rs587776889

Variant names:

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong

The NM_015506.3(MMACHC):c.609G>A(p.Trp203*) variant causes a stop gained change. The variant allele was found at a frequency of 0.00000929 in 1,614,172 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 0.000026 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000075 ( 0 hom. )

Consequence

MMACHC
NM_015506.3 stop_gained

Scores

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:18O:1

Conservation

PhyloP100: 3.61

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 18 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. There are 22 pathogenic variants in the truncated region.

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 1-45508975-G-A is Pathogenic according to our data. Variant chr1-45508975-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 30800.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr1-45508975-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MMACHC	NM_015506.3 link	c.609G>A	p.Trp203*	stop_gained	Exon 4 of 4	ENST00000401061.9	NP_056321.2	Q9Y4U1
MMACHC	NM_001330540.2 link	c.438G>A	p.Trp146*	stop_gained	Exon 4 of 4		NP_001317469.1	Q9Y4U1A0A0C4DGU2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MMACHC	ENST00000401061.9 link	c.609G>A	p.Trp203*	stop_gained	Exon 4 of 4	2	NM_015506.3	ENSP00000383840.4		Q9Y4U1
MMACHC	ENST00000616135.1 link	c.438G>A	p.Trp146*	stop_gained	Exon 4 of 5	2		ENSP00000478859.1		A0A0C4DGU2

Frequencies

GnomAD3 genomes

AF:

0.0000263

AC:

AN:

152164

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:

0.000768

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000441

AC:

AN:

249554

Hom.:

AF XY:

0.0000443

AC XY:

AN XY:

135394

show subpopulations

Gnomad AFR exome

AF:

0.0000646

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.000556

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:

0.00000752

AC:

AN:

1461890

Hom.:

Cov.:

AF XY:

0.00000963

AC XY:

AN XY:

727246

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.000202

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

8.99e-7

Gnomad4 OTH exome

AF:

0.0000331

GnomAD4 genome

AF:

0.0000263

AC:

AN:

152282

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74466

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.000770

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000474

Hom.:

Bravo

AF:

0.000102

ExAC

AF:

0.0000331

AC:

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:18Other:1

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Cobalamin C disease

Pathogenic:15

May 13, