarino2012mutationsinbckdkinase pages 1-2)
  • CSF BCAAs: may be markedly reduced with explicit reference ranges reported in one sibling series (e.g., CSF leucine reference 74–203; isoleucine 42–124; valine 145–337). (boemer2022novellossof pages 6-8)
  • Newborn dried blood spot (DBS): low BCAA-related values can be present, e.g., Xle 84 µmol/L and valine 47 µmol/L in one patient’s newborn screen; similar low values were reported for siblings. (boemer2022novellossof pages 2-6)

10.3 Genetic testing

  • Whole-exome sequencing (WES) has been used to identify homozygous loss-of-function BCKDK variants in affected families, with segregation confirmation by Sanger sequencing. (boemer2022novellossof pages 8-10, novarino2012mutationsinbckdkinase pages 1-2)

10.4 Screening / early detection

  • A key practical point is that newborn screening programs may detect BCKDK deficiency if low BCAA values are actively flagged, because low BCAA values can otherwise be overlooked. (boemer2022novellossof pages 8-10, boemer2022novellossof pages 6-8)

10.5 Differential diagnosis (from mechanistic context)

The initial report contrasts BCKDK deficiency (low BCAAs from increased catabolism) with maple syrup urine disease (MSUD) (high BCAAs/toxic accumulation due to defects in BCKDH complex components). This biochemical directionality (low vs high BCAAs) is a key differentiator. (novarino2012mutationsinbckdkinase pages 1-2)

11. Outcome / Prognosis

11.1 Untreated course

The retrieved evidence supports significant neurodevelopmental morbidity (ASD/ID, seizures, microcephaly) and developmental regression in some individuals. (boemer2022novellossof pages 2-6, novarino2012mutationsinbckdkinase pages 5-8)

11.2 Treatment-modified outcomes

  • In a 3-sibling series, dietary therapy was associated with substantial seizure improvement and reduced hospital admissions (e.g., one child: 10 admissions in the year pre-treatment vs 1 admission during 18 months on therapy). (boemer2022novellossof pages 6-8)
  • Reported developmental/behavioral improvements were more variable and less robust than seizure outcomes. (boemer2022novellossof pages 6-8)

No survival curves, mortality rates, or formal quality-of-life instruments were reported in the retrieved texts.

12. Treatment

12.1 Disease-directed nutritional therapy (current real-world implementation)

High-protein diet plus oral BCAA supplementation (leucine, isoleucine, valine) is the main disease-directed intervention reported. - In a sibling series, protein intake of ~2.5–3 g/kg/day plus BCAA supplementation was titrated; initial doses ~85–125 mg/kg/day each were insufficient, while ~135–195 mg/kg/day each given in divided doses (six times daily) achieved physiological plasma levels. (boemer2022novellossof pages 2-6) - Practical monitoring constraints include rapid post-dose disposal and dependence of measured plasma concentrations on sampling timing; frequent dosing (≥6/day) may be needed. (boemer2022novellossof pages 6-8)

MAXO suggestions (treatment actions): - Dietary supplementation (BCAA supplementation) - High-protein diet therapy - Therapeutic drug monitoring–like biochemical monitoring of plasma amino acids (as an action, not a drug) (boemer2022novellossof pages 6-8, boemer2022novellossof pages 2-6)

12.2 Evidence strength and expert-leaning interpretation

  • The original discovery study provided foundational evidence of potential treatability, supported by dietary rescue experiments in Bckdk−/− mice. (novarino2012mutationsinbckdkinase pages 5-8)
  • A 2024 mouse-model study provides an important caution: enteral BCAA supplementation in Bckdk−/− mice “exacerbated neurodevelopmental deficits” and did not correct key biochemical abnormalities, suggesting that simple BCAA repletion may not address the core metabolic flux disturbance and/or CNS delivery constraints. (ohl2024partialsuppressionof pages 1-2)
  • The same 2024 study proposed an alternative strategy: partial suppression of downstream BCAA catabolism via Dbt haploinsufficiency partially rescued biochemical and behavioral phenotypes in mice. (ohl2024partialsuppressionof pages 9-11)

