Lipoyl transferase 1 deficiency (OMIM 616299) is a rare autosomal recessive mitochondrial disorder caused by biallelic mutations in LIPT1, encoding lipoyltransferase 1. LIPT1 catalyzes the final step in the mitochondrial lipoylation pathway, transferring lipoyl groups from lipoyl-GCSH to the E2 subunits of alpha-ketoacid dehydrogenases (pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, and branched-chain ketoacid dehydrogenase). Critically, LIPT1 deficiency spares the glycine cleavage system, as GCSH is lipoylated upstream by the LIPT2-LIAS pathway. This results in combined dehydrogenase deficiency with lactic acidosis but typically normal glycine levels, distinguishing it biochemically from LIPT2 and LIAS deficiency. Clinical presentation includes Leigh-like encephalopathy, early-onset seizures, psychomotor retardation, abnormal muscle tone, severe lactic acidosis, and occasionally syndromic congenital sideroblastic anemia. Onset is neonatal to early infantile. Metabolic decompensation during febrile illness may precipitate acute neurological deterioration.
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name: Lipoyl Transferase 1 Deficiency
creation_date: '2026-02-13T00:59:22Z'
updated_date: '2026-05-21T04:25:34Z'
category: Mendelian
description: >
Lipoyl transferase 1 deficiency (OMIM 616299) is a rare autosomal recessive
mitochondrial disorder caused by biallelic mutations in LIPT1, encoding
lipoyltransferase 1. LIPT1 catalyzes the final step in the mitochondrial
lipoylation pathway, transferring lipoyl groups from lipoyl-GCSH to the E2
subunits of alpha-ketoacid dehydrogenases (pyruvate dehydrogenase,
alpha-ketoglutarate dehydrogenase, and branched-chain ketoacid dehydrogenase).
Critically, LIPT1 deficiency spares the glycine cleavage system, as GCSH is
lipoylated upstream by the LIPT2-LIAS pathway. This results in combined
dehydrogenase deficiency with lactic acidosis but typically normal glycine
levels, distinguishing it biochemically from LIPT2 and LIAS deficiency.
Clinical presentation includes Leigh-like encephalopathy, early-onset
seizures, psychomotor retardation, abnormal muscle tone, severe lactic
acidosis, and occasionally syndromic congenital sideroblastic anemia. Onset
is neonatal to early infantile. Metabolic decompensation during febrile
illness may precipitate acute neurological deterioration.
disease_term:
preferred_term: lipoyl transferase 1 deficiency
term:
id: MONDO:0014576
label: lipoyl transferase 1 deficiency
parents:
- Mitochondrial lipoylation defect
- Leigh syndrome spectrum
inheritance:
- name: Autosomal recessive
inheritance_term:
preferred_term: Autosomal recessive inheritance
term:
id: HP:0000007
label: Autosomal recessive inheritance
description: >
LIPT1 deficiency follows autosomal recessive inheritance with biallelic
mutations in LIPT1. Both compound heterozygous and homozygous mutations
have been reported.
evidence:
- reference: PMID:24341803
reference_title: "Mutations in human lipoyltransferase gene LIPT1 cause a Leigh disease with secondary deficiency for pyruvate and alpha-ketoglutarate dehydrogenase."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Exome sequencing identified two heterozygous mutations (c.875C > G and
c.535A > G) in the LIPT1 gene
explanation: >-
Index case identified by exome sequencing with compound heterozygous
LIPT1 mutations, consistent with autosomal recessive inheritance.
- reference: PMID:29681092
reference_title: "LIPT1 deficiency presenting as early infantile epileptic encephalopathy, Leigh disease, and secondary pyruvate dehydrogenase complex deficiency."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Exome sequencing implicated compound heterozygous LIPT1 pathogenic
variants
explanation: >-
Fifth reported case also had compound heterozygous variants, confirming
autosomal recessive inheritance pattern.
- reference: PMID:24256811
reference_title: "Mutations in the lipoyltransferase LIPT1 gene cause a fatal disease associated with a specific lipoylation defect of the 2-ketoacid dehydrogenase complexes."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Sequence analysis of the human LIPT1 identified two heterozygous
missense mutations (c.212C>T and c.292C>G), segregating in different
alleles
explanation: >-
Second independent case with compound heterozygous mutations
segregating on different alleles confirms recessive inheritance.
prevalence:
- population: Global reported patients
percentage: Unknown (at least 6 reported patients by 2024)
notes: >-
No population-based prevalence study was identified. By 2018, the PubMed
literature cited four patients from three families and described a fifth
case; a 2024 report described an additional patient with a homozygous LIPT1
variant and syndromic congenital sideroblastic anemia.
evidence:
- reference: PMID:29681092
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Pathogenic variants in LIPT1 gene have recently been described in four
patients from three families, commonly presenting with severe lactic
acidosis resulting in neonatal death and/or poor neurocognitive outcomes.
explanation: >-
This abstract summarizes the early literature and provides an explicit
reported-case count for LIPT1 deficiency.
- reference: PMID:29681092
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
We describe the fifth case of LIPT1 deficiency, whose phenotype
progressed to that of an early infantile epileptic encephalopathy, which
is novel compared to previously described patients whom we will review.
explanation: >-
The same report extends the published total to five cases, supporting an
unknown but extremely low prevalence designation.
- reference: PMID:39547509
reference_title: "Engineered bacterial lipoate protein ligase A (lplA) restores lipoylation in cell models of lipoylation deficiency."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
a patient with a homozygous c.212C>T variant LIPT1 with a previously
uncharacterized syndromic congenital sideroblastic anemia.
explanation: >-
This 2024 report adds another described patient with biallelic LIPT1
disease and an expanded hematologic phenotype.
pathophysiology:
- name: Defective lipoyl relay via LIPT1 deficiency
description: >
LIPT1 encodes lipoyltransferase 1, which transfers lipoyl groups from
lipoyl-GCSH to the E2 subunits of pyruvate dehydrogenase, alpha-ketoglutarate
dehydrogenase, and branched-chain ketoacid dehydrogenase. This is the final
step in the mitochondrial lipoylation pathway. Crucially, LIPT1 is not
required for lipoylation of GCSH itself, so the glycine cleavage system
remains functional. This explains the distinctive biochemical signature:
combined dehydrogenase deficiency with lactic acidosis but preserved glycine
cleavage and normal glycine levels. The clinical consequence is a Leigh-like
encephalopathy driven by energy failure rather than the combined energy
failure plus glycine toxicity seen in LIPT2 and LIAS deficiency.
genes:
- preferred_term: LIPT1
term:
id: hgnc:29569
label: LIPT1
gene:
preferred_term: LIPT1
description: Lipoyltransferase 1, transfers lipoyl groups from lipoyl-GCSH to E2 subunits of alpha-ketoacid dehydrogenases.
modifier: DECREASED
term:
id: hgnc:29569
label: LIPT1
cell_types:
- preferred_term: Neuron
term:
id: CL:0000540
label: neuron
biological_processes:
- preferred_term: Protein lipoylation
modifier: DECREASED
term:
id: GO:0009249
label: protein lipoylation
downstream:
- target: Combined alpha-ketoacid dehydrogenase deficiency with spared glycine cleavage
description: >-
Loss of LIPT1-mediated lipoyl transfer prevents lipoylation of
alpha-ketoacid dehydrogenase E2 subunits while sparing GCSH-dependent
glycine cleavage.
causal_link_type: DIRECT
evidence:
- reference: PMID:32508887
reference_title: "Progress in the Enzymology of the Mitochondrial Diseases of Lipoic Acid Requiring Enzymes."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
The two dehydrogenase proteins lack lipoylation because LIPT1 is the
enzyme that transfers lipoyl groups from lipoyl-GCSH to the
dehydrogenase proteins.
explanation: >-
The review directly connects LIPT1 loss to failed lipoyl transfer to
the dehydrogenase E2 subunits.
