NM_004328.4(BCS1L):c.148A>G (p.Thr50Ala) AND Mitochondrial complex III deficiency

Clinical significance:Pathogenic (Last evaluated: Feb 1, 2009)

Review status:(0/4) 0 stars out of maximum of 4 stars

no assertion criteria provided

Based on:
1 submission [Details]
Record status:

Allele description [Variation Report for NM_004328.4(BCS1L):c.148A>G (p.Thr50Ala)]

NM_004328.4(BCS1L):c.148A>G (p.Thr50Ala)

BCS1L:BCS1 homolog, ubiquinol-cytochrome c reductase complex chaperone [Gene - OMIM - HGNC]
Variant type:
single nucleotide variant
Cytogenetic location:
Genomic location:
Preferred name:
NM_004328.4(BCS1L):c.148A>G (p.Thr50Ala)
  • NC_000002.12:g.218661135A>G
  • NG_008018.1:g.6480A>G
  • NM_001257344.1:c.148A>G
  • NM_001318836.1:c.-40-271A>G
  • NM_004328.4:c.148A>G
  • NP_001244273.1:p.Thr50Ala
  • NP_004319.1:p.Thr50Ala
  • LRG_539t1:c.148A>G
  • LRG_539t2:c.148A>G
  • LRG_539:g.6480A>G
  • LRG_539p1:p.Thr50Ala
  • LRG_539p2:p.Thr50Ala
  • NC_000002.11:g.219525858A>G
  • Q9Y276:p.Thr50Ala
Protein change:
UniProtKB: Q9Y276#VAR_064615; OMIM: 603647.0011; dbSNP: rs121908580
NCBI 1000 Genomes Browser:
Molecular consequence:
  • NM_001318836.1:c.-40-271A>G - intron variant - [Sequence Ontology: SO:0001627]
  • NM_004328.4:c.148A>G - missense variant - [Sequence Ontology: SO:0001583]


Mitochondrial complex III deficiency (MC3DN1)
MITOCHONDRIAL COMPLEX III DEFICIENCY, NUCLEAR TYPE 3; Mitochondrial complex III deficiency, nuclear type 1
MedGen: C3541471; Orphanet: 254902; OMIM: 124000

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Assertion and evidence details

Submission AccessionSubmitterReview Status
(Assertion method)
Clinical Significance
(Last evaluated)
SCV000026732OMIMno assertion criteria providedPathogenic
(Feb 1, 2009)
germlineliterature only

PubMed (1)
[See all records that cite this PMID]

Summary from all submissions

EthnicityOriginAffectedIndividualsFamiliesChromosomes testedNumber TestedFamily historyMethod
not providedgermlinenot providednot providednot providednot providednot providednot providedliterature only



Infantile mitochondrial encephalomyopathy with unusual phenotype caused by a novel BCS1L mutation in an isolated complex III-deficient patient.

Blázquez A, Gil-Borlado MC, Morán M, Verdú A, Cazorla-Calleja MR, Martín MA, Arenas J, Ugalde C.

Neuromuscul Disord. 2009 Feb;19(2):143-6. doi: 10.1016/j.nmd.2008.11.016. Epub 2009 Jan 21.

PubMed [citation]

Details of each submission

From OMIM, SCV000026732.4

#EthnicityIndividualsChromosomes TestedFamily HistoryMethodCitations
1not providednot providednot providednot providedliterature only PubMed (1)


In a 4-year-old Spanish boy with isolated mitochondrial complex III deficiency (MC3DN1; 124000), Blazquez et al. (2009) identified a homozygous 148A-G transition in exon 1 of the BCS1L gene, resulting in a thr50-to-ala (T50A) substitution in the mitochondrial sorting sequence. He presented at 6 months of age with psychomotor retardation, failure to thrive, hypotonia, lactic acidosis, and hepatic dysfunction. Physical examination showed unstable head support, poor eye fixation, coarse facies, and epicanthus. There was hypertrichosis of the frontal head zone and limbs, and excessive fat distribution in the upper back, neck, hands and feet, with almost no fat on the limbs. Respiratory chain activity in muscle and fibroblasts showed an isolated complex III defect (58% of normal in muscle, 93% in fibroblasts). At age 4 years, he still showed psychomotor retardation, had developed mild sensorineural hearing loss, and persistent lactic acidemia, but renal function, hair, and iron metabolism were normal. Brain MRI was normal. The mutation was not found in 400 control alleles, and each unaffected parent was heterozygous for the mutation.

OriginAffectedNumber testedTissuePurposeMethodIndividualsAllele frequencyFamiliesCo-occurrences
1germlinenot providednot providednot providednot providednot providednot providednot providednot provided

Last Updated: Mar 30, 2019

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