rs121918257

chr6-49459145-G-Achr6-49459145-G-C

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1 PM2 PM5 PP3_Moderate PP5_Very_Strong

The NM_000255.4(MMUT):c.322C>T(p.Arg108Cys) variant causes a missense change. The variant allele was found at a frequency of 0.0000229 in 1,614,052 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 11/19 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R108H) has been classified as Pathogenic.

• Frequency:
  • Genomes: 𝑓 0.000020 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000023 (0 hom.)
• Consequence: MMUT NM_000255.4 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:11 O:1
• Conservation: PhyloP100: 4.71

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 16 ACMG points.

• PM1: In a strand (size 5) in uniprot entity MUTA_HUMAN there are 9 pathogenic changes around while only 0 benign (100%) 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 chr6-49459144-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 100707.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.895
• PP5: Variant 6-49459145-G-A is Pathogenic according to our data. Variant chr6-49459145-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 1887.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr6-49459145-G-A is described in Lovd as [Pathogenic]. Variant chr6-49459145-G-A is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MMUT	NM_000255.4	c.322C>T	p.Arg108Cys	missense_variant	2/13	ENST00000274813.4
MMUT	XM_005249143.4	c.322C>T	p.Arg108Cys	missense_variant	2/13

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MMUT	ENST00000274813.4	c.322C>T	p.Arg108Cys	missense_variant	2/13	1	NM_000255.4	P1

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152094 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000242

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

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: 0.0000147

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000119 AC: 30 AN: 251326 Hom.: 0 AF XY: 0.0000736 AC XY: 10 AN XY: 135840

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000839

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

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: 0.0000233 AC: 34 AN: 1461840 Hom.: 0 Cov.: 31 AF XY: 0.0000138 AC XY: 10 AN XY: 727226

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.000626

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000756

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.0000331

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152212 Hom.: 0 Cov.: 33 AF XY: 0.0000269 AC XY: 2 AN XY: 74414

Gnomad4 AFR AF: 0.0000241

Gnomad4 AMR AF: 0.0000654

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

Bravo AF: 0.0000604

ExAC AF: 0.0000824 AC: 10

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:11 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:4

Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Mar 09, 2021	In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 16281286, 30564975, 24464670, 31622506, 31998365, 31525265, 31466887, 27578510, 29330964, 26454439) -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jan 29, 2024	This sequence change replaces arginine, which is basic and polar, with cysteine, which is neutral and slightly polar, at codon 108 of the MUT protein (p.Arg108Cys). This variant is present in population databases (rs121918257, gnomAD 0.08%). This missense change has been observed in individual(s) with methylmalonic acidemia (PMID: 2661559, 16281286, 17075691, 22614770, 23045948, 24059531, 24464670, 27578510). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 1887). 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%. This variant disrupts the p.Arg108 amino acid residue in MUT. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 16281286, 17113806, 22614770, 23430940, 25750861). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, no assertion criteria provided	clinical testing	Clinical Genetics DNA and cytogenetics Diagnostics Lab, Erasmus MC, Erasmus Medical Center	-	- -
Likely pathogenic, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -

Methylmalonic acidemia Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Jan 14, 2019	Variant summary: MUT c.322C>T (p.Arg108Cys) results in a non-conservative amino acid change located in the Methylmalonyl-CoA mutase, alpha chain, catalytic domain of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.00011 in 246146 control chromosomes. c.322C>T has been reported in the literature in multiple individuals affected with Methylmalonic Acidemia (Worgan_2006, Harrington_2016). These data indicate that the variant is very likely to be associated with disease. At least one publication reports experimental evidence evaluating an impact on protein function. The most pronounced variant effect results in <10% of normal activity as measured by decreased incorporation of label from carbon-14 labeled propionate into cellular macromolecules (Worgan_2006). Three clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Rady Children's Institute for Genomic Medicine, Rady Children's Hospital San Diego	-	This variant has been previously reported as a compound heterozygous and homozygous change in patients with methylmalonic acidemia (PMID: 16281286, 17075691, 24059531, 23045948, 2661559, 22614770, 24464670, 27578510). The c.322C>T (p.Arg108Cys) variant is present in the heterozygous state in the gnomAD population database at a frequency of 0.012% (30/251326), and is absent in the homozygous state; thus it is presumed to be rare. The c.322C>T (p.Arg108Cys) variant affects a highly conserved amino acid and is predicted by multiple in silico tools to have a deleterious effect on protein function. Based on the available evidence, the c.322C>T (p.Arg108Cys) variant is classified as a Pathogenic. -

METHYLMALONIC ACIDURIA, mut(0) TYPE Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Genetic Services Laboratory, University of Chicago	Apr 06, 2016	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	Jan 01, 2006	- -

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

Pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Feb 18, 2022	- -
not provided, no classification provided	literature only	GeneReviews	-	mut(0) enzymatic subtype when homozygous -

not specified Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 18, 2021

The c.322C>T (p.R108C) alteration is located in exon 2 (coding exon 1) of the MUT gene. This alteration results from a C to T substitution at nucleotide position 322, causing the arginine (R) at amino acid position 108 to be replaced by a cysteine (C). Based on data from gnomAD, the T allele has an overall frequency of 0.01% (30/251326) total alleles studied. The highest observed frequency was 0.08% (29/34552) of Latino alleles. This mutation has been reported in the homozygous and compound heterozygous state in several individuals with MUT-related methylmalonic aciduria (Worgan, 2006; Zhang, 2019; Han, 2020). Another alteration at the same codon, p.R108H (c.323G>A), has been detected in individuals with MUT-related methylmalonic aciduria in conjunction with a second MUT alteration (Worgan, 2006; Lempp, 2007). This amino acid position is highly conserved in available vertebrate species. This alteration is predicted to be deleterious by in silico analysis. Based on the available evidence, this alteration is classified as pathogenic. -

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

Pathogenic, no assertion criteria provided

clinical testing

Natera, Inc.

Sep 16, 2020

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.30	D
BayesDel_noAF	Pathogenic	0.58
Cadd	Pathogenic	33
Dann	Pathogenic	1.0
Eigen	Pathogenic	0.81
Eigen_PC	Pathogenic	0.69
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.92	D
M_CAP	Pathogenic	0.44	D
MetaRNN	Pathogenic	0.90	D
MetaSVM	Pathogenic	1.0	D
MutationTaster	Benign	1.0	A
PrimateAI	Pathogenic	0.89	D
PROVEAN	Pathogenic	-7.9	D
REVEL	Pathogenic	0.96
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Vest4		0.97
MVP		0.99
MPC		0.57
ClinPred		0.99	D
GERP RS		5.6
gMVP		0.95

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: rs121918257; hg19: chr6-49426858;