12.3 Recent developments (2023–2024) relevant to therapy landscape

  • 2024 (preclinical, disease-specific): partial suppression of BCAA catabolism as a potential therapy (mouse genetic approach), and the finding that enteral supplementation may be harmful in the model. (ohl2024partialsuppressionof pages 9-11, ohl2024partialsuppressionof pages 1-2)
  • 2023 (therapeutics in related contexts): potent small-molecule BCKDK inhibitors (e.g., PF-07208254) were developed for cardiometabolic indications and show that BCKDK activity is druggable; however, such inhibitors would be expected to increase BCAA catabolic flux and thus are conceptually opposite to what would be desired for BCKDK deficiency. (flach2023smallmoleculebranchedchain pages 1-2)

12.4 Clinical trials

No interventional clinical trials specifically targeting BCKDK deficiency were identified in the retrieved trial records in this run. Two observational studies retrieved are broad genomic/newborn screening or autism genetics registries rather than BCKDK-deficiency therapeutic trials: - Baby Detect: Genomic Newborn Screening (NCT05687474; observational). (trial record retrieved; see tool output) - Simons Searchlight (NCT01238250; observational autism genetics). (trial record retrieved; see tool output)

13. Prevention

Given autosomal recessive inheritance, prevention focuses on: - Genetic counseling and recurrence risk assessment for carrier parents (supported by segregation in families with heterozygous carriers). (boemer2022novellossof pages 1-2) - Carrier testing for at-risk relatives and cascade testing. - Prenatal or preimplantation genetic testing is logically applicable when the familial pathogenic variant is known; however, specific protocols were not detailed in the retrieved texts. - Secondary prevention / early detection: newborn screening strategies that include thresholds for low BCAA values could enable earlier diagnosis and earlier dietary therapy. (boemer2022novellossof pages 8-10)

14. Other Species / Natural Disease

  • A spontaneous rat model (“frogleg”) with homozygous Bckdk G369E shows CNS and PNS involvement and low BCAAs, representing a naturally occurring disease model. (zigler2016aspontaneousmissense pages 2-5)

15. Model Organisms

15.1 Mouse models

  • Bckdk−/− knockout mouse: shows altered brain amino acids and neurological phenotypes (hindlimb clasping, seizures) and was used for dietary rescue experiments with BCAA-enriched diets in early work. (novarino2012mutationsinbckdkinase pages 5-8)
  • Bckdk−/− mouse (2024 metabolomic/therapeutic interrogation): used to test supplementation versus pathway-flux modification; enteral BCAA supplementation worsened neurodevelopmental outcomes, while Dbt haploinsufficiency partially rescued phenotypes. (ohl2024partialsuppressionof pages 1-2, ohl2024partialsuppressionof pages 9-11)

15.2 Rat models

  • Spontaneous Bckdk G369E rat model with biochemical and neurologic phenotypes affecting CNS and PNS. (zigler2016aspontaneousmissense pages 2-5)

Key statistics and data points (from retrieved studies)

  • Initial human genetic discovery: 3 consanguineous pedigrees with 2 affected individuals each (6 affected). (novarino2012mutationsinbckdkinase pages 5-8)
  • Newborn screening biochemical examples: Xle as low as 84 µmol/L and valine 47 µmol/L on dried blood spot in one affected child. (boemer2022novellossof pages 2-6)
  • CSF BCAA reference ranges used in one report: leucine 74–203, isoleucine 42–124, valine 145–337 (µmol/L). (boemer2022novellossof pages 6-8)
  • Treatment intensity/implementation: in one sibling series, achieving physiologic plasma BCAA required dosing ~135–195 mg/kg/day each BCAA divided into ≥6 doses/day, with protein intake 2.5–3 g/kg/day. (boemer2022novellossof pages 2-6)
  • Outcome proxy: one treated child had 10 hospital admissions in the year before therapy vs 1 admission during 18 months on therapy. (boemer2022novellossof pages 6-8)

Summary table of core findings

A cross-domain structured summary is provided below.

