rs369296618

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1_ModeratePM2PP5_Very_Strong

The NM_052845.4(MMAB):​c.700C>T​(p.Gln234Ter) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000165 in 1,613,778 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 Pathogenic (★★).

Frequency

Genomes: 𝑓 0.000033 ( 0 hom., cov: 34)
Exomes 𝑓: 0.00018 ( 0 hom. )

Consequence

MMAB
NM_052845.4 stop_gained

Scores

2
3
2

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:8O:1

Conservation

PhyloP100: 2.75
Variant links:
Genes affected
MMAB (HGNC:19331): (metabolism of cobalamin associated B) This gene encodes a protein that catalyzes the final step in the conversion of vitamin B(12) into adenosylcobalamin (AdoCbl), a vitamin B12-containing coenzyme for methylmalonyl-CoA mutase. Mutations in the gene are the cause of vitamin B12-dependent methylmalonic aciduria linked to the cblB complementation group. Alternatively spliced transcript variants have been found. [provided by RefSeq, Apr 2011]

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 12 ACMG points.

PVS1
Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.0704 CDS is truncated, and there are 1 pathogenic variants in the truncated region.
PM2
Very rare variant in population databases, with high coverage;
PP5
Variant 12-109557081-G-A is Pathogenic according to our data. Variant chr12-109557081-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 203820.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr12-109557081-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene Transcript HGVSc HGVSp Effect #exon/exons MANE Protein UniProt
MMABNM_052845.4 linkuse as main transcriptc.700C>T p.Gln234Ter stop_gained 9/9 ENST00000545712.7 NP_443077.1

Ensembl

Gene Transcript HGVSc HGVSp Effect #exon/exons TSL MANE Protein Appris UniProt
MMABENST00000545712.7 linkuse as main transcriptc.700C>T p.Gln234Ter stop_gained 9/91 NM_052845.4 ENSP00000445920 P1

Frequencies

GnomAD3 genomes
AF:
0.0000328
AC:
5
AN:
152208
Hom.:
0
Cov.:
34
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:
0.00
Gnomad MID
AF:
0.00
Gnomad NFE
AF:
0.0000735
Gnomad OTH
AF:
0.00
GnomAD3 exomes
AF:
0.0000318
AC:
8
AN:
251474
Hom.:
0
AF XY:
0.0000294
AC XY:
4
AN XY:
135912
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:
0.00
Gnomad FIN exome
AF:
0.00
Gnomad NFE exome
AF:
0.0000615
Gnomad OTH exome
AF:
0.000163
GnomAD4 exome
AF:
0.000179
AC:
261
AN:
1461570
Hom.:
0
Cov.:
32
AF XY:
0.000176
AC XY:
128
AN XY:
727104
show subpopulations
Gnomad4 AFR exome
AF:
0.0000896
Gnomad4 AMR exome
AF:
0.00
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:
0.000228
Gnomad4 OTH exome
AF:
0.0000828
GnomAD4 genome
AF:
0.0000328
AC:
5
AN:
152208
Hom.:
0
Cov.:
34
AF XY:
0.00
AC XY:
0
AN XY:
74356
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:
0.00
Gnomad4 NFE
AF:
0.0000735
Gnomad4 OTH
AF:
0.00
Alfa
AF:
0.000112
Hom.:
0
Bravo
AF:
0.0000416
ESP6500AA
AF:
0.00
AC:
0
ESP6500EA
AF:
0.000116
AC:
1
ExAC
AF:
0.0000330
AC:
4
EpiCase
AF:
0.000109
EpiControl
AF:
0.000119

ClinVar

Significance: Pathogenic
Submissions summary: Pathogenic:8Other:1
Revision: criteria provided, multiple submitters, no conflicts
LINK: link

