NM_000255.4:c.*257A>C

Variant names:

• chr6-49431471-T-G
• rs187747098
• NM_000255.4:c.*257A>C

Variant summary

Our verdict is Likely benign. Variant got -3 ACMG points: 2P and 5B. PM2 BP4_Strong BS1_Supporting

The NM_000255.4(MMUT):​c.*257A>C variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00189 in 247,618 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: 𝑓 0.0022 (1 hom., cov: 32)
  • Exomes 𝑓: 0.0014 (0 hom.)
• Consequence: MMUT NM_000255.4 3_prime_UTR
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.256

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 Likely_benign. Variant got -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.81).
• BS1: Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.00221 (336/152186) while in subpopulation AFR AF= 0.00457 (190/41550). AF 95% confidence interval is 0.00404. There are 1 homozygotes in gnomad4. There are 145 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MMUT	NM_000255.4	c.*257A>C		3_prime_UTR_variant	Exon 13 of 13	ENST00000274813.4	NP_000246.2
MMUT	XM_005249143.4	c.*257A>C		3_prime_UTR_variant	Exon 13 of 13		XP_005249200.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MMUT	ENST00000274813	c.*257A>C		3_prime_UTR_variant	Exon 13 of 13	1	NM_000255.4	ENSP00000274813.3

Frequencies

GnomAD3 genomes AF: 0.00222 AC: 337 AN: 152072 Hom.: 1 Cov.: 32

Gnomad AFR AF: 0.00461

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00203

Gnomad ASJ AF: 0.0274

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000235

Gnomad OTH AF: 0.00191

GnomAD4 exome AF: 0.00137 AC: 131 AN: 95432 Hom.: 0 Cov.: 0 AF XY: 0.00126 AC XY: 63 AN XY: 49878

Gnomad4 AFR exome AF: 0.00504

Gnomad4 AMR exome AF: 0.00114

Gnomad4 ASJ exome AF: 0.0236

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.000118

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.000289

Gnomad4 OTH exome AF: 0.00301

GnomAD4 genome AF: 0.00221 AC: 336 AN: 152186 Hom.: 1 Cov.: 32 AF XY: 0.00195 AC XY: 145 AN XY: 74398

Gnomad4 AFR AF: 0.00457

Gnomad4 AMR AF: 0.00203

Gnomad4 ASJ AF: 0.0274

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000235

Gnomad4 OTH AF: 0.00189

Alfa AF: 0.00154 Hom.: 0

Bravo AF: 0.00251

Asia WGS AF: 0.000289 AC: 1 AN: 3472

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

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

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.81
CADD	Benign	3.2
DANN	Benign	0.64
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		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: rs187747098; hg19: chr6-49399184;