Domain Finding Evidence type (human/mouse/rat) Key details (numbers/doses) Primary source (authors/year/journal) URL
Inheritance BCKDK deficiency is an autosomal recessive disorder caused by biallelic loss-of-function variants in BCKDK Human Initial report: 3 consanguineous pedigrees with 2 affected individuals each (6 affected total); recessive segregation supported by homozygous variants in affected individuals (novarino2012mutationsinbckdkinase pages 5-8, novarino2012mutationsinbckdkinase pages 1-2) Novarino et al., 2012, Science https://doi.org/10.1126/science.1224631
Clinical features Core phenotype includes autism/intellectual disability/epilepsy; later reports expand spectrum to developmental and epileptic encephalopathy, microcephaly, absent speech, psychomotor delay, regression, and neurobehavioral abnormalities Human Science 2012 families: autism, ID, epilepsy (novarino2012mutationsinbckdkinase pages 5-8, novarino2012mutationsinbckdkinase pages 1-2); 2022 siblings: psychomotor delay from first year, subacute regression in second year in 2/3, progressive microcephaly, absent speech, early generalized seizures (boemer2022novellossof pages 2-6, boemer2022novellossof pages 1-2) Novarino et al., 2012, Science; Boemer et al., 2022, Int J Mol Sci https://doi.org/10.1126/science.1224631 ; https://doi.org/10.3390/ijms23042253
Biochemical signature Loss of BCKDK causes reduced phosphorylation/inhibition of BCKDH, increased BCAA catabolism, and low plasma/CSF branched-chain amino acids Human Reduced BCKDK mRNA/protein and loss of phospho-E1α signal in patient cells; markedly reduced plasma BCAA in affected individuals (novarino2012mutationsinbckdkinase pages 1-2, novarino2012mutationsinbckdkinase pages 5-8); 2022 family had severely reduced plasma and CSF BCAA and low newborn-screen dried-blood-spot markers (boemer2022novellossof pages 2-6, boemer2022novellossof pages 1-2) Novarino et al., 2012, Science; Boemer et al., 2022, Int J Mol Sci https://doi.org/10.1126/science.1224631 ; https://doi.org/10.3390/ijms23042253
Pathogenic variants Human pathogenic variants reported include p.M74fs, p.Arg156*, p.Arg224Pro, and p.Thr334del Human p.M74fs, p.Arg156*, p.Arg224Pro identified in 2012 families (novarino2012mutationsinbckdkinase pages 5-8); homozygous in-frame deletion c.999_1001delCAC (p.Thr334del) identified in 3 siblings and shown functionally deleterious (boemer2022novellossof pages 2-6, boemer2022novellossof pages 1-2) Novarino et al., 2012, Science; Boemer et al., 2022, Int J Mol Sci https://doi.org/10.1126/science.1224631 ; https://doi.org/10.3390/ijms23042253
Model organism variant Spontaneous rat model carries Bckdk G369E, a missense loss-of-function variant affecting kinase activity Rat Homozygous G369E segregates with central and peripheral nervous system phenotype; markedly decreased Ser293 phosphorylation and sharply decreased plasma BCAA (zigler2016aspontaneousmissense pages 2-5) Zigler et al., 2016, PLOS ONE https://doi.org/10.1371/journal.pone.0160447
Mouse model Bckdk−/− mice recapitulate neurological disease features and biochemical abnormalities Mouse Altered brain amino acid levels, hindlimb clasping, seizures; rescue experiments used BCAA-enriched diets including 7% BCAA and transition to 2% BCAA diets (novarino2012mutationsinbckdkinase pages 5-8) Novarino et al., 2012, Science https://doi.org/10.1126/science.1224631
Rat model Frogleg rat demonstrates both central and peripheral nervous system involvement from Bckdk dysfunction Rat Phenotype linked to unchecked BCKDH activity, excessive BCAA catabolism, and deficient circulating BCAA; structural modeling predicted disruption of kinase domain/ADP binding (zigler2016aspontaneousmissense pages 2-5) Zigler et al., 2016, PLOS ONE https://doi.org/10.1371/journal.pone.0160447
Treatment evidence BCAA supplementation is the main reported disease-directed therapy; high-protein diet plus oral leucine/isoleucine/valine can restore plasma BCAA and improve seizures Human 2022 sibling series used protein-rich diet 2.5-3 g/kg/day plus oral L-leucine/L-isoleucine/L-valine; initial ~85-125 mg/kg/day each was insufficient, increased to ~135-195 mg/kg/day each in divided doses achieved physiological plasma levels; seizure control greatly improved (boemer2022novellossof pages 2-6, boemer2022novellossof pages 1-2, boemer2022novellossof pages 6-8) Boemer et al., 2022, Int J Mol Sci https://doi.org/10.3390/ijms23042253
Treatment outcomes Clinical benefit appears strongest for seizure control; developmental/behavioral gains are more limited and may depend on early treatment Human One child had 10 hospital admissions in the year before therapy versus 1 admission during 18 months on therapy; Vineland scores improved, especially communication/socialization, but behavioral/developmental gains were less robust than seizure benefit (boemer2022novellossof pages 6-8, babazade2026revealingbckdkdeficiency pages 3-5) Boemer et al., 2022, Int J Mol Sci https://doi.org/10.3390/ijms23042253
Newborn screening relevance Low BCAA on dried blood spots suggests potential newborn-screening detectability Human Retrospective review showed low Xle and valine on NBS; example patient values included Xle 84 µmol/L and Val 47 µmol/L on newborn screening (boemer2022novellossof pages 2-6, boemer2022novellossof pages 1-2) Boemer et al., 2022, Int J Mol Sci https://doi.org/10.3390/ijms23042253
2024 therapeutic caveat Newer mouse work challenges the assumption that enteral BCAA supplementation is sufficient or uniformly beneficial Mouse In Bckdk−/− mice, enteral BCAA supplementation increased systemic BCAA but exacerbated neurodevelopmental deficits and did not correct biochemical abnormalities; CSF/brain BCAA remained low (ohl2024partialsuppressionof pages 1-2, ohl2024partialsuppressionof pages 9-11) Ohl et al., 2024, Mol Genet Metab Rep https://doi.org/10.1016/j.ymgmr.2024.101091
2024 alternative preclinical strategy Partial suppression of downstream BCAA catabolism may be a more effective strategy than simple supplementation Mouse Dbt haploinsufficiency partially rescued microcephaly, neurodevelopmental phenotypes, survival, weight, and many biochemical abnormalities in Bckdk−/− mice (ohl2024partialsuppressionof pages 9-11, ohl2024partialsuppressionof pages 1-2) Ohl et al., 2024, Mol Genet Metab Rep https://doi.org/10.1016/j.ymgmr.2024.101091