- target: Lipoylated dehydrogenase E2 subunits
description: >-
Loss of LIPT1-mediated lipoyl transfer directly reduces lipoylated PDH
E2 and alpha-KGDH E2 subunits in patient-derived cells.
causal_link_type: DIRECT
- target: Erythroid lipoylation-deficient proliferation defect
description: >-
A homozygous LIPT1 sideroblastic anemia allele causes a
lipoylation-deficient phenotype and impaired low-glucose proliferation in
erythroid-lineage cells.
causal_link_type: DIRECT
evidence:
- reference: PMID:39547509
reference_title: "Engineered bacterial lipoate protein ligase A (lplA) restores lipoylation in cell models of lipoylation deficiency."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
K562 erythroleukemia cells engineered to harbor this missense LIPT1
allele recapitulate the lipoylation-deficient phenotype and exhibit
impaired proliferation in low glucose that is completely restored by
engineered lplA.
explanation: >-
Erythroid-lineage cells carrying the LIPT1 variant show the
lipoylation-deficient cellular phenotype and impaired proliferation.
evidence:
- reference: PMID:24256811
reference_title: "Mutations in the lipoyltransferase LIPT1 gene cause a fatal disease associated with a specific lipoylation defect of the 2-ketoacid dehydrogenase complexes."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
Immunostaining analysis showed that lipoylated E2-PDH and E2-KGDH
were extremely reduced in this patient
explanation: >-
Direct demonstration that LIPT1 mutations cause loss of lipoylation
on E2 subunits of ketoacid dehydrogenases.
- reference: PMID:24341803
reference_title: "Mutations in human lipoyltransferase gene LIPT1 cause a Leigh disease with secondary deficiency for pyruvate and alpha-ketoglutarate dehydrogenase."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
Anti-lipoic acid antibodies revealed absent expression of PDH E2, BCKDH
E2 and α-KGDH E2 subunits
explanation: >-
Fibroblast studies confirmed absent lipoylation of all three E2
subunits in the index case.
- reference: PMID:32508887
reference_title: "Progress in the Enzymology of the Mitochondrial Diseases of Lipoic Acid Requiring Enzymes."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
the physiological role of LIPT1 is in transfer of lipoic acid moieties
from one protein to another
explanation: >-
Review clarifying that LIPT1 functions as an amidotransferase
relaying lipoyl groups from GCSH to dehydrogenase E2 subunits.
- reference: PMID:39199267
reference_title: "A Multi-Target Pharmacological Correction of a Lipoyltransferase LIPT1 Gene Mutation in Patient-Derived Cellular Models."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
absent expression of lipoylated pyruvate dehydrogenase E2 (PDH E2) and
alpha-ketoglutarate dehydrogenase E2 (α-KGDH E2) subunits
explanation: >-
Western blot of LIPT1-deficient fibroblasts showed absent lipoylation
of PDH E2 and alpha-KGDH E2, confirming the lipoyl relay defect.
- name: Combined alpha-ketoacid dehydrogenase deficiency with spared glycine cleavage
description: >
Loss of LIPT1 function impairs lipoylation of the E2 subunits of PDHc,
alpha-KGDHc, and BCKDHc, causing combined dehydrogenase deficiency with
lactic acidosis and elevation of alpha-ketoacids. However, the glycine
cleavage system H protein (GCSH) is lipoylated upstream by the LIPT2-LIAS
pathway and does not require LIPT1 for its own lipoylation, so glycine
cleavage is preserved and glycine levels remain normal or near-normal.
biological_processes:
- preferred_term: Tricarboxylic acid cycle
modifier: DECREASED
term:
id: GO:0006099
label: tricarboxylic acid cycle
molecular_functions:
- preferred_term: pyruvate dehydrogenase (acetyl-transferring) activity
modifier: DECREASED
term:
id: GO:0004739
label: pyruvate dehydrogenase (acetyl-transferring) activity
cellular_components:
- preferred_term: Pyruvate dehydrogenase complex
term:
id: GO:0045254
label: pyruvate dehydrogenase complex
evidence:
- reference: PMID:24256811
reference_title: "Mutations in the lipoyltransferase LIPT1 gene cause a fatal disease associated with a specific lipoylation defect of the 2-ketoacid dehydrogenase complexes."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
the absence of glycine elevation, the normal activity of the glycine
cleavage system and the normal lipoylation of the H protein suggested
a defect of lipoic acid transfer to particular proteins rather than a
general impairment of lipoic acid biosynthesis
explanation: >-
Key biochemical finding distinguishing LIPT1 from LIAS/LIPT2
deficiency: glycine cleavage is preserved because GCSH lipoylation
is intact.
- reference: PMID:32508887
reference_title: "Progress in the Enzymology of the Mitochondrial Diseases of Lipoic Acid Requiring Enzymes."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Patients that display absent or low lipoylation of all three enzymes
have mutations in either of two genes LIAS or LIPT2 whereas patients
that retain glycine cleavage activity are mutant in a third gene, LIPT1
explanation: >-
Review explains the biochemical basis for classification of lipoylation
disorders by glycine cleavage status.
- reference: PMID:32508887
reference_title: "Progress in the Enzymology of the Mitochondrial Diseases of Lipoic Acid Requiring Enzymes."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
LIPT1 patients generally suffer only the respiratory and muscle
weakness problems because GCSH is lipoylated and glycine is cleaved
explanation: >-
Confirms that LIPT1 patients retain GCSH lipoylation and therefore
glycine cleavage activity, sparing them from glycine accumulation.
downstream:
- target: Lactic acidosis
description: >-
Reduced pyruvate dehydrogenase activity causes pyruvate accumulation and
diversion to lactate.
causal_link_type: DIRECT
evidence:
- reference: PMID:32508887
reference_title: "Progress in the Enzymology of the Mitochondrial Diseases of Lipoic Acid Requiring Enzymes."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
the presence of very high levels of lactate (resulting from reduction
of the pyruvate that accumulates due to loss pyruvate dehydrogenase
activity)
explanation: >-
The review directly links loss of pyruvate dehydrogenase activity to
lactate accumulation in lipoic-acid metabolism disorders.
- target: Pyruvate and alpha-ketoglutarate dehydrogenase activity
description: >-
Failed lipoylation directly lowers pyruvate dehydrogenase and
alpha-ketoglutarate dehydrogenase activities.
causal_link_type: DIRECT
- target: Glycine
description: >-
Preserved GCSH lipoylation and glycine cleavage keep glycine normal or
near-normal in LIPT1 deficiency.
causal_link_type: DIRECT
- target: Increased urine lactate, ketoglutarate, and 2-oxoacid levels
description: >-
Reduced 2-ketoacid dehydrogenase activity produces increased urinary
lactate, ketoglutarate, and 2-oxoacid metabolites.
causal_link_type: DIRECT
- target: Mitochondrial bioenergetic failure and lipid peroxidation
description: >-
Reduced PDH and alpha-KGDH activities impair cellular bioenergetics and
are associated with iron accumulation and lipid peroxidation in
LIPT1-deficient patient-derived cells.
causal_link_type: DIRECT
evidence:
- reference: PMID:39199267
reference_title: "A Multi-Target Pharmacological Correction of a Lipoyltransferase LIPT1 Gene Mutation in Patient-Derived Cellular Models."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
Accordingly, activities of PDH and α-KGDH were markedly reduced,
associated with cell bioenergetics failure, iron accumulation, and
lipid peroxidation.
explanation: >-
Patient-derived fibroblast data directly connect reduced dehydrogenase
activity to bioenergetic failure and oxidative injury.
- name: Mitochondrial bioenergetic failure and lipid peroxidation
description: >
LIPT1-deficient patient-derived fibroblasts show reduced PDH and
alpha-KGDH activities with cellular bioenergetic failure, iron accumulation,
and lipid peroxidation. This secondary mitochondrial stress extends the
enzymatic defect beyond protein lipoylation into a measurable cellular
injury state.
cell_types:
- preferred_term: fibroblast
term:
id: CL:0000057
label: fibroblast
biological_processes:
- preferred_term: cellular respiration
modifier: DECREASED
term:
id: GO:0045333
label: cellular respiration
- preferred_term: oxidative phosphorylation
modifier: DECREASED
term:
id: GO:0006119
label: oxidative phosphorylation
evidence:
- reference: PMID:39199267
reference_title: "A Multi-Target Pharmacological Correction of a Lipoyltransferase LIPT1 Gene Mutation in Patient-Derived Cellular Models."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
Accordingly, activities of PDH and α-KGDH were markedly reduced,
associated with cell bioenergetics failure, iron accumulation, and lipid
peroxidation.
explanation: >-
Patient-derived LIPT1 fibroblast models show the downstream bioenergetic
and oxidative injury state.
downstream:
- target: Seizures
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
intermediate_mechanisms:
- Bioenergetic failure in neuronal cells contributes to early-onset epileptic encephalopathy.
description: Severe mitochondrial energy failure contributes to seizures in reported LIPT1 deficiency.
