rs765822392

Positions:

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 4P and 4B. PM1PM2BP4_Strong

The NM_015506.3(MMACHC):c.800G>A(p.Arg267Gln) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000353 in 1,613,804 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict a benign outcome for this variant. 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. R267W) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000033 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000036 ( 0 hom. )

Consequence

MMACHC
NM_015506.3 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:8B:1

Conservation

PhyloP100: -0.0580

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 0 ACMG points.

PM1

In a chain Cyanocobalamin reductase / alkylcobalamin dealkylase (size 281) in uniprot entity MMAC_HUMAN there are 49 pathogenic changes around while only 14 benign (78%) in NM_015506.3

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (MetaRNN=0.06174785).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MMACHC	NM_015506.3 linkuse as main transcript	c.800G>A	p.Arg267Gln	missense_variant	4/4	ENST00000401061.9	NP_056321.2	Q9Y4U1
MMACHC	NM_001330540.2 linkuse as main transcript	c.629G>A	p.Arg210Gln	missense_variant	4/4		NP_001317469.1	Q9Y4U1A0A0C4DGU2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MMACHC	ENST00000401061.9 linkuse as main transcript	c.800G>A	p.Arg267Gln	missense_variant	4/4	2	NM_015506.3	ENSP00000383840.4		Q9Y4U1
MMACHC	ENST00000616135.1 linkuse as main transcript	c.629G>A	p.Arg210Gln	missense_variant	4/5	2		ENSP00000478859.1		A0A0C4DGU2

Frequencies

GnomAD3 genomes

AF:

0.0000329

AC:

AN:

152078

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000415

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000294

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000683

AC:

AN:

248864

Hom.:

AF XY:

0.0000666

AC XY:

AN XY:

135110

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.000163

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.000106

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000356

AC:

AN:

1461726

Hom.:

Cov.:

AF XY:

0.0000385

AC XY:

AN XY:

727166

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.000139

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.0000324

Gnomad4 OTH exome

AF:

0.0000497

GnomAD4 genome

AF:

0.0000329

AC:

AN:

152078

Hom.:

Cov.:

AF XY:

0.0000539

AC XY:

AN XY:

74270

show subpopulations

Gnomad4 AFR

AF:

0.0000241

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.000415

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000294

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000434

Hom.:

Bravo

AF:

0.0000227

ExAC

AF:

0.0000662

AC:

EpiCase

AF:

0.000109

EpiControl

AF:

0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:8Benign:1

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Cobalamin C disease

Uncertain:5

Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Apr 11, 2023	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Jul 05, 2021	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Aug 30, 2021	This sequence change replaces arginine with glutamine at codon 267 of the MMACHC protein (p.Arg267Gln). The arginine residue is moderately conserved and there is a small physicochemical difference between arginine and glutamine. This variant is present in population databases (rs765822392, ExAC 0.02%). This missense change has been observed in individual(s) with methylmalonic aciduria and homocystinuria (PMID: 16311595, 19370762, 24126030). In at least one individual the data is consistent with the variant being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 378150). Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0". The glutamine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect 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. -
Uncertain significance, criteria provided, single submitter	clinical testing	Myriad Genetics, Inc.	Oct 20, 2021	NM_015506.2(MMACHC):c.800G>A(R267Q) is a missense variant classified as a variant of uncertain significance in the context of methylmalonic aciduria and homocystinuria, cblC type. R267Q has been observed in cases with relevant disease (PMID: 16311595, 24126030). Functional assessments of this variant are not available in the literature. R267Q has been observed in population frequency databases (gnomAD: SAS 0.02%). In summary, there is insufficient evidence to classify NM_015506.2(MMACHC):c.800G>A(R267Q) as pathogenic or benign. Please note: this variant was assessed in the context of healthy population screening. -
Uncertain significance, criteria provided, single submitter	clinical testing	Neuberg Centre For Genomic Medicine, NCGM	-	The observed missense variant c.800G>A(p.Arg267Gln) in MMACHC gene has been reported previously in individuals with cblC deficiency who also harbored c.271dupA but it is not known whether these variants occurred in cis/trans chromosomes (Gizicki et al., 2014). Also, this variant is described as a benign and possibly benign variant (Lerner-Ellis JP, et al., 2009). The c.800G>A variant has 0.01% allele frequency in gnomAD Exomes. This variant has been reported to the ClinVar database as Uncertain Significance. The amino acid Arginine at position 267 is changed to a Glutamine changing protein sequence and it might alter its composition and physico-chemical properties.The amino acid change p.Arg267Gln in MMACHC is predicted as conserved by GERP++. For these reasons, this variant has been classified as Uncertain Significance. -

