rs121918258

Positions:

• chr6-49457801-C-A
• chr6-49457801-C-T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000255.4(MMUT):​c.643G>T​(p.Gly215Cys) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,344 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. G215S) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: MMUT NM_000255.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 7.46

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.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 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 chr6-49457801-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 1888.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.992
• PP5: Variant 6-49457801-C-A is Pathogenic according to our data. Variant chr6-49457801-C-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 418341.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MMUT	NM_000255.4	c.643G>T	p.Gly215Cys	missense_variant	3/13	ENST00000274813.4
MMUT	XM_005249143.4	c.643G>T	p.Gly215Cys	missense_variant	3/13

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MMUT	ENST00000274813.4	c.643G>T	p.Gly215Cys	missense_variant	3/13	1	NM_000255.4	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461344 Hom.: 0 Cov.: 30 AF XY: 0.00 AC XY: 0 AN XY: 727012

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Aug 10, 2023	For these reasons, this variant has been classified as Pathogenic. This variant disrupts the p.Gly215 amino acid residue in MUT. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 15643616, 16281286, 16451139). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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. ClinVar contains an entry for this variant (Variation ID: 418341). This missense change has been observed in individual(s) with methylmalonic acidemia (PMID: 16281286, 26790480). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glycine, which is neutral and non-polar, with cysteine, which is neutral and slightly polar, at codon 215 of the MUT protein (p.Gly215Cys). -
Likely pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Apr 20, 2016	The G215C variant has been previously reported in two individuals with methylmalonic acidemia (MMA), one homozygous and one compound heterozygote (Worgan et al., 2006). The G215C variant is a non-conservative amino acid substitution, which is likely to impact secondary protein structure as these residues differ in polarity, charge, size and/or other properties. This substitution occurs at a position that is conserved across species. In silico analysis predicts this variant is probably damaging to the protein structure/function. Missense variants in nearby residues (Q218H, N219Y, and N219D) have been reported in the Human Gene Mutation Database in association with methylmalonic aciduria (Stenson et al., 2014), supporting the functional importance of this region of the protein. Therefore, this variant is likely pathogenic; however, the possibility that it is benign cannot be excluded. However, this result could also be seen if the patient had one allele with the G215C variant and one allele that was partially missing or refractory to amplification. -

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

Pathogenic, criteria provided, single submitter	clinical testing	Neuberg Centre For Genomic Medicine, NCGM	-	The MMUT c.643G>T varianthas been observed to be homozygous as well as in combination with another MMUT variant in individuals affected with methylmalonic acidemia (Worgan et. al., 2006; Harrington et. al., 2016). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: Deleterious; PolyPhen-2: Probably Damaging; AlignGVGD: Class C0). The p.Gly215Cys variant is novel (not in any individuals) in gnomAD Exomes and 1000 Genomes. This variant has been reported to the ClinVar database as Pathogenic/Likely Pathogenic. The amino acid change p.Gly215Cys in MMUT is predicted as conserved by GERP++ and PhyloP across 100 vertebrates. This variant disrupts the p.Gly215 amino acid residue in MMUT. Other variant(s) that disrupt this residue have been observed in individuals with MMUT-related conditions (Acquaviva et. al., 2005; Worgan et. al., 2006), suggesting that it is a clinically significant residue. As a result, variants that disrupt this residue are likely to be causative of disease. For these reasons, this variant has been classified as Pathogenic. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	May 10, 2017	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	30
DANN	Uncertain	1.0
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.54	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	0.99	D
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.89	D
PROVEAN	Pathogenic	-9.0	D
REVEL	Pathogenic	0.97
Sift	Uncertain	0.016	D
Sift4G	Pathogenic	0.0	D
Vest4		0.98
MutPred		0.96		Loss of ubiquitination at K210 (P = 0.0344);
MVP		1.0
MPC		0.50
ClinPred		1.0	D
GERP RS		5.7
gMVP		0.97

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.040		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: rs121918258; hg19: chr6-49425514;