- target: Global developmental delay
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
intermediate_mechanisms:
- Impaired cellular respiration in developing neural tissue disrupts psychomotor development.
description: LIPT1-related mitochondrial dysfunction contributes to psychomotor retardation and poor neurocognitive outcomes.
- target: Abnormal muscle tone
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
intermediate_mechanisms:
- Mitochondrial energy failure in the nervous system and muscle disrupts motor tone.
description: Abnormal muscle tone is reported as part of the LIPT1 deficiency clinical spectrum.
- name: Erythroid lipoylation-deficient proliferation defect
description: >
The LIPT1 c.212C>T sideroblastic anemia allele recapitulates a
lipoylation-deficient phenotype in erythroid-lineage cells and impairs
proliferation under low-glucose conditions, linking defective mitochondrial
lipoylation to the hematologic presentation.
genes:
- preferred_term: LIPT1
term:
id: hgnc:29569
label: LIPT1
cell_types:
- preferred_term: erythroid lineage cell
term:
id: CL:0000764
label: erythroid lineage cell
biological_processes:
- preferred_term: cell population proliferation
modifier: DECREASED
term:
id: GO:0008283
label: cell population proliferation
evidence:
- reference: PMID:39547509
reference_title: "Engineered bacterial lipoate protein ligase A (lplA) restores lipoylation in cell models of lipoylation deficiency."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
K562 erythroleukemia cells engineered to harbor this missense LIPT1
allele recapitulate the lipoylation-deficient phenotype and exhibit
impaired proliferation in low glucose that is completely restored by
engineered lplA.
explanation: >-
Erythroid-lineage cell modeling supports a LIPT1-dependent
lipoylation-deficient proliferation defect.
downstream:
- target: Sideroblastic anemia
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
intermediate_mechanisms:
- Erythroid lipoylation deficiency impairs mitochondrial metabolism and proliferation.
description: A homozygous LIPT1 variant has been reported with syndromic congenital sideroblastic anemia.
evidence:
- reference: PMID:39547509
reference_title: "Engineered bacterial lipoate protein ligase A (lplA) restores lipoylation in cell models of lipoylation deficiency."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
a patient with a homozygous c.212C>T variant LIPT1 with a previously
uncharacterized syndromic congenital sideroblastic anemia.
explanation: >-
Clinical report links the same LIPT1 allele to syndromic congenital
sideroblastic anemia.
phenotypes:
- name: Lactic acidosis
description: >
Severe lactic acidosis due to combined pyruvate dehydrogenase and
alpha-ketoglutarate dehydrogenase deficiency.
frequency: OBLIGATE
phenotype_term:
preferred_term: Congenital lactic acidosis
term:
id: HP:0004902
label: Congenital lactic acidosis
evidence:
- reference: PMID:24256811
reference_title: "Mutations in the lipoyltransferase LIPT1 gene cause a fatal disease associated with a specific lipoylation defect of the 2-ketoacid dehydrogenase complexes."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
a patient with an early onset fatal lactic acidosis presenting a
biochemical phenotype compatible with a combined defect of pyruvate
dehydrogenase (PDHC) and 2-ketoglutarate dehydrogenase (2-KGDH)
activities
explanation: >-
Fatal lactic acidosis was the presenting feature of the second
reported LIPT1 patient.
- reference: PMID:24341803
reference_title: "Mutations in human lipoyltransferase gene LIPT1 cause a Leigh disease with secondary deficiency for pyruvate and alpha-ketoglutarate dehydrogenase."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
a boy who developed Leigh disease following a gastroenteritis and had
combined PDH and α-KGDH deficiency
explanation: >-
Index case with combined PDH and alpha-KGDH deficiency, causing lactic
acidosis.
- reference: PMID:29681092
reference_title: "LIPT1 deficiency presenting as early infantile epileptic encephalopathy, Leigh disease, and secondary pyruvate dehydrogenase complex deficiency."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
a 2-month-old male with severe lactic acidosis, refractory status
epilepticus, and brain imaging suggestive of Leigh disease
explanation: >-
Fifth case also presented with severe lactic acidosis, confirming this
as an obligate feature.
- name: Seizures
phenotype_term:
preferred_term: Seizure
term:
id: HP:0001250
label: Seizure
evidence:
- reference: PMID:29681092
reference_title: "LIPT1 deficiency presenting as early infantile epileptic encephalopathy, Leigh disease, and secondary pyruvate dehydrogenase complex deficiency."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
a 2-month-old male with severe lactic acidosis, refractory status
epilepticus, and brain imaging suggestive of Leigh disease
explanation: >-
Fifth case presented with refractory status epilepticus, and phenotype
progressed to early infantile epileptic encephalopathy.
- reference: PMID:29681092
reference_title: "LIPT1 deficiency presenting as early infantile epileptic encephalopathy, Leigh disease, and secondary pyruvate dehydrogenase complex deficiency."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
whose phenotype progressed to that of an early infantile epileptic
encephalopathy, which is novel compared to previously described patients
explanation: >-
Seizures can progress to epileptic encephalopathy, expanding the
phenotypic spectrum of LIPT1 deficiency.
- name: Abnormal muscle tone
phenotype_term:
preferred_term: Abnormal muscle tone
term:
id: HP:0003808
label: Abnormal muscle tone
evidence:
- reference: PMID:39199267
reference_title: "A Multi-Target Pharmacological Correction of a Lipoyltransferase LIPT1 Gene Mutation in Patient-Derived Cellular Models."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
early-onset seizures, psychomotor retardation, abnormal muscle tone,
severe lactic acidosis
explanation: >-
The abstract summarizes abnormal muscle tone as a reported feature of
LIPT1 deficiency.
- name: Global developmental delay
phenotype_term:
preferred_term: Global developmental delay
term:
id: HP:0001263
label: Global developmental delay
evidence:
- reference: PMID:29681092
reference_title: "LIPT1 deficiency presenting as early infantile epileptic encephalopathy, Leigh disease, and secondary pyruvate dehydrogenase complex deficiency."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
commonly presenting with severe lactic acidosis resulting in neonatal
death and/or poor neurocognitive outcomes
explanation: >-
Poor neurocognitive outcomes are a recognized consequence of LIPT1
deficiency across reported cases.
- reference: PMID:39199267
reference_title: "A Multi-Target Pharmacological Correction of a Lipoyltransferase LIPT1 Gene Mutation in Patient-Derived Cellular Models."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
early-onset seizures, psychomotor retardation, abnormal muscle tone,
severe lactic acidosis
explanation: >-
Psychomotor retardation supports the broader global developmental delay
phenotype mapping.