Submissions by phenotype

Methylmalonic aciduria, cblB type Pathogenic:6Other:1
Pathogenic, criteria provided, single submitterclinical testingLabcorp Genetics (formerly Invitae), LabcorpJan 08, 2024This sequence change creates a premature translational stop signal (p.Gln234*) in the MMAB gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 17 amino acid(s) of the MMAB protein. This variant is present in population databases (rs369296618, gnomAD 0.006%). This premature translational stop signal has been observed in individuals with methylmalonic aciduria (PMID: 16410054). ClinVar contains an entry for this variant (Variation ID: 203820). Algorithms developed to predict the effect of variants on protein structure and function are not available or were not evaluated for this variant. Experimental studies have shown that this premature translational stop signal affects MMAB function (PMID: 21604717). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -
not provided, no classification providedliterature onlyGeneReviews-- -
Pathogenic, no assertion criteria providedclinical testingBaumgartner lab, University Children's Hospital ZurichJun 01, 2021- -
Pathogenic, no assertion criteria providedclinical testingNatera, Inc.Sep 16, 2020- -
Pathogenic, criteria provided, single submitterclinical testingLaboratory for Molecular Medicine, Mass General Brigham Personalized MedicineNov 10, 2014The p.Gln234X variant in MMAB has been reported in 4 compound heterozygous and 2 homozygous individuals with methylmalonic aciduria (Lerner-Ellis 2006). This variant has been identified in 0.012% (1/8600) of European American chromosomes by the NHLBI Exome Sequencing Project (http://evs.gs.washington.edu/EVS/; dbSNP rs369296618). Although this variant has been seen in the general population, its frequency is low enough to be consistent with a recessive carrier frequency. This nonsense variant leads to a premature termination codon at position 234. This alteration occurs within the last exon and is therefore more likely to escape nonsense mediated decay (NMD) and result in a truncated protein. In vitro functional studies provide some evidence that the p.Gln234X variant may impact protein function (Lofgren 2011); however, in vitro assays may not accurately represent biological function. In summary, although additional studies are required to fully establish its clinical significance, the p.Gln234X variant is likely pathogenic. -
Pathogenic, criteria provided, single submitterclinical testingBaylor GeneticsMar 06, 2024- -
Pathogenic, criteria provided, single submitterclinical testingVictorian Clinical Genetics Services, Murdoch Childrens Research InstituteJul 17, 2023Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Pathogenic. Following criteria are met: 0102 - Loss of function is a known mechanism of disease in this gene and is associated with vitamin B12-responsive methylmalonic aciduria cblB type (MIM#251110). (I) 0106 - This gene is associated with autosomal recessive disease. (I) 0115 - Variants in this gene are known to have variable expressivity (GeneReviews). (I) 0205 - Variant is predicted to result in a truncated protein (premature termination codon is NOT located at least 54 nucleotides upstream of the final exon-exon junction) with less than 1/3 of the protein sequence affected. (SP) 0251 - This variant is heterozygous. (I) 0304 - Variant is present in gnomAD <0.01 for a recessive condition (v2 & v3: 13 heterozygotes, 0 homozygotes). (SP) 0604 - Variant is not located in an established domain, motif, hotspot or informative constraint region. (I) 0801 - This variant has very strong previous evidence of pathogenicity in unrelated individuals. It has been reported in multiple individuals with methylmalonic aciduria cblB type (PMID: 16410054) and regarded as pathogenic in ClinVar. It is usually associated with a milder phenotype and later onset (GeneReviews). (SP) 1206 - This variant has been shown to be paternally inherited. Father was tested by Fulgent laboratory. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -
not provided Pathogenic:1
Pathogenic, criteria provided, single submitterclinical testingCenter for Pediatric Genomic Medicine, Children's Mercy Hospital and ClinicsOct 10, 2016- -
Methylmalonic acidemia Pathogenic:1
Pathogenic, criteria provided, single submitterclinical testingWomen's Health and Genetics/Laboratory Corporation of America, LabCorpDec 17, 2018Variant summary: MMAB c.700C>T (p.Gln234X) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. The variant allele was found at a frequency of 3.2e-05 in 246252 control chromosomes. c.700C>T has been reported in the literature in multiple individuals affected with Methylmalonic Acidemia (Lerner-Ellis_2006, O'Shea_2012). One publication reports that ibroblasts from patients with this mutation in homozygous or heterozygous form had higher levels of MCM function than most cblB fibroblasts however that was not found to correlated with any reduction in severity of clinical presentation (Lerner-Ellis_2006). These data indicate that the variant is very likely to be associated with disease. Two clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as pathogenic. Based on the evidence outlined above, the variant was classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name
Calibrated prediction
Score
Prediction
BayesDel_addAF
Pathogenic
0.49
D
BayesDel_noAF
Pathogenic
0.48
CADD
Pathogenic
38
DANN
Uncertain
0.99
Eigen
Uncertain
0.66
Eigen_PC
Uncertain
0.47
FATHMM_MKL
Benign
0.72
D
MutationTaster
Benign
1.0
D;D
Vest4
0.46
GERP RS
4.5

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: rs369296618; hg19: chr12-109994886; API