not specified

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Jan 11, 2024

Variant summary: MMACHC c.800G>A (p.Arg267Gln) results in a conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 6.8e-05 in 248864 control chromosomes (gnomAD). This frequency is not significantly higher than estimated for a pathogenic variant in MMACHC causing Methylmalonic Acidemia With Homocystinuria (6.8e-05 vs 0.0032), allowing no conclusion about variant significance. c.800G>A has been reported in the literature in individuals affected with Cobalamin C Disease (Methylmalonic Aciduria With Homocystinuria), however the majority of these reports identified the variant as part of a complex allele with c.271dupA (p.R91Kfs) (e.g., Lerner-Ellis_2006, Lerner-Ellis_2009, Koutmos_2011, Gizicki_2014, Stranneheim_2021, Kacpura_2022). These reports therefore do not provide unequivocal conclusions about association of the variant with Methylmalonic Acidemia With Homocystinuria. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 24126030, 35156754, 19370762, 16311595, 33726816, 21697092). ClinVar contains an entry for this variant (Variation ID: 378150). Based on the evidence outlined above, the variant was classified as uncertain significance. -

Inborn genetic diseases

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 12, 2022

The c.800G>A (p.R267Q) alteration is located in exon 4 (coding exon 4) of the MMACHC gene. This alteration results from a G to A substitution at nucleotide position 800, causing the arginine (R) at amino acid position 267 to be replaced by a glutamine (Q). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Apr 19, 2021

Also observed in an individual with cblC deficiency who also harbored c.271dupA but it is not known whether these variants occurred on the same (in cis) or opposite (in trans) chromosomes (Gizicki et al., 2014); Described as a benign and possibly benign variant (Lerner-Ellis et al., 2009; Koutmos et al., 2011); In silico analysis supports that this missense variant does not alter protein structure/function; This variant is associated with the following publications: (PMID: 21697092, 24126030, 19370762, 16311595) -

Methylmalonic acidemia with homocystinuria cblC

Benign:1

Likely benign, no assertion criteria provided

clinical testing

Natera, Inc.

Sep 16, 2020

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.077

BayesDel_addAF

Benign

-0.17

BayesDel_noAF

Benign

-0.20

CADD

Benign

DANN

Uncertain

1.0

DEOGEN2

Benign

0.030

T;T

Eigen

Benign

-0.83

Eigen_PC

Benign

-0.84

FATHMM_MKL

Benign

0.084

LIST_S2

Benign

0.64

T;T

M_CAP

Benign

0.068

MetaRNN

Benign

0.062

T;T

MetaSVM

Uncertain

-0.023

MutationAssessor

Benign

1.1

L;.

PrimateAI

Benign

0.28

PROVEAN

Benign

0.10

N;.

REVEL

Benign

0.17

Sift

Benign

0.078

T;.

Sift4G

Benign

0.29

T;T

Polyphen

0.0020

B;.

Vest4

0.060

MutPred

0.17

Loss of MoRF binding (P = 0.0463);.;

MVP

0.74

MPC

0.012

ClinPred

0.034

GERP RS

2.5

Varity_R

0.030

gMVP

0.35

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