- name: Sideroblastic anemia
phenotype_term:
preferred_term: Sideroblastic anemia
term:
id: HP:0001924
label: Sideroblastic anemia
evidence:
- reference: PMID:39547509
reference_title: "Engineered bacterial lipoate protein ligase A (lplA) restores lipoylation in cell models of lipoylation deficiency."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
a patient with a homozygous c.212C>T variant LIPT1 with a previously
uncharacterized syndromic congenital sideroblastic anemia.
explanation: >-
Recent report expands the LIPT1 phenotype to include syndromic
congenital sideroblastic anemia.
biochemical:
- name: Lipoylated dehydrogenase E2 subunits
presence: DECREASED
context: >
LIPT1 deficiency reduces lipoylation of pyruvate dehydrogenase and
alpha-ketoglutarate dehydrogenase E2 subunits in patient-derived cells.
readouts:
- target: Defective lipoyl relay via LIPT1 deficiency
relationship: READOUT_OF
direction: NEGATIVE
endpoint_context: DIAGNOSTIC
interpretation: Reduced lipoylated dehydrogenase E2 subunits directly report the proximal LIPT1 lipoyl-transfer defect.
evidence:
- reference: PMID:39199267
reference_title: "A Multi-Target Pharmacological Correction of a Lipoyltransferase LIPT1 Gene Mutation in Patient-Derived Cellular Models."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
A Western blot analysis revealed a reduced expression of LIPT1 and
absent expression of lipoylated pyruvate dehydrogenase E2 (PDH E2) and
alpha-ketoglutarate dehydrogenase E2 (α-KGDH E2) subunits.
explanation: Patient-derived cellular models directly show absent lipoylated PDH E2 and alpha-KGDH E2 downstream of reduced LIPT1 expression.
evidence:
- reference: PMID:24256811
reference_title: "Mutations in the lipoyltransferase LIPT1 gene cause a fatal disease associated with a specific lipoylation defect of the 2-ketoacid dehydrogenase complexes."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
Immunostaining analysis showed that lipoylated E2-PDH and E2-KGDH
were extremely reduced in this patient.
explanation: >-
Patient fibroblast immunostaining directly supports decreased
lipoylated dehydrogenase E2 subunits.
- reference: PMID:39199267
reference_title: "A Multi-Target Pharmacological Correction of a Lipoyltransferase LIPT1 Gene Mutation in Patient-Derived Cellular Models."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
A Western blot analysis revealed a reduced expression of LIPT1 and
absent expression of lipoylated pyruvate dehydrogenase E2 (PDH E2) and
alpha-ketoglutarate dehydrogenase E2 (α-KGDH E2) subunits.
explanation: >-
Western blot evidence from patient-derived cellular models confirms
absent lipoylated PDH E2 and alpha-KGDH E2.
- name: Pyruvate and alpha-ketoglutarate dehydrogenase activity
presence: DECREASED
context: >
Reduced lipoylation lowers PDH and alpha-KGDH enzymatic activity, limiting
pyruvate entry into the TCA cycle and TCA-cycle flux.
readouts:
- target: Combined alpha-ketoacid dehydrogenase deficiency with spared glycine cleavage
relationship: READOUT_OF
direction: NEGATIVE
endpoint_context: DIAGNOSTIC
interpretation: Reduced PDH and alpha-KGDH activity reports the combined alpha-ketoacid dehydrogenase-deficiency branch.
evidence:
- reference: PMID:39199267
reference_title: "A Multi-Target Pharmacological Correction of a Lipoyltransferase LIPT1 Gene Mutation in Patient-Derived Cellular Models."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
Accordingly, activities of PDH and α-KGDH were markedly reduced,
associated with cell bioenergetics failure, iron accumulation, and
lipid peroxidation.
explanation: Patient-derived cellular models directly document reduced PDH and alpha-KGDH activities.
evidence:
- reference: PMID:39199267
reference_title: "A Multi-Target Pharmacological Correction of a Lipoyltransferase LIPT1 Gene Mutation in Patient-Derived Cellular Models."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
Accordingly, activities of PDH and α-KGDH were markedly reduced,
associated with cell bioenergetics failure, iron accumulation, and lipid
peroxidation.
explanation: >-
The cellular model directly documents reduced PDH and alpha-KGDH
activities.
- name: Glycine
presence: NORMAL
context: >
Glycine elevation is absent because GCSH lipoylation and glycine cleavage
remain intact, distinguishing LIPT1 deficiency from LIAS and LIPT2
deficiency.
readouts:
- target: Combined alpha-ketoacid dehydrogenase deficiency with spared glycine cleavage
relationship: READOUT_OF
direction: PRESENT_ABSENT
endpoint_context: DIAGNOSTIC
interpretation: Normal glycine reports the spared glycine-cleavage component that distinguishes LIPT1 deficiency from upstream lipoate biosynthesis defects.
evidence:
- reference: PMID:24256811
reference_title: "Mutations in the lipoyltransferase LIPT1 gene cause a fatal disease associated with a specific lipoylation defect of the 2-ketoacid dehydrogenase complexes."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
However, the absence of glycine elevation, the normal activity of the
glycine cleavage system and the normal lipoylation of the H protein
suggested a defect of lipoic acid transfer to particular proteins rather
than a general impairment of lipoic acid biosynthesis
explanation: Patient biochemical testing supports normal glycine as the readout of preserved glycine cleavage in LIPT1 deficiency.
evidence:
- reference: PMID:24256811
reference_title: "Mutations in the lipoyltransferase LIPT1 gene cause a fatal disease associated with a specific lipoylation defect of the 2-ketoacid dehydrogenase complexes."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
However, the absence of glycine elevation, the normal activity of the
glycine cleavage system and the normal lipoylation of the H protein
suggested a defect of lipoic acid transfer to particular proteins rather
than a general impairment of lipoic acid biosynthesis
explanation: >-
Patient biochemical testing supports normal glycine levels and preserved
glycine cleavage in LIPT1 deficiency.
- name: Increased urine lactate, ketoglutarate, and 2-oxoacid levels
presence: INCREASED
context: >
Urinary lactate, ketoglutarate, and 2-oxoacid accumulation reflects the
downstream metabolic block from deficient 2-ketoacid dehydrogenase activity.
readouts:
- target: Combined alpha-ketoacid dehydrogenase deficiency with spared glycine cleavage
relationship: READOUT_OF
direction: POSITIVE
endpoint_context: DIAGNOSTIC
interpretation: Increased urine lactate, ketoglutarate, and 2-oxoacids report the downstream metabolite accumulation caused by combined dehydrogenase deficiency.
evidence:
- reference: PMID:39199267
reference_title: "A Multi-Target Pharmacological Correction of a Lipoyltransferase LIPT1 Gene Mutation in Patient-Derived Cellular Models."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
increased urine lactate, ketoglutarate, and 2-oxoacid levels.
explanation: The clinical summary directly identifies this urinary metabolite pattern in LIPT1 deficiency.
evidence:
- reference: PMID:39199267
reference_title: "A Multi-Target Pharmacological Correction of a Lipoyltransferase LIPT1 Gene Mutation in Patient-Derived Cellular Models."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
increased urine lactate, ketoglutarate, and 2-oxoacid levels.
explanation: >-
The clinical summary in the abstract lists increased urinary lactate,
ketoglutarate, and 2-oxoacid levels in LIPT1 deficiency.
genetic:
- name: LIPT1 loss-of-function variants
association: Causative
relationship_type: CAUSATIVE
gene_term:
preferred_term: LIPT1
term:
id: hgnc:29569
label: LIPT1
variant_origin: GERMLINE
notes: >
Biallelic loss-of-function mutations in LIPT1 cause lipoyl transferase 1
deficiency. Both compound heterozygous and homozygous mutations have been
reported. First described by Soreze et al. 2013 and Tort et al. 2014.
evidence:
- reference: PMID:24341803
reference_title: "Mutations in human lipoyltransferase gene LIPT1 cause a Leigh disease with secondary deficiency for pyruvate and alpha-ketoglutarate dehydrogenase."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Exome sequencing identified two heterozygous mutations (c.875C > G and
c.535A > G) in the LIPT1 gene that encodes a mitochondrial
lipoyltransferase which is thought to catalyze the attachment of lipoic
acid on PDHc, α-KGDHc, and BCKDHc
explanation: >-
First identification of pathogenic LIPT1 variants, establishing
causality for Leigh disease with secondary PDH and alpha-KGDH
deficiency.
- reference: PMID:24341803
reference_title: "Mutations in human lipoyltransferase gene LIPT1 cause a Leigh disease with secondary deficiency for pyruvate and alpha-ketoglutarate dehydrogenase."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
cDNA transfection experiments on patient fibroblasts rescued PDH and
α-KGDH activities and normalized the levels of pyruvate and
3OHbutyrate in cell supernatants
explanation: >-
Functional complementation with wild-type LIPT1 cDNA rescued enzyme
activities, proving that the variants are disease-causing.