Table: This table summarizes core disease characteristics of BCKDK deficiency across human cases and animal models, including inheritance, phenotype, biochemical signature, variants, and treatment evidence. It also highlights the important 2024 preclinical finding that enteral BCAA supplementation may not fully correct brain disease and can worsen some mouse outcomes.

Limitations of this evidence package

  • Formal disease identifiers (OMIM/Orphanet/ICD/MeSH/MONDO) were not present in the retrieved full-text sources for this run; this report therefore cannot cite them.
  • A key 2023 Brain paper on newborn-screening amenability (doi:10.1093/brain/awad010) was listed as unobtainable by the search tool in this run and thus cannot be cited directly here.
  • Published human treatment evidence remains based on small numbers of families/siblings; interpretation should account for phenotype variability, timing of treatment initiation, and challenges of CNS repletion demonstrated in animal models. (boemer2022novellossof pages 6-8, ohl2024partialsuppressionof pages 1-2)

References

  1. (novarino2012mutationsinbckdkinase pages 1-2): Gaia Novarino, Paul El-Fishawy, Hulya Kayserili, Nagwa A. Meguid, Eric M. Scott, Jana Schroth, Jennifer L. Silhavy, Majdi Kara, Rehab O. Khalil, Tawfeg Ben-Omran, A. Gulhan Ercan-Sencicek, Adel F. Hashish, Stephan J. Sanders, Abha R. Gupta, Hebatalla S. Hashem, Dietrich Matern, Stacey Gabriel, Larry Sweetman, Yasmeen Rahimi, Robert A. Harris, Matthew W. State, and Joseph G. Gleeson. Mutations in bckd-kinase lead to a potentially treatable form of autism with epilepsy. Science, 338:394-397, Oct 2012. URL: https://doi.org/10.1126/science.1224631, doi:10.1126/science.1224631. This article has 386 citations and is from a highest quality peer-reviewed journal.

  2. (boemer2022novellossof pages 1-2): François Boemer, Claire Josse, Géraldine Luis, Emmanuel Di Valentin, Jérôme Thiry, Christophe Cello, Jean-Hubert Caberg, Caroline Dadoumont, Julie Harvengt, Aimé Lumaka, Vincent Bours, and François-Guillaume Debray. Novel loss of function variant in bckdk causes a treatable developmental and epileptic encephalopathy. International Journal of Molecular Sciences, 23:2253, Feb 2022. URL: https://doi.org/10.3390/ijms23042253, doi:10.3390/ijms23042253. This article has 14 citations.

