1-45508847-C-G

Position:

• chr1-45508847-C-G

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1 PM2 PP3_Strong PP5_Very_Strong

The NM_015506.3(MMACHC):​c.481C>G​(p.Arg161Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000372 in 1,614,020 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 (★★).

• Frequency:
  • Genomes: 𝑓 0.000020 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: MMACHC NM_015506.3 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 1.66

Genes affected

MMACHC (HGNC:24525): (metabolism of cobalamin associated C) The exact function of the protein encoded by this gene is not known, however, its C-terminal region shows similarity to TonB, a bacterial protein involved in energy transduction for cobalamin (vitamin B12) uptake. Hence, it is postulated that this protein may have a role in the binding and intracellular trafficking of cobalamin. Mutations in this gene are associated with methylmalonic aciduria and homocystinuria type cblC. [provided by RefSeq, Oct 2009]

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PM1: In a chain Cyanocobalamin reductase / alkylcobalamin dealkylase (size 281) in uniprot entity MMAC_HUMAN there are 9 pathogenic changes around while only 2 benign (82%) in NM_015506.3
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.989
• PP5: Variant 1-45508847-C-G is Pathogenic according to our data. Variant chr1-45508847-C-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 813351.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MMACHC	NM_015506.3	c.481C>G	p.Arg161Gly	missense_variant	4/4	ENST00000401061.9	NP_056321.2
MMACHC	NM_001330540.2	c.310C>G	p.Arg104Gly	missense_variant	4/4		NP_001317469.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MMACHC	ENST00000401061.9	c.481C>G	p.Arg161Gly	missense_variant	4/4	2	NM_015506.3	ENSP00000383840	P1
MMACHC	ENST00000616135.1	c.310C>G	p.Arg104Gly	missense_variant	4/5	2		ENSP00000478859

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152148 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000724

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: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461872 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727238

Gnomad4 AFR exome AF: 0.0000896

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: 0.00

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152148 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74344

Gnomad4 AFR AF: 0.0000724

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.0000151

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Cobalamin C disease Pathogenic:4

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Oct 13, 2023	This sequence change replaces arginine, which is basic and polar, with glycine, which is neutral and non-polar, at codon 161 of the MMACHC protein (p.Arg161Gly). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with cobalamin C deficiency (PMID: 16311595). 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: 813351). 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on MMACHC protein function. Experimental studies have shown that this missense change affects MMACHC function (PMID: 25809485, 32457044). This variant disrupts the p.Arg161 amino acid residue in MMACHC. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 16311595, 17853453, 19370762, 19700356, 20219402, 21055272, 22560872, 25687216, 25809485, 26283149, 28218226). 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. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Apr 11, 2023	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Apr 19, 2022	- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Mayo Clinic Laboratories, Mayo Clinic

May 03, 2024

PP3, PM1, PM2, PM5, PS3 -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.93
BayesDel_addAF	Pathogenic	0.53	D
BayesDel_noAF	Pathogenic	0.52
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.93	D;T
Eigen	Uncertain	0.56
Eigen_PC	Uncertain	0.48
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Uncertain	0.89	D;D
M_CAP	Pathogenic	0.47	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.4	M;.
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.69	T
PROVEAN	Pathogenic	-6.5	D;.
REVEL	Pathogenic	0.94
Sift	Pathogenic	0.0	D;.
Sift4G	Pathogenic	0.0	D;D
Polyphen		1.0	D;.
Vest4		0.95
MutPred		0.96		Loss of MoRF binding (P = 0.0457);.;
MVP		0.97
MPC		0.080
ClinPred		1.0	D
GERP RS		3.8
Varity_R		0.98
gMVP		0.99

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: rs370596113; hg19: chr1-45974519;