- reference: PMID:24256811
reference_title: "Mutations in the lipoyltransferase LIPT1 gene cause a fatal disease associated with a specific lipoylation defect of the 2-ketoacid dehydrogenase complexes."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
Functional complementation experiments in patient's fibroblasts
demonstrated that these mutations are disease-causing and that LIPT1
protein is required for lipoylation and activation of 2-ketoacid
dehydrogenases in humans
explanation: >-
Independent functional validation in a second patient confirming LIPT1
mutations as disease-causing.
- reference: PMID:29681092
reference_title: "LIPT1 deficiency presenting as early infantile epileptic encephalopathy, Leigh disease, and secondary pyruvate dehydrogenase complex deficiency."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
We describe the fifth case of LIPT1 deficiency, whose phenotype
progressed to that of an early infantile epileptic encephalopathy
explanation: >-
Fifth case expanding the genetic and phenotypic spectrum of LIPT1
deficiency.
- reference: PMID:29681092
reference_title: "LIPT1 deficiency presenting as early infantile epileptic encephalopathy, Leigh disease, and secondary pyruvate dehydrogenase complex deficiency."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
they are and have been presumptively under-diagnosed without exome
sequencing
explanation: >-
LIPT1 deficiency is likely under-diagnosed due to biochemical and
phenotypic overlap with PDH deficiency and nonketotic
hyperglycinemia.
- reference: PMID:39547509
reference_title: "Engineered bacterial lipoate protein ligase A (lplA) restores lipoylation in cell models of lipoylation deficiency."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
a patient with a homozygous c.212C>T variant LIPT1 with a previously
uncharacterized syndromic congenital sideroblastic anemia
explanation: >-
Additional reported patient with a homozygous LIPT1 variant, expanding the
phenotypic spectrum to include congenital sideroblastic anemia.
treatments:
- name: Lipoic acid supplementation (limited evidence)
description: >
Lipoic acid supplementation has been tested in yeast models and patient
fibroblasts, with limited biochemical improvement and review-level evidence
arguing against established clinical benefit.
treatment_term:
preferred_term: Pharmacotherapy
term:
id: NCIT:C15986
label: Pharmacotherapy
therapeutic_agent:
- preferred_term: alpha-lipoic acid
term:
id: CHEBI:16494
label: lipoic acid
target_mechanisms:
- target: Combined alpha-ketoacid dehydrogenase deficiency with spared glycine cleavage
treatment_effect: MODULATES
description: >-
Lipoic acid supplementation may partially modulate downstream lactate
readouts in models, but it has not been established as clinically
effective for LIPT1 deficiency.
evidence:
- reference: PMID:24341803
reference_title: "Mutations in human lipoyltransferase gene LIPT1 cause a Leigh disease with secondary deficiency for pyruvate and alpha-ketoglutarate dehydrogenase."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
The yeast lip3 deletion strain showed improved growth on ethanol
medium after lipoic acid supplementation
explanation: >-
Lipoic acid supplementation partially rescued the yeast model
(lip3 deletion strain), suggesting a possible but limited therapeutic
avenue.
- reference: PMID:24341803
reference_title: "Mutations in human lipoyltransferase gene LIPT1 cause a Leigh disease with secondary deficiency for pyruvate and alpha-ketoglutarate dehydrogenase."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
incubation of the patient fibroblasts with lipoic acid decreased
lactate level in cell supernatants
explanation: >-
Lipoic acid supplementation modestly improved lactate levels in patient
fibroblasts, though clinical benefit remains unproven.
- reference: PMID:32508887
reference_title: "Progress in the Enzymology of the Mitochondrial Diseases of Lipoic Acid Requiring Enzymes."
supports: REFUTE
evidence_source: OTHER
snippet: >-
lipoic acid supplementation of the diets of human LIAS, LIPT1, and
LIPT2 patients or of their fibroblast cultures failed to alleviate the
physiological and biochemical effects of the mutant genes
explanation: >-
Review concludes that lipoic acid supplementation has not been
effective in alleviating the effects of lipoylation pathway mutations
in patients.
- name: Multi-target pharmacological cocktail (experimental)
description: >
An experimental multi-target pharmacological approach using pantothenate,
nicotinamide, vitamin E, thiamine, biotin, and alpha-lipoic acid has
shown promise in LIPT1-deficient patient-derived cellular models. The
cocktail restored LIPT1 expression, lipoylation of
mitochondrial proteins, and cellular bioenergetics while eliminating iron
overload and lipid peroxidation. The mechanism appears mediated through
SIRT3 activation. This has not yet been tested in patients.
treatment_term:
preferred_term: Pharmacotherapy
term:
id: NCIT:C15986
label: Pharmacotherapy
therapeutic_agent:
- preferred_term: pantothenate
term:
id: CHEBI:16454
label: pantothenate
- preferred_term: nicotinamide
term:
id: CHEBI:17154
label: nicotinamide
- preferred_term: vitamin E
term:
id: CHEBI:33234
label: vitamin E
- preferred_term: thiamine
term:
id: CHEBI:26948
label: vitamin B1
- preferred_term: biotin
term:
id: CHEBI:15956
label: biotin
- preferred_term: alpha-lipoic acid
term:
id: CHEBI:16494
label: lipoic acid
target_mechanisms:
- target: Defective lipoyl relay via LIPT1 deficiency
treatment_effect: RESTORES
description: >-
The cocktail increased LIPT1 expression and lipoylation of mitochondrial
proteins in patient-derived cellular models.
evidence:
- reference: PMID:39199267
reference_title: "A Multi-Target Pharmacological Correction of a Lipoyltransferase LIPT1 Gene Mutation in Patient-Derived Cellular Models."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
a cocktail of antioxidants and mitochondrial boosting agents consisting
of pantothenate, nicotinamide, vitamin E, thiamine, biotin, and
α-lipoic acid, which is capable of rescuing LIPT1 pathophysiology,
increasing the LIPT1 expression and lipoylation of mitochondrial
proteins, improving cell bioenergetics, and eliminating iron overload
and lipid peroxidation
explanation: >-
The treatment directly improved LIPT1 expression and mitochondrial
protein lipoylation in the cellular model.
- target: Mitochondrial bioenergetic failure and lipid peroxidation
treatment_effect: RESTORES
description: >-
The same cocktail improved cellular bioenergetics and eliminated iron
overload and lipid peroxidation.
evidence:
- reference: PMID:39199267
reference_title: "A Multi-Target Pharmacological Correction of a Lipoyltransferase LIPT1 Gene Mutation in Patient-Derived Cellular Models."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
a cocktail of antioxidants and mitochondrial boosting agents consisting
of pantothenate, nicotinamide, vitamin E, thiamine, biotin, and
α-lipoic acid, which is capable of rescuing LIPT1 pathophysiology,
increasing the LIPT1 expression and lipoylation of mitochondrial
proteins, improving cell bioenergetics, and eliminating iron overload
and lipid peroxidation
explanation: >-
The treatment target matches the reported rescue of bioenergetics,
iron accumulation, and lipid peroxidation.
evidence:
- reference: PMID:39199267
reference_title: "A Multi-Target Pharmacological Correction of a Lipoyltransferase LIPT1 Gene Mutation in Patient-Derived Cellular Models."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
a cocktail of antioxidants and mitochondrial boosting agents consisting
of pantothenate, nicotinamide, vitamin E, thiamine, biotin, and
α-lipoic acid, which is capable of rescuing LIPT1 pathophysiology,
increasing the LIPT1 expression and lipoylation of mitochondrial
proteins, improving cell bioenergetics, and eliminating iron overload
and lipid peroxidation
explanation: >-
Gómez-Fernández et al. identified a multi-agent cocktail that rescued
LIPT1 pathophysiology in patient-derived cellular models, representing
the first targeted pharmacological approach for this disorder.
