rs796052002

Variant names:

• chr6-49453686-G-A
• rs796052002
• NM_000255.4:c.982C>T

Variant summary

Our verdict is Pathogenic. The variant received 19 ACMG points: 19P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_000255.4(MMUT):​c.982C>T​(p.Leu328Phe) variant causes a missense change. The variant allele was found at a frequency of 0.00000248 in 1,613,038 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 Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. L328P) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: MMUT NM_000255.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 5.13
• Publications: 9 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 19 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 4 uncertain in NM_000255.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr6-49453685-A-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 552752.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 150 curated pathogenic missense variants (we use a threshold of 10). The gene has 9 curated benign missense variants. Gene score misZ: 0.22855 (below the threshold of 3.09). Trascript score misZ: 1.0842 (below the threshold of 3.09). GenCC associations: The gene is linked to vitamin B12-unresponsive methylmalonic acidemia type mut-, methylmalonic aciduria due to methylmalonyl-CoA mutase deficiency, vitamin B12-unresponsive methylmalonic acidemia type mut0.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.988
• PP5: Variant 6-49453686-G-A is Pathogenic according to our data. Variant chr6-49453686-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 203844.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.982C>T	p.Leu328Phe	missense_variant	Exon 5 of 13	ENST00000274813.4	NP_000246.2
MMUT	XM_005249143.4	c.982C>T	p.Leu328Phe	missense_variant	Exon 5 of 13		XP_005249200.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MMUT	ENST00000274813.4	c.982C>T	p.Leu328Phe	missense_variant	Exon 5 of 13	1	NM_000255.4	ENSP00000274813.3

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 152040 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.000478

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1460998 Hom.: 0 Cov.: 30 AF XY: 0.00000275 AC XY: 2 AN XY: 726880

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

American (AMR) AF: 0.00 AC: 0 AN: 44712

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26110

East Asian (EAS) AF: 0.00 AC: 0 AN: 39564

South Asian (SAS) AF: 0.00 AC: 0 AN: 86236

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53404

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5760

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111406

Other (OTH) AF: 0.0000497 AC: 3 AN: 60352

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 152040 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74276

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 41400

American (AMR) AF: 0.00 AC: 0 AN: 15262

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5190

South Asian (SAS) AF: 0.00 AC: 0 AN: 4828

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10552

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68016

Other (OTH) AF: 0.000478 AC: 1 AN: 2094

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Methylmalonic aciduria due to methylmalonyl-CoA mutase deficiency Pathogenic:2

Jan 04, 2022

Fulgent Genetics, Fulgent Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Apr 06, 2017

Counsyl

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -

not provided Pathogenic:1

Feb 23, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces leucine, which is neutral and non-polar, with phenylalanine, which is neutral and non-polar, at codon 328 of the MUT protein (p.Leu328Phe). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with methylmalonic aciduria (PMID: 15643616, 17113806, 27167370). ClinVar contains an entry for this variant (Variation ID: 203844). 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 MUT protein function with a positive predictive value of 95%. Experimental studies have shown that this missense change affects MUT function (PMID: 25125334). For these reasons, this variant has been classified as Pathogenic. -

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

Aug 25, 2020

Natera, Inc.

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Methylmalonic acidemia Pathogenic:1

Feb 09, 2017

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

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: The MUT c.982C>T (p.Leu328Phe) variant involves the alteration of a conserved nucleotide and is located in substrate-binding TIM barrel of the protein (Lempp_2007, Dndar_2012). 3/4 in silico tools predict a damaging outcome for this variant (SNPs&GO not captured due to low reliability index). This variant is absent in 121168 control chromosomes including broad and large population of ExAC. This variant is reported as a pathogenic variant in literature and has been found in several patients with methylmalonic academia in homozygous as well as in compound heterozygous state with other potentially pathogenic variants. Functional studies for this variant are consistent with defective enzymatic activity. One clinical diagnostic laboratory has classified this variant as pathogenic. Taken together, this variant is classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.88
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.56
CADD	Pathogenic	26
DANN	Pathogenic	1.0
Eigen	Pathogenic	0.97
Eigen_PC	Pathogenic	0.89
FATHMM_MKL	Uncertain	0.89	D
LIST_S2	Pathogenic	1.0	D
M_CAP	Pathogenic	0.59	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.0	D
PhyloP100		5.1
PrimateAI	Uncertain	0.77	T
PROVEAN	Uncertain	-3.9	D
REVEL	Pathogenic	0.95
Sift	Uncertain	0.0010	D
Sift4G	Uncertain	0.0070	D
Vest4		0.93
MutPred		0.93		Gain of methylation at R327 (P = 0.0888);
MVP		0.99
MPC		0.50
ClinPred		1.0	D
GERP RS		5.6
gMVP		0.90
Mutation Taster		=8/92	disease causing (ClinVar)

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: rs796052002; hg19: chr6-49421399;