rs780926592

Variant names:

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM1PM2

The NM_015506.3(MMACHC):c.548T>C(p.Val183Ala) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000229 in 1,614,064 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V183I) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000025 ( 0 hom. )

Consequence

MMACHC
NM_015506.3 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:6

Conservation

PhyloP100: 7.52

Variant links:

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]

MMACHC links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 4 ACMG points.

PM1

In a chain Cyanocobalamin reductase / alkylcobalamin dealkylase (size 281) in uniprot entity MMAC_HUMAN there are 51 pathogenic changes around while only 14 benign (78%) in NM_015506.3

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MMACHC	NM_015506.3 link	c.548T>C	p.Val183Ala	missense_variant	Exon 4 of 4	ENST00000401061.9	NP_056321.2	Q9Y4U1
MMACHC	NM_001330540.2 link	c.377T>C	p.Val126Ala	missense_variant	Exon 4 of 4		NP_001317469.1	Q9Y4U1A0A0C4DGU2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MMACHC	ENST00000401061.9 link	c.548T>C	p.Val183Ala	missense_variant	Exon 4 of 4	2	NM_015506.3	ENSP00000383840.4		Q9Y4U1
MMACHC	ENST00000616135.1 link	c.377T>C	p.Val126Ala	missense_variant	Exon 4 of 5	2		ENSP00000478859.1		A0A0C4DGU2

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152174

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.000116

AC:

AN:

249544

Hom.:

AF XY:

0.0000812

AC XY:

AN XY:

135388

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.000840

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

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:

0.0000246

AC:

AN:

1461890

Hom.:

Cov.:

AF XY:

0.0000179

AC XY:

AN XY:

727246

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.000648

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:

0.00000629

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152174

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74340

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.0000655

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:

0.00000756

ExAC

AF:

0.0000744

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:6

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Cobalamin C disease

Uncertain:3

Dec 30, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces valine, which is neutral and non-polar, with alanine, which is neutral and non-polar, at codon 183 of the MMACHC protein (p.Val183Ala). This variant is present in population databases (rs780926592, gnomAD 0.07%). This variant has not been reported in the literature in individuals affected with MMACHC-related conditions. ClinVar contains an entry for this variant (Variation ID: 582087). 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. 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. -

Mar 12, 2022

Fulgent Genetics, Fulgent Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Apr 11, 2023

Genome-Nilou Lab

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Inborn genetic diseases

Uncertain:1

Mar 03, 2025

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.548T>C (p.V183A) alteration is located in exon 4 (coding exon 4) of the MMACHC gene. This alteration results from a T to C substitution at nucleotide position 548, causing the valine (V) at amino acid position 183 to be replaced by an alanine (A). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

not provided

Uncertain:1

Apr 07, 2022

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

Methylmalonic acidemia with homocystinuria cblC

Uncertain:1

Jan 17, 2020

Natera, Inc.

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.68

BayesDel_addAF

Pathogenic

0.18

BayesDel_noAF

Pathogenic

0.39

CADD

Pathogenic

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

0.87

D;T

Eigen

Pathogenic

0.81

Eigen_PC

Pathogenic

0.78

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Benign

0.67

T;T

M_CAP

Uncertain

0.17

MetaRNN

Uncertain

0.66

D;D

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

3.2

M;.

PrimateAI

Uncertain

0.61

PROVEAN

Uncertain

-3.1

D;.

REVEL

Pathogenic

0.87

Sift

Uncertain

0.0040

D;.

Sift4G

Uncertain

0.0040

D;D

Polyphen

1.0

D;.

Vest4

0.69

MutPred

0.51

Gain of disorder (P = 0.0274);.;

MVP

0.97

MPC

0.078

ClinPred

0.77

GERP RS

5.7

Varity_R

0.64

gMVP

0.87

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over