rs764173488

Positions:

• chr6-49447749-A-T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000255.4(MMUT):​c.1481T>A​(p.Leu494Ter) variant causes a stop gained change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000411 in 1,459,756 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: MMUT NM_000255.4 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 8.86

Genes affected

MMUT (HGNC:7526): (methylmalonyl-CoA mutase) This gene encodes the mitochondrial enzyme methylmalonyl Coenzyme A mutase. In humans, the product of this gene is a vitamin B12-dependent enzyme which catalyzes the isomerization of methylmalonyl-CoA to succinyl-CoA, while in other species this enzyme may have different functions. Mutations in this gene may lead to various types of methylmalonic aciduria. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 6-49447749-A-T is Pathogenic according to our data. Variant chr6-49447749-A-T is described in ClinVar as [Pathogenic]. Clinvar id is 551275.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MMUT	NM_000255.4	c.1481T>A	p.Leu494Ter	stop_gained	8/13	ENST00000274813.4	NP_000246.2
MMUT	XM_005249143.4	c.1481T>A	p.Leu494Ter	stop_gained	8/13		XP_005249200.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MMUT	ENST00000274813.4	c.1481T>A	p.Leu494Ter	stop_gained	8/13	1	NM_000255.4	ENSP00000274813	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000799 AC: 2 AN: 250250 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135270

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000109

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000411 AC: 6 AN: 1459756 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 726278

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000152

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 26, 2023

For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 551275). This premature translational stop signal has been observed in individual(s) with methylmalonic acidemia (PMID: 16490061, 23479330). This variant is present in population databases (rs764173488, gnomAD 0.01%). This sequence change creates a premature translational stop signal (p.Leu494*) in the MUT gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in MUT are known to be pathogenic (PMID: 15781192). -

Methylmalonic aciduria due to methylmalonyl-CoA mutase deficiency Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Counsyl

Mar 28, 2017

- -

Methylmalonic acidemia Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Aug 05, 2019

Variant summary: MUT c.1481T>A (p.Leu494X) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory (e.g. p.Arg511X, p.Ala732fsX6). The variant allele was found at a frequency of 8e-06 in 250250 control chromosomes. c.1481T>A has been reported in the literature in multiple homozygous and compound heterozygous individuals affected with Methylmalonic Acidemia (e.g. Sakamoto_2007, Imataka_2013). These data indicate that the variant is very likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Two clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation, and both of them classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.47	D
BayesDel_noAF	Pathogenic	0.65
CADD	Pathogenic	40
DANN	Uncertain	0.99
Eigen	Pathogenic	0.90
Eigen_PC	Pathogenic	0.78
FATHMM_MKL	Pathogenic	0.99	D
MutationTaster	Benign	1.0	A
Vest4		0.99
GERP RS		5.2

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.060		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs764173488; hg19: chr6-49415462;