datasets:
references:
- reference: DOI:10.1016/j.jbc.2023.105046
title: FDX1 regulates cellular protein lipoylation through direct binding to LIAS
findings: []
- reference: DOI:10.1016/j.jbc.2024.107995
title: Engineered bacterial lipoate protein ligase A (lplA) restores lipoylation in cell models of lipoylation deficiency
findings: []
- reference: DOI:10.1177/1073858420936162
title: Mitochondrial Fatty Acids and Neurodegenerative Disorders
findings: []
Disease Pathophysiology Research Report
Target Disease - Disease Name: Lipoyl Transferase 1 Deficiency (LIPT1 deficiency) - MONDO ID: not reliably identified in the accessible sources; LIPT1 deficiency is recognized among human disorders of mitochondrial protein lipoylation. - Category: Mendelian
1) Core Pathophysiology - Primary mechanistic defect: loss or reduction of mitochondrial protein lipoylation on the E2 subunits (dihydrolipoyl acyltransferases) of four multienzyme complexes: pyruvate dehydrogenase (PDH; E2=DLAT), α-ketoglutarate dehydrogenase/OGDH (E2=DLST), branched-chain α‑ketoacid dehydrogenase/BCKDH (E2=DBT), and glycine cleavage system (GCS; H protein=GCSH). Disruption of lipoylation leads to loss of activity of these complexes and impaired cellular respiration with glucose-dependence phenotypes (e.g., growth failure in low glucose) (URL: https://doi.org/10.1016/j.jbc.2023.105046; https://doi.org/10.1016/j.jbc.2024.107995) (dreishpoon2023fdx1regulatescellular pages 1-2, bick2024engineeredbacteriallipoate pages 2-3, bick2024engineeredbacteriallipoate pages 4-5). - Lipoylation pathway steps: mitochondrial fatty acid synthesis (mtFAS) generates octanoyl-ACP; LIPT2 transfers octanoyl to GCSH; LIAS (radical SAM enzyme, Fe–S cluster dependent, supported by FDX1) inserts sulfur atoms to generate lipoyl-GCSH; LIPT1 transfers the lipoyl moiety from GCSH to E2 lysine residues on PDH/OGDH/BCKDH and to the H protein as needed. This establishes the linear dependency mtFAS → LIPT2 → LIAS (with FDX1/Fe–S support) → LIPT1 → lipoylated PDH/OGDH/BCKDH/GCS (URLs: https://doi.org/10.1016/j.jbc.2023.105046; https://doi.org/10.1177/1073858420936162) (dreishpoon2023fdx1regulatescellular pages 1-2, kastaniotis2021mitochondrialfattyacids pages 42-47). - Cellular processes affected: loss of lipoylation impairs mitochondrial oxidative metabolism, leading to decreased cellular respiration, activation of integrated stress responses, and heightened sensitivity to glucose limitation (URL: https://doi.org/10.1016/j.jbc.2023.105046). Experimental rescue of lipoylation restores basal respiration and proliferation in low glucose (URL: https://doi.org/10.1016/j.jbc.2024.107995) (dreishpoon2023fdx1regulatescellular pages 1-2, bick2024engineeredbacteriallipoate pages 2-3). - Metabolic consequences: reduced PDH activity promotes pyruvate accumulation and lactic acidosis; reduced OGDH impairs TCA cycle flux (α‑ketoglutarate utilization); reduced BCKDH causes branched‑chain α‑ketoacid accumulation; reduced GCS activity can elevate glycine in some lipoylation disorders. Reviews and case reports link LIPT1 defects to lethal lactic acidosis and Leigh‑like presentations (URL: https://doi.org/10.1177/1073858420936162) (kastaniotis2021mitochondrialfattyacids pages 32-37, kastaniotis2021mitochondrialfattyacids pages 42-47, kastaniotis2021mitochondrialfattyacids pages 37-42). - Relationship to copper toxicity (cuproptosis): Lipoylation is central to the copper‑dependent cytotoxic program; upstream regulation by FDX1–LIAS modulates protein lipoylation that participates in copper‑induced cell death signaling. While not a clinical feature of LIPT1 deficiency per se, this mechanistic axis underscores how defective lipoylation alters susceptibility to copper‑linked stress (URL: https://doi.org/10.1016/j.jbc.2023.105046) (dreishpoon2023fdx1regulatescellular pages 1-2).
2) Key Molecular Players - Genes/Proteins (HGNC): - LIPT1 (Lipoyltransferase 1): transfers lipoyl moiety from GCSH to E2 subunits (PDH/OGDH/BCKDH) and maintains lipoylation of the glycine cleavage H‑protein (URLs: https://doi.org/10.1016/j.jbc.2024.107995; https://doi.org/10.1177/1073858420936162) (bick2024engineeredbacteriallipoate pages 4-5, kastaniotis2021mitochondrialfattyacids pages 42-47). - LIPT2: octanoyl transfer to GCSH upstream of LIAS (URL: https://doi.org/10.1016/j.jbc.2023.105046) (dreishpoon2023fdx1regulatescellular pages 1-2). - LIAS: lipoic acid synthase; inserts sulfur into octanoyl-GCSH; requires Fe–S and is supported by FDX1 (URL: https://doi.org/10.1016/j.jbc.2023.105046) (dreishpoon2023fdx1regulatescellular pages 1-2). - FDX1: directly binds LIAS to promote cellular protein lipoylation (URL: https://doi.org/10.1016/j.jbc.2023.105046) (dreishpoon2023fdx1regulatescellular pages 1-2). - Upstream mtFAS components (e.g., MECR, ACP/NDUFAB1): provide octanoyl-ACP precursor; deficiency reduces global mitochondrial lipoylation and can impair respiratory complex integrity (URL: https://doi.org/10.1177/1073858420936162) (kastaniotis2021mitochondrialfattyacids pages 42-47). - Chemical entities (CHEBI): lipoic acid (cofactor); pyruvate; lactate; α‑ketoglutarate; branched‑chain α‑ketoacids (mechanistic relevance inferred via affected complexes) (kastaniotis2021mitochondrialfattyacids pages 32-37, kastaniotis2021mitochondrialfattyacids pages 42-47). - Cell types (CL): neurons and astrocytes (high oxidative demand); myocytes; hepatocytes—tissues with high mitochondrial flux are vulnerable when lipoylation is impaired (review synthesis) (kastaniotis2021mitochondrialfattyacids pages 32-37, kastaniotis2021mitochondrialfattyacids pages 42-47). - Anatomical locations (UBERON): central nervous system (brain), skeletal muscle, liver, and heart are commonly implicated in mitochondrial energy failure syndromes and are consistent with reported clinical features in LIPT1 deficiency (review synthesis) (kastaniotis2021mitochondrialfattyacids pages 32-37, kastaniotis2021mitochondrialfattyacids pages 42-47).
3) Biological Processes (GO) Disrupted - Protein lipoylation; lipoate biosynthetic process; mitochondrial acetyl‑CoA metabolism; pyruvate dehydrogenase complex cycle; tricarboxylic acid (TCA) cycle; branched‑chain amino acid catabolic process; glycine catabolic process; mitochondrial respiratory chain function and cellular respiration (URLs: https://doi.org/10.1016/j.jbc.2023.105046; https://doi.org/10.1177/1073858420936162; https://doi.org/10.1016/j.jbc.2024.107995) (dreishpoon2023fdx1regulatescellular pages 1-2, kastaniotis2021mitochondrialfattyacids pages 42-47, bick2024engineeredbacteriallipoate pages 2-3).
4) Cellular Components - Mitochondrial matrix (site of PDH/OGDH/BCKDH/GCS and lipoylation reactions); inner mitochondrial membrane/respiratory chain complexes affected secondarily; lipoyl moieties attached to E2 subunits (DLAT, DLST) and GCSH (URLs: https://doi.org/10.1016/j.jbc.2023.105046; https://doi.org/10.1177/1073858420936162; https://doi.org/10.1016/j.jbc.2024.107995) (dreishpoon2023fdx1regulatescellular pages 1-2, kastaniotis2021mitochondrialfattyacids pages 42-47, bick2024engineeredbacteriallipoate pages 2-3).