  3. (novarino2012mutationsinbckdkinase pages 5-8): Gaia Novarino, Paul El-Fishawy, Hulya Kayserili, Nagwa A. Meguid, Eric M. Scott, Jana Schroth, Jennifer L. Silhavy, Majdi Kara, Rehab O. Khalil, Tawfeg Ben-Omran, A. Gulhan Ercan-Sencicek, Adel F. Hashish, Stephan J. Sanders, Abha R. Gupta, Hebatalla S. Hashem, Dietrich Matern, Stacey Gabriel, Larry Sweetman, Yasmeen Rahimi, Robert A. Harris, Matthew W. State, and Joseph G. Gleeson. Mutations in bckd-kinase lead to a potentially treatable form of autism with epilepsy. Science, 338:394-397, Oct 2012. URL: https://doi.org/10.1126/science.1224631, doi:10.1126/science.1224631. This article has 386 citations and is from a highest quality peer-reviewed journal.

  4. (singh2024computationalstructuralgenomics pages 12-12): Emily Singh, Young‐In Chi, Jessica Kopesky, Michael Zimmerman, Raul Urrutia, Donald Basel, and Jessica Scott Schwoerer. Computational structural genomics and clinical evidence suggest bckdk gain‐of‐function may cause a potentially asymptomatic maple syrup urine disease phenotype. JIMD Reports, 65:144-155, Apr 2024. URL: https://doi.org/10.1002/jmd2.12419, doi:10.1002/jmd2.12419. This article has 2 citations and is from a peer-reviewed journal.

  5. (babazade2026revealingbckdkdeficiency pages 1-2): Hanım Babazade, Başak Günal, Kağan Çalişgan, Esma Uygur, Gizem Durcan, Hüseyin Kılıç, Tanyel Zubarioglu, Mehmet Şerif Cansever, Çiğdem Aktuğlu-Zeybek, and Ertuğrul Kiykim. Revealing bckdk deficiency under autism: a case report, therapeutic outcomes, and literature review. Turkish Archives of Pediatrics, Dec 2026. URL: https://doi.org/10.5152/turkarchpediatr.2025.25325, doi:10.5152/turkarchpediatr.2025.25325. This article has 0 citations.

  6. (boemer2022novellossof pages 2-6): François Boemer, Claire Josse, Géraldine Luis, Emmanuel Di Valentin, Jérôme Thiry, Christophe Cello, Jean-Hubert Caberg, Caroline Dadoumont, Julie Harvengt, Aimé Lumaka, Vincent Bours, and François-Guillaume Debray. Novel loss of function variant in bckdk causes a treatable developmental and epileptic encephalopathy. International Journal of Molecular Sciences, 23:2253, Feb 2022. URL: https://doi.org/10.3390/ijms23042253, doi:10.3390/ijms23042253. This article has 14 citations.

  7. (zigler2016aspontaneousmissense pages 2-5): J. Samuel Zigler, Colin A. Hodgkinson, Megan Wright, Andrew Klise, Olof Sundin, Karl W. Broman, Fielding Hejtmancik, Hao Huang, Bonnie Patek, Yuri Sergeev, Stacey Hose, Cory Brayton, Jiao Xaiodong, David Vasquez, Nicholas Maragakis, Susumu Mori, David Goldman, Ahmet Hoke, and Debasish Sinha. A spontaneous missense mutation in branched chain keto acid dehydrogenase kinase in the rat affects both the central and peripheral nervous systems. PLOS ONE, 11:e0160447, Jul 2016. URL: https://doi.org/10.1371/journal.pone.0160447, doi:10.1371/journal.pone.0160447. This article has 21 citations and is from a peer-reviewed journal.

  8. (babazade2026revealingbckdkdeficiency pages 3-5): Hanım Babazade, Başak Günal, Kağan Çalişgan, Esma Uygur, Gizem Durcan, Hüseyin Kılıç, Tanyel Zubarioglu, Mehmet Şerif Cansever, Çiğdem Aktuğlu-Zeybek, and Ertuğrul Kiykim. Revealing bckdk deficiency under autism: a case report, therapeutic outcomes, and literature review. Turkish Archives of Pediatrics, Dec 2026. URL: https://doi.org/10.5152/turkarchpediatr.2025.25325, doi:10.5152/turkarchpediatr.2025.25325. This article has 0 citations.

