chr6-49459437-TA-T

Variant names:

• chr6-49459437-TA-T
• rs1437477079
• NM_000255.4:c.29delT

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000255.4(MMUT):​c.29delT​(p.Leu10TyrfsTer7) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: MMUT NM_000255.4 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 0.247
• Publications: 1 publications found

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]

MMUT Gene-Disease associations (from GenCC):

• methylmalonic aciduria due to methylmalonyl-CoA mutase deficiency

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: ClinGen, Labcorp Genetics (formerly Invitae), G2P
• vitamin B12-unresponsive methylmalonic acidemia type mut-

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• vitamin B12-unresponsive methylmalonic acidemia type mut0

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 18 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 353 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 6-49459437-TA-T is Pathogenic according to our data. Variant chr6-49459437-TA-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 1072649.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MMUT	NM_000255.4	c.29delT	p.Leu10TyrfsTer7	frameshift_variant	Exon 2 of 13	ENST00000274813.4	NP_000246.2
MMUT	XM_005249143.4	c.29delT	p.Leu10TyrfsTer7	frameshift_variant	Exon 2 of 13		XP_005249200.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MMUT	ENST00000274813.4	c.29delT	p.Leu10TyrfsTer7	frameshift_variant	Exon 2 of 13	1	NM_000255.4	ENSP00000274813.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1460870 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 726768

African (AFR) AF: 0.00 AC: 0 AN: 33454

American (AMR) AF: 0.00 AC: 0 AN: 44658

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26112

East Asian (EAS) AF: 0.00 AC: 0 AN: 39696

South Asian (SAS) AF: 0.00 AC: 0 AN: 86230

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52902

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5550

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111916

Other (OTH) AF: 0.00 AC: 0 AN: 60352

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1

Apr 21, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. Loss-of-function variants in MUT are known to be pathogenic (PMID: 15781192). This variant has not been reported in the literature in individuals with MUT-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change creates a premature translational stop signal (p.Leu10Tyrfs*7) in the MUT gene. It is expected to result in an absent or disrupted protein product. -

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

Dec 18, 2021

Fulgent Genetics, Fulgent Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		0.25

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

Other links and lift over

dbSNP: rs1437477079; hg19: chr6-49427150; COSMIC: COSV51273465; COSMIC: COSV51273465;