1-45500346-T-A

Variant names:

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM1PM2PP2PP3

The NM_015506.3(MMACHC):c.14T>A(p.Val5Asp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,812 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 Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. V5V) has been classified as Likely benign.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

MMACHC
NM_015506.3 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 0.966

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 was made for transcript

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

PM1

In a chain Cyanocobalamin reductase / alkylcobalamin dealkylase (size 281) in uniprot entity MMAC_HUMAN there are 56 pathogenic changes around while only 15 benign (79%) in NM_015506.3

PM2

Very rare variant in population databases, with high coverage;

PP2

Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 28 curated pathogenic missense variants (we use a threshold of 10). The gene has 7 curated benign missense variants. Gene score misZ: -1.0759 (below the threshold of 3.09). Trascript score misZ: -0.13772 (below the threshold of 3.09). GenCC associations: The gene is linked to methylmalonic aciduria and homocystinuria type cblC.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.754

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MMACHC	NM_015506.3 link	c.14T>A	p.Val5Asp	missense_variant	Exon 1 of 4	ENST00000401061.9	NP_056321.2	Q9Y4U1
MMACHC	NM_001330540.2 link	c.-209T>A		5_prime_UTR_variant	Exon 1 of 4		NP_001317469.1	Q9Y4U1A0A0C4DGU2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MMACHC	ENST00000401061.9 link	c.14T>A	p.Val5Asp	missense_variant	Exon 1 of 4	2	NM_015506.3	ENSP00000383840.4		Q9Y4U1
MMACHC	ENST00000616135.1 link	c.-158T>A		5_prime_UTR_variant	Exon 1 of 5	2		ENSP00000478859.1		A0A0C4DGU2

Frequencies

GnomAD3 genomes

Cov.:

GnomAD2 exomes

AF:

0.00000801

AC:

AN:

249574

AF XY:

0.00

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000579

Gnomad ASJ exome

AF:

0.00

Gnomad EAS 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:

0.00000137

AC:

AN:

1461812

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

727202

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33478

American (AMR)

AF:

0.0000447

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39698

South Asian (SAS)

AF:

0.00

AC:

AN:

86252

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53420

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5708

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1112010

Other (OTH)

AF:

0.00

AC:

AN:

60386

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000378

ExAC

AF:

0.00000827

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Cobalamin C disease

Uncertain:1

Aug 31, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces valine with aspartic acid at codon 5 of the MMACHC protein (p.Val5Asp). The valine residue is moderately conserved and there is a large physicochemical difference between valine and aspartic acid. This variant is present in population databases (rs780981680, ExAC 0.009%). This variant has not been reported in the literature in individuals affected with MMACHC-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: "Deleterious"; 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

Uncertain

0.39

BayesDel_addAF

Pathogenic

0.19

BayesDel_noAF

Pathogenic

0.21

CADD

Uncertain

(source)

DANN

Uncertain

0.98

DEOGEN2

Benign

0.38

Eigen

Uncertain

0.31

Eigen_PC

Uncertain

0.27

FATHMM_MKL

Benign

0.69

LIST_S2

Benign

0.80

M_CAP

Pathogenic

0.61

MetaRNN

Pathogenic

0.75

MetaSVM

Pathogenic

0.83

MutationAssessor

Uncertain

2.3

PhyloP100

0.97

PrimateAI

Uncertain

0.54

PROVEAN

Uncertain

-2.9

REVEL

Pathogenic

0.72

Sift

Uncertain

0.0010

Sift4G

Pathogenic

0.0010

Polyphen

0.97

Vest4

0.61

MutPred

0.41

Gain of loop (P = 0.0013);

MVP

0.99

MPC

0.065

ClinPred

0.98

GERP RS

3.4

PromoterAI

-0.0015

Neutral

(source)

Varity_R

0.89

gMVP

0.91

Mutation Taster

=75/25

polymorphism

(source)

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

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1-45500346-T-A

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over