  9. (boemer2022novellossof pages 6-8): François Boemer, Claire Josse, Géraldine Luis, Emmanuel Di Valentin, Jérôme Thiry, Christophe Cello, Jean-Hubert Caberg, Caroline Dadoumont, Julie Harvengt, Aimé Lumaka, Vincent Bours, and François-Guillaume Debray. Novel loss of function variant in bckdk causes a treatable developmental and epileptic encephalopathy. International Journal of Molecular Sciences, 23:2253, Feb 2022. URL: https://doi.org/10.3390/ijms23042253, doi:10.3390/ijms23042253. This article has 14 citations.

  10. (ohl2024partialsuppressionof pages 9-11): Laura Ohl, Amanda Kuhs, Ryan Pluck, Emily Durham, Michael Noji, Nathan D Philip, Zoltan Arany, and Rebecca C Ahrens-Nicklas. Partial suppression of bcaa catabolism as a potential therapy for bckdk deficiency. Molecular Genetics and Metabolism Reports, May 2024. URL: https://doi.org/10.1016/j.ymgmr.2024.101091, doi:10.1016/j.ymgmr.2024.101091. This article has 8 citations.

  11. (du2022theroleof pages 6-7): Chuang Du, Wen-Jie Liu, Jing Yang, Shan-Shan Zhao, and Hui-Xin Liu. The role of branched-chain amino acids and branched-chain α-keto acid dehydrogenase kinase in metabolic disorders. Frontiers in Nutrition, Jul 2022. URL: https://doi.org/10.3389/fnut.2022.932670, doi:10.3389/fnut.2022.932670. This article has 94 citations.

  12. (ohl2024partialsuppressionof pages 1-2): Laura Ohl, Amanda Kuhs, Ryan Pluck, Emily Durham, Michael Noji, Nathan D Philip, Zoltan Arany, and Rebecca C Ahrens-Nicklas. Partial suppression of bcaa catabolism as a potential therapy for bckdk deficiency. Molecular Genetics and Metabolism Reports, May 2024. URL: https://doi.org/10.1016/j.ymgmr.2024.101091, doi:10.1016/j.ymgmr.2024.101091. This article has 8 citations.

  13. (bo2024primaryrolesof pages 13-15): Tomoki Bo and Junichi Fujii. Primary roles of branched chain amino acids (bcaas) and their metabolism in physiology and metabolic disorders. Molecules, 30:56, Dec 2024. URL: https://doi.org/10.3390/molecules30010056, doi:10.3390/molecules30010056. This article has 56 citations.

  14. (boemer2022novellossof pages 8-10): François Boemer, Claire Josse, Géraldine Luis, Emmanuel Di Valentin, Jérôme Thiry, Christophe Cello, Jean-Hubert Caberg, Caroline Dadoumont, Julie Harvengt, Aimé Lumaka, Vincent Bours, and François-Guillaume Debray. Novel loss of function variant in bckdk causes a treatable developmental and epileptic encephalopathy. International Journal of Molecular Sciences, 23:2253, Feb 2022. URL: https://doi.org/10.3390/ijms23042253, doi:10.3390/ijms23042253. This article has 14 citations.

  15. (flach2023smallmoleculebranchedchain pages 1-2): Rachel J. Roth Flach, Eliza Bollinger, Allan R. Reyes, Brigitte Laforest, Bethany L. Kormos, Shenping Liu, Matthew R. Reese, Luis A. Martinez Alsina, Leanne Buzon, Yuan Zhang, Bruce Bechle, Amy Rosado, Parag V. Sahasrabudhe, John Knafels, Samit K. Bhattacharya, Kiyoyuki Omoto, John C. Stansfield, Liam D. Hurley, LouJin Song, Lina Luo, Susanne B. Breitkopf, Mara Monetti, Teresa Cunio, Brendan Tierney, Frank J. Geoly, Jake Delmore, C. Parker Siddall, Liang Xue, Ka N. Yip, Amit S. Kalgutkar, Russell A. Miller, Bei B. Zhang, and Kevin J. Filipski. Small molecule branched-chain ketoacid dehydrogenase kinase (bdk) inhibitors with opposing effects on bdk protein levels. Nature Communications, Aug 2023. URL: https://doi.org/10.1038/s41467-023-40536-y, doi:10.1038/s41467-023-40536-y. This article has 34 citations and is from a highest quality peer-reviewed journal.

Artifacts