rs397515486
Variant summary
Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM2PM5PP5
The NM_005334.3(HCFC1):c.218C>T(p.Ala73Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A73T) has been classified as Pathogenic.
Frequency
Consequence
NM_005334.3 missense
Scores
Clinical Significance
Conservation
Publications
- methylmalonic acidemia with homocystinuria, type cblXInheritance: XL Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: G2P, Ambry Genetics, Orphanet, Labcorp Genetics (formerly Invitae)
 - X-linked intellectual disabilityInheritance: XL Classification: DEFINITIVE Submitted by: ClinGen, Illumina
 - non-syndromic X-linked intellectual disabilityInheritance: XL Classification: SUPPORTIVE Submitted by: Orphanet
 
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ACMG classification
Our verdict: Uncertain_significance. The variant received 5 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes  Cov.: 23 
GnomAD4 exome Data not reliable, filtered out with message: AC0;AS_VQSR AF:  0.00  AC: 0AN: 1073459Hom.:  0  Cov.: 30 AF XY:  0.00  AC XY: 0AN XY: 344387 
GnomAD4 genome  Cov.: 23 
ClinVar
Submissions by phenotype
Methylmalonic acidemia with homocystinuria, type cblX    Pathogenic:2Uncertain:1 
This sequence change replaces alanine with valine at codon 73 of the HCFC1 protein (p.Ala73Val). The alanine residue is highly conserved and there is a small physicochemical difference between alanine and valine. This variant is not present in population databases (ExAC no frequency). This variant has been observed in individual(s) with cobalamin X deficiency (PMID: 24011988, 25167861). ClinVar contains an entry for this variant (Variation ID: 66985). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt HCFC1 protein function. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -
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Cobalamin C disease    Pathogenic:1 
Variant summary: HCFC1 c.218C>T (p.Ala73Val) results in a non-conservative amino acid change located in the the first kelch domain (Yu_2013) of the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 161726 control chromosomes (gnomAD). c.218C>T has been reported in the literature in individuals affected with Methylmalonic Acidemia With Homocystinuria as well as one individual whose parents were negative for the mutation, suggesting that it arose de novo (Yu_2013, Redin_2014). Functional studies report this variant results in reducing the level of MMACHC expression and in biochemical abnormalities (Yu_2013, Quintana_2014). One ClinVar submitter (evaluation after 2014) cites the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
not provided    Pathogenic:1 
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Intellectual disability    Pathogenic:1 
present in the affected brother -
Disorders of Intracellular Cobalamin Metabolism    Other:1 
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Computational scores
Source: 
Splicing
 Find out detailed SpliceAI scores and Pangolin per-transcript scores at