5) Disease Progression (Mechanistic Sequence) - Initiation: biallelic pathogenic variants in LIPT1 reduce or abolish transfer of lipoyl groups to E2 subunits/H‑protein. - Molecular consequences: reduction/absence of lipoylated DLAT/DLST (and likely DBT/GCSH), causing loss of PDH/OGDH/BCKDH/GCS activity and impaired TCA cycle entry and flux (URLs: https://doi.org/10.1016/j.jbc.2024.107995; https://doi.org/10.1177/1073858420936162) (bick2024engineeredbacteriallipoate pages 4-5, kastaniotis2021mitochondrialfattyacids pages 42-47). - Cellular outcomes: decreased mitochondrial respiration, increased reliance on glycolysis, stress‑response activation, and vulnerability to low‑glucose environments (URL: https://doi.org/10.1016/j.jbc.2023.105046) (dreishpoon2023fdx1regulatescellular pages 1-2). - Metabolic derangements: pyruvate accumulation and lactic acidosis; α‑ketoglutarate utilization block; branched‑chain α‑ketoacid accumulation; potential glycine elevation depending on GCS involvement (review/case synthesis) (kastaniotis2021mitochondrialfattyacids pages 32-37, kastaniotis2021mitochondrialfattyacids pages 42-47, kastaniotis2021mitochondrialfattyacids pages 37-42). - Clinical manifestation: neonatal/infantile onset lactic acidosis; encephalopathy with Leigh‑like features; hypotonia/spasticity; developmental delay; neuroimaging abnormalities (cortical/cerebellar atrophy, white‑matter changes); occasionally systemic features (e.g., congenital sideroblastic anemia reported in one LIPT1‑mutant individual) (URLs: https://doi.org/10.1016/j.jbc.2024.107995; https://doi.org/10.1177/1073858420936162) (bick2024engineeredbacteriallipoate pages 5-6, kastaniotis2021mitochondrialfattyacids pages 37-42).
6) Phenotypic Manifestations (with HP term mapping and links to mechanism) - Lactic acidosis (HP:0003128): due to reduced PDH activity and impaired entry of pyruvate into the TCA cycle (URL: https://doi.org/10.1177/1073858420936162) (kastaniotis2021mitochondrialfattyacids pages 32-37, kastaniotis2021mitochondrialfattyacids pages 37-42). - Developmental delay (HP:0001263) and encephalopathy/Leigh‑like features (HP:0006805/HP:0007340): from global mitochondrial energy failure in CNS (URLs: https://doi.org/10.1177/1073858420936162) (kastaniotis2021mitochondrialfattyacids pages 32-37, kastaniotis2021mitochondrialfattyacids pages 42-47). - Hypotonia (HP:0001252) and/or spasticity (HP:0001257): neuro‑motor pathway involvement and energy failure (URL: https://doi.org/10.1016/j.jbc.2024.107995) (bick2024engineeredbacteriallipoate pages 5-6). - Microcephaly (HP:0000252), cortical/cerebellar atrophy (HP:0001272/HP:0001272—cerebellar atrophy), and white‑matter abnormalities (HP:0007340): neuroimaging findings reported across lipoylation‑defect series including LIPT1 (URL: https://doi.org/10.1016/j.jbc.2024.107995) (bick2024engineeredbacteriallipoate pages 5-6). - Possible elevated glycine (HP:0002150) when GCS is hypolipoylated (supported broadly across lipoylation defects) (kastaniotis2021mitochondrialfattyacids pages 32-37, kastaniotis2021mitochondrialfattyacids pages 42-47). - Congenital sideroblastic anemia (HP:0004810) as an atypical presentation in a homozygous LIPT1 (p.Ser71Phe) individual (URL: https://doi.org/10.1016/j.jbc.2024.107995) (bick2024engineeredbacteriallipoate pages 4-5, bick2024engineeredbacteriallipoate pages 5-6).
7) Expert Opinions and Analysis (from authoritative sources) - Mechanistic centrality of FDX1–LIAS: Direct binding between FDX1 and LIAS establishes FDX1 as an upstream regulator of mitochondrial protein lipoylation, separating the phenotype from general Fe–S biogenesis and clarifying the control node upstream of LIPT1 (URL: https://doi.org/10.1016/j.jbc.2023.105046) (dreishpoon2023fdx1regulatescellular pages 1-2). - Pathway integration of mtFAS and lipoylation: The foundational review emphasizes that mtFAS supplies octanoyl‑ACP for lipoic acid synthesis and that deficits in mtFAS/lipoylation factors (LIAS, LIPT1, LIPT2) lead to multi‑system energy failure, especially in the CNS; it documents lethal lactic acidosis and Leigh‑like disease with LIPT1 defects (URL: https://doi.org/10.1177/1073858420936162) (kastaniotis2021mitochondrialfattyacids pages 32-37, kastaniotis2021mitochondrialfattyacids pages 42-47, kastaniotis2021mitochondrialfattyacids pages 37-42). - Therapeutic concept and proof‑of‑principle: A mitochondrially targeted bacterial lipoate protein ligase (lplA) with exogenous lipoic acid can bypass defective human lipoylation biosynthesis and restore lipoylation and respiration in cell models, suggesting a potential route to therapy development (URL: https://doi.org/10.1016/j.jbc.2024.107995) (bick2024engineeredbacteriallipoate pages 2-3, bick2024engineeredbacteriallipoate pages 4-5).
8) Relevant Statistics and Data (recent studies) - Cellular phenotypes: In human cell models lacking lipoylation (including LIPT1‑mutant cells), basal respiration and proliferation in low glucose are impaired and can be restored by engineered lplA plus lipoic acid (URL: https://doi.org/10.1016/j.jbc.2024.107995) (bick2024engineeredbacteriallipoate pages 2-3). - Clinical data: Case‑level descriptions note lactic acidosis and severe neurodevelopmental phenotypes in LIPT1 deficiency, including reports of fatal neonatal disease; however, aggregated cohort statistics (e.g., prevalence, survival curves) are not available in the accessible sources cited here (URL: https://doi.org/10.1177/1073858420936162; https://doi.org/10.1016/j.jbc.2024.107995) (kastaniotis2021mitochondrialfattyacids pages 37-42, bick2024engineeredbacteriallipoate pages 5-6).
Embedded Evidence Table | Source (first author, year, journal) | URL / DOI | Publication date | Key mechanistic findings | Enzymes / complexes affected (PDH/DLAT, OGDH/DLST, BCKDH/DBT, GCS/GCSH) | Pathway context | Clinical / phenotype notes | Context ID to cite | |---|---|---:|---|---|---|---|---| | Bick 2024, Journal of Biological Chemistry | https://doi.org/10.1016/j.jbc.2024.107995 | Dec 2024 | Engineered mitochondrial bacterial lplA plus lipoic acid restores protein lipoylation, rescues basal respiration and low‑glucose growth in lipoylation‑deficient cell models; documents a homozygous LIPT1 (c.212C>T, p.Ser71Phe) with reduced lipoylated DLAT/DLST. | PDH / DLAT (explicit); OGDH / DLST (explicit); BCKDH / DBT (not explicit; canonical targets stated); GCS / GCSH (not explicit; canonical targets stated) | mtFAS → LIPT2 → LIAS → LIPT1; LIAS/Fe–S and FDX1 implicated upstream; MLS‑lplA can bypass defective transfer | • Reported patient phenotypes across series: lactic acidosis, developmental delay, hypotonia, spasticity, cortical/cerebellar atrophy; one case with congenital sideroblastic anemia | (bick2024engineeredbacteriallipoate pages 4-5) | | Dreishpoon 2023, Journal of Biological Chemistry | https://doi.org/10.1016/j.jbc.2023.105046 | Sep 2023 | FDX1 directly binds LIAS and promotes cellular protein lipoylation; FDX1 loss impairs lipoylation‑dependent enzymes causing loss of respiration, integrated stress response, and glucose‑sensitivity; links lipoylation defects to copper‑related toxicity mechanisms. | PDH / DLAT (explicit); OGDH / DLST (explicit); BCKDH / DBT (explicit); GCS / GCSH (explicit) | mtFAS → LIPT2 → LIAS (FDX1 supports LIAS) → LIPT1; emphasizes Fe–S/FDX1 involvement in LIAS activity | • Cellular phenotypes: loss of respiration, sensitivity to mild glucose starvation, induction of stress response | (dreishpoon2023fdx1regulatescellular pages 1-2) | | Kastaniotis 2021, The Neuroscientist (foundational review) | https://doi.org/10.1177/1073858420936162 | Jul 2021 | mtFAS supplies octanoyl‑ACP precursor for lipoic acid synthesis; mutations in LIPT1 cause a specific lipoylation defect of 2‑ketoacid dehydrogenase complexes leading to mitochondrial energy failure and reported lethal lactic acidosis in cases. | PDH / DLAT (explicit); OGDH / DLST (explicit); BCKDH / DBT (explicit); GCS / GCSH (explicit/inferred) | mtFAS → LIPT2 → LIAS → LIPT1; highlights requirement of Fe–S–dependent LIAS and coordination with Fe–S cluster biogenesis | • Clinical associations: Leigh‑like presentations, fatal neonatal lactic acidosis, dystonia, hypotonia/hypertonia, delayed psychomotor development | (kastaniotis2021mitochondrialfattyacids pages 32-37) |
Table: Concise evidence table summarizing key mechanistic findings, affected enzyme complexes, pathway context, and clinical notes from three primary/foundational sources on LIPT1 deficiency for rapid reference and knowledge‑base annotation.
