2-149570057-A-G

Position:

• chr2-149570057-A-G

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM1 PM2

The NM_015702.3(MMADHC):​c.808T>C​(p.Trp270Arg) variant causes a missense change. The variant allele was found at a frequency of 0.00000274 in 1,461,478 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: MMADHC NM_015702.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.81

Genes affected

MMADHC (HGNC:25221): (metabolism of cobalamin associated D) This gene encodes a mitochondrial protein that is involved in an early step of vitamin B12 metabolism. Vitamin B12 (cobalamin) is essential for normal development and survival in humans. Mutations in this gene cause methylmalonic aciduria and homocystinuria type cblD (MMADHC), a disorder of cobalamin metabolism that is characterized by decreased levels of the coenzymes adenosylcobalamin and methylcobalamin. Pseudogenes have been identified on chromosomes 11 and X.[provided by RefSeq, Nov 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM1: In a mutagenesis_site Decreases methylcobalamin levels. (size 0) in uniprot entity MMAD_HUMAN
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MMADHC	NM_015702.3	c.808T>C	p.Trp270Arg	missense_variant	8/8	ENST00000303319.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MMADHC	ENST00000303319.10	c.808T>C	p.Trp270Arg	missense_variant	8/8	1	NM_015702.3	P1
MMADHC	ENST00000422782.2	c.910T>C	p.Trp304Arg	missense_variant	9/9	5
MMADHC	ENST00000428879.5	c.808T>C	p.Trp270Arg	missense_variant	7/7	2		P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461478 Hom.: 0 Cov.: 31 AF XY: 0.00000413 AC XY: 3 AN XY: 727042

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.0000662

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Methylmalonic aciduria and homocystinuria type cblD Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 24, 2021

This sequence change replaces tryptophan with arginine at codon 270 of the MMADHC protein (p.Trp270Arg). The tryptophan residue is highly conserved and there is a moderate physicochemical difference between tryptophan and arginine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with MMADHC-related conditions. 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: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.24	D
BayesDel_noAF	Uncertain	0.11
CADD	Uncertain	24
DANN	Uncertain	0.98
DEOGEN2	Uncertain	0.77	D;D;D
Eigen	Uncertain	0.37
Eigen_PC	Uncertain	0.41
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Benign	0.81	.;T;T
M_CAP	Benign	0.076	D
MetaRNN	Uncertain	0.60	D;D;D
MetaSVM	Uncertain	0.24	D
MutationAssessor	Uncertain	2.3	M;M;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Pathogenic	0.81	D
PROVEAN	Pathogenic	-10	D;D;D
REVEL	Pathogenic	0.71
Sift	Benign	0.22	T;T;T
Sift4G	Benign	0.33	T;T;T
Polyphen		0.96	D;D;P
Vest4		0.31
MutPred		0.77		.;.;Gain of methylation at W304 (P = 0.0228);
MVP		0.86
MPC		0.14
ClinPred		1.0	D
GERP RS		5.0
Varity_R		0.89
gMVP		0.81

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr2-150426571;