1-45508982-C-T

Position:

chr1-45508982-C-T

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM1PM2PM5PP3_StrongPP5

The NM_015506.3(MMACHC):c.616C>T(p.Arg206Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000682 in 1,614,050 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 Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R206P) has been classified as Likely pathogenic.

Frequency

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

Exomes 𝑓: 0.0000068 ( 0 hom. )

Consequence

MMACHC
NM_015506.3 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:5U:1

Conservation

PhyloP100: -0.0290

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 Pathogenic. Variant got 11 ACMG points.

PM1

In a chain Cyanocobalamin reductase / alkylcobalamin dealkylase (size 281) in uniprot entity MMAC_HUMAN there are 50 pathogenic changes around while only 14 benign (78%) in NM_015506.3

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr1-45508983-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 848845.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.992

PP5

Variant 1-45508982-C-T is Pathogenic according to our data. Variant chr1-45508982-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 203832.We mark this variant Likely_pathogenic, oryginal submissions are: {Pathogenic=3, Likely_pathogenic=1, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
MMACHC	NM_015506.3 linkuse as main transcript	c.616C>T	p.Arg206Trp	missense_variant	4/4	ENST00000401061.9
MMACHC	NM_001330540.2 linkuse as main transcript	c.445C>T	p.Arg149Trp	missense_variant	4/4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
MMACHC	ENST00000401061.9 linkuse as main transcript	c.616C>T	p.Arg206Trp	missense_variant	4/4	2	NM_015506.3	P1
MMACHC	ENST00000616135.1 linkuse as main transcript	c.445C>T	p.Arg149Trp	missense_variant	4/5	2

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152168

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

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:

0.0000941

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.00000401

AC:

AN:

249530

Hom.:

AF XY:

0.00

AC XY:

AN XY:

135378

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000556

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:

0.00000684

AC:

AN:

1461882

Hom.:

Cov.:

AF XY:

0.00000550

AC XY:

AN XY:

727244

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.0000504

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00000450

Gnomad4 OTH exome

AF:

0.0000166

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152168

Hom.:

Cov.:

AF XY:

0.0000134

AC XY:

AN XY:

74350

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.0000941

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.00000378

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:5Uncertain:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Cobalamin C disease

Pathogenic:5Uncertain:1

Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jan 18, 2024	This sequence change replaces arginine, which is basic and polar, with tryptophan, which is neutral and slightly polar, at codon 206 of the MMACHC protein (p.Arg206Trp). This variant is present in population databases (no rsID available, gnomAD 0.006%). This missense change has been observed in individual(s) with methylmalonic aciduria and homocystinuria (PMID: 16311595, 20610126, 20631720, 26149271). 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: 203832). 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. This variant disrupts the p.Arg206 amino acid residue in MMACHC. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 30157807). 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	Counsyl	Jan 31, 2018	- -
Uncertain significance, criteria provided, single submitter	reference population	Soonchunhyang University Bucheon Hospital, Soonchunhyang University Medical Center	Mar 18, 2016	- -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Dec 02, 2023	- -
Pathogenic, criteria provided, single submitter	clinical testing	Clinical Genomics Laboratory, Washington University in St. Louis	Apr 05, 2024	The MMACHC c.616C>T (p.Arg206Trp) variant has been reported in at least four individuals in the compound heterozygous state affected with methylmalonic aciduria and homocystinuria, cblC type (Frattini D et al., PMID: 20610126; Lerner-Ellis JP et al., PMID: 16311595; Liu MY et al., PMID: 20631720; Zhong Y et al., PMID: 26149271). Another variant in the same codon, c.617G>A (p.Arg206Gln), has been reported in affected individuals and is considered pathogenic (Hu S et al., PMID: 30157807, ClinVar Variation ID: 848845). This variant is only observed on 1/249,530 alleles in the general population (gnomAD v.2.1.1), indicating it is not a common variant. Computational predictors indicate that the variant is damaging, evidence that correlates with impact to MMACHC function. This variant has been reported in the ClinVar database as a germline pathogenic variant by three groups, likely pathogenic by one group and a variant of uncertain significance by one group. Based on available information and the ACMG/AMP guidelines for variant interpretation (Richards S et al., PMID: 25741868), this variant is classified as pathogenic. -
Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	Sep 02, 2020	- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.82

BayesDel_addAF

Pathogenic

0.40

BayesDel_noAF

Pathogenic

0.50

CADD

Uncertain

DANN

Pathogenic

1.0

DEOGEN2

Pathogenic

0.93

D;T

Eigen

Uncertain

0.40

Eigen_PC

Uncertain

0.28

FATHMM_MKL

Uncertain

0.91

LIST_S2

Uncertain

0.92

D;D

M_CAP

Pathogenic

0.68

MetaRNN

Pathogenic

0.99

D;D

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

3.4

M;.

MutationTaster

Benign

1.0

PrimateAI

Uncertain

0.59

PROVEAN

Pathogenic

-7.8

D;.

REVEL

Pathogenic

0.89

Sift

Pathogenic

0.0

D;.

Sift4G

Pathogenic

0.0

D;D

Polyphen

1.0

D;.

Vest4

0.94

MutPred

0.96

Loss of disorder (P = 0.0516);.;

MVP

0.97

MPC

0.081

ClinPred

1.0

GERP RS

1.4

Varity_R

0.97

gMVP

0.98

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