Structured Annotations for Knowledge Base - Genes/Proteins (HGNC): LIPT1; LIPT2; LIAS; FDX1; DLAT (PDH E2); DLST (OGDH E2); DBT (BCKDH E2); GCSH (GCS H-protein) (dreishpoon2023fdx1regulatescellular pages 1-2, kastaniotis2021mitochondrialfattyacids pages 42-47, bick2024engineeredbacteriallipoate pages 4-5). - Biological Process (GO-like terms): protein lipoylation; lipoate biosynthetic process; tricarboxylic acid cycle; pyruvate dehydrogenase complex activity; branched‑chain amino acid catabolic process; glycine catabolic process; mitochondrial respiratory chain and cellular respiration (dreishpoon2023fdx1regulatescellular pages 1-2, kastaniotis2021mitochondrialfattyacids pages 42-47). - Cellular Component: mitochondrial matrix; inner mitochondrial membrane/respiratory chain complexes; PDH/OGDH/BCKDH/GCS holoenzymes (dreishpoon2023fdx1regulatescellular pages 1-2, kastaniotis2021mitochondrialfattyacids pages 42-47). - Phenotypes (HP): lactic acidosis (HP:0003128); developmental delay (HP:0001263); hypotonia (HP:0001252); spasticity (HP:0001257); encephalopathy/Leigh‑like features (HP:0006805/HP:0007340); microcephaly (HP:0000252); cortical/cerebellar atrophy (HP:0001272); white‑matter abnormalities (HP:0007340); congenital sideroblastic anemia (HP:0004810) (bick2024engineeredbacteriallipoate pages 5-6, kastaniotis2021mitochondrialfattyacids pages 37-42, kastaniotis2021mitochondrialfattyacids pages 32-37). - Cell Types (CL): neurons (CL:0000540) and glia; skeletal myocytes (CL:0000187); hepatocytes (CL:0000182) – high energy‑demand tissues implicated in mitochondrial lipoylation defects (kastaniotis2021mitochondrialfattyacids pages 32-37, kastaniotis2021mitochondrialfattyacids pages 42-47). - Anatomical Locations (UBERON): brain (UBERON:0000955); skeletal muscle (UBERON:0002385); liver (UBERON:0002107); heart (UBERON:0000948) (kastaniotis2021mitochondrialfattyacids pages 32-37, kastaniotis2021mitochondrialfattyacids pages 42-47). - Chemical entities (CHEBI): lipoic acid (CHEBI:16497); pyruvate (CHEBI:15361); lactate (CHEBI:16651); α‑ketoglutarate (CHEBI:16810); branched‑chain α‑ketoacids (class) (kastaniotis2021mitochondrialfattyacids pages 32-37, kastaniotis2021mitochondrialfattyacids pages 42-47).
Selected Evidence Quotes (verbatim where available) - “FDX1 regulates protein lipoylation by directly binding to the lipoyl synthase (LIAS) enzyme… [and] the predominant cellular metabolic outcome of FDX1 loss-of-function is manifested through the regulation of the four lipoylation-dependent enzymes ultimately resulting in loss of cellular respiration and sensitivity to mild glucose starvation.” URL: https://doi.org/10.1016/j.jbc.2023.105046 (dreishpoon2023fdx1regulatescellular pages 1-2). - “Engineered mitochondrial lplA plus lipoic acid… restored protein lipoylation and growth in low glucose… including restoration of lipoylated DLAT and DLST” (paraphrase of results detailed in Bick 2024 JBC). URL: https://doi.org/10.1016/j.jbc.2024.107995 (bick2024engineeredbacteriallipoate pages 2-3, bick2024engineeredbacteriallipoate pages 4-5). - “Mutations in the lipoyltransferase LIPT1 gene cause a fatal disease associated with a specific lipoylation defect of the 2‑ketoacid dehydrogenase complexes.” (as summarized in the review’s cited case literature). URL: https://doi.org/10.1177/1073858420936162 (kastaniotis2021mitochondrialfattyacids pages 37-42).
Recent Developments and Applications (2023–2024 Priority) - FDX1–LIAS mechanistic clarification (2023): establishes a direct regulatory interaction controlling mitochondrial protein lipoylation and cellular respiration under glucose limitation; strengthens upstream context for LIPT1‑dependent lipoylation (URL: https://doi.org/10.1016/j.jbc.2023.105046) (dreishpoon2023fdx1regulatescellular pages 1-2). - Therapeutic concept testing (2024): mitochondrially targeted bacterial lplA plus lipoic acid supplementation rescues lipoylation and respiration in human cell models with lipoylation defects, including LIPT1‑mutant cells, suggesting a tractable therapeutic strategy to bypass endogenous biosynthesis (URL: https://doi.org/10.1016/j.jbc.2024.107995) (bick2024engineeredbacteriallipoate pages 2-3, bick2024engineeredbacteriallipoate pages 4-5).
URLs and Publication Dates - Dreishpoon MB et al., J Biol Chem. Published Sep 2023. URL: https://doi.org/10.1016/j.jbc.2023.105046 (dreishpoon2023fdx1regulatescellular pages 1-2). - Bick NR et al., J Biol Chem. Published Dec 2024. URL: https://doi.org/10.1016/j.jbc.2024.107995 (bick2024engineeredbacteriallipoate pages 4-5, bick2024engineeredbacteriallipoate pages 2-3). - Kastaniotis AJ et al., The Neuroscientist. Published Jul 2021. URL: https://doi.org/10.1177/1073858420936162 (kastaniotis2021mitochondrialfattyacids pages 32-37, kastaniotis2021mitochondrialfattyacids pages 42-47, kastaniotis2021mitochondrialfattyacids pages 37-42).
Limitations and Gaps - Aggregated clinical statistics (e.g., number of reported families, genotype–phenotype stratification, survival estimates) were not available in the accessible excerpts. The mechanistic picture is strong and consistent, but epidemiology remains to be consolidated from broader clinical genetics literature (bick2024engineeredbacteriallipoate pages 5-6, kastaniotis2021mitochondrialfattyacids pages 37-42).
Conclusion LIPT1 deficiency is a disorder of mitochondrial protein lipoylation in which failure to transfer the lipoyl cofactor to E2/H‑protein substrates disables PDH, OGDH, BCKDH, and GCS, producing systemic energy failure with hallmark lactic acidosis and neurodevelopmental phenotypes. Upstream mtFAS, LIPT2, and LIAS (supported by FDX1 and Fe–S biogenesis) define a linear pathway culminating in LIPT1‑dependent lipoylation. Recent advances clarify upstream control (FDX1–LIAS) and demonstrate a therapeutic bypass (mitochondrial lplA + lipoic acid) restoring lipoylation and respiration in human cell models, underscoring translational potential (dreishpoon2023fdx1regulatescellular pages 1-2, kastaniotis2021mitochondrialfattyacids pages 42-47, bick2024engineeredbacteriallipoate pages 2-3, bick2024engineeredbacteriallipoate pages 4-5).
References
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