rs765822392

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 (★★).

Frequency

Genomes: 𝑓 0.000033 ( 0 hom., cov: 32)
Exomes 𝑓: 0.000036 ( 0 hom. )

Consequence

MMACHC
NM_015506.3 missense

Scores

2
17

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]

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 9 pathogenic changes around while only 2 benign (82%) 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
MMACHCNM_015506.3 linkuse as main transcriptc.800G>A p.Arg267Gln missense_variant 4/4 ENST00000401061.9 NP_056321.2
MMACHCNM_001330540.2 linkuse as main transcriptc.629G>A p.Arg210Gln missense_variant 4/4 NP_001317469.1

Ensembl

Gene Transcript HGVSc HGVSp Effect #exon/exons TSL MANE Protein Appris UniProt
MMACHCENST00000401061.9 linkuse as main transcriptc.800G>A p.Arg267Gln missense_variant 4/42 NM_015506.3 ENSP00000383840 P1
MMACHCENST00000616135.1 linkuse as main transcriptc.629G>A p.Arg210Gln missense_variant 4/52 ENSP00000478859

Frequencies

GnomAD3 genomes
AF:
0.0000329
AC:
5
AN:
152078
Hom.:
0
Cov.:
32
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:
17
AN:
248864
Hom.:
0
AF XY:
0.0000666
AC XY:
9
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:
52
AN:
1461726
Hom.:
0
Cov.:
32
AF XY:
0.0000385
AC XY:
28
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:
5
AN:
152078
Hom.:
0
Cov.:
32
AF XY:
0.0000539
AC XY:
4
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.:
0
Bravo
AF:
0.0000227
ExAC
AF:
0.0000662
AC:
8
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 submitterclinical testingGenome-Nilou LabApr 11, 2023- -
Uncertain significance, criteria provided, single submitterclinical testingRevvity Omics, RevvityJul 05, 2021- -
Uncertain significance, criteria provided, single submitterclinical testingLabcorp Genetics (formerly Invitae), LabcorpAug 30, 2021This 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 submitterclinical testingNeuberg 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. -
Uncertain significance, criteria provided, single submitterclinical testingMyriad Genetics, Inc.Oct 20, 2021NM_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. -
not specified Uncertain:1
Uncertain significance, criteria provided, single submitterclinical testingWomen's Health and Genetics/Laboratory Corporation of America, LabCorpJan 11, 2024Variant 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 submitterclinical testingAmbry GeneticsSep 12, 2022The 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 submitterclinical testingGeneDxApr 19, 2021Also 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 providedclinical testingNatera, Inc.Sep 16, 2020- -

Computational scores

Source: dbNSFP v4.3

Name
Calibrated prediction
Score
Prediction
AlphaMissense
Benign
0.077
BayesDel_addAF
Benign
-0.17
T
BayesDel_noAF
Benign
-0.20
CADD
Benign
17
DANN
Uncertain
1.0
DEOGEN2
Benign
0.030
T;T
Eigen
Benign
-0.83
Eigen_PC
Benign
-0.84
FATHMM_MKL
Benign
0.084
N
LIST_S2
Benign
0.64
T;T
M_CAP
Benign
0.068
D
MetaRNN
Benign
0.062
T;T
MetaSVM
Uncertain
-0.023
T
MutationAssessor
Benign
1.1
L;.
MutationTaster
Benign
1.0
N
PrimateAI
Benign
0.28
T
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
T
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.

Other links and lift over

dbSNP: rs765822392; hg19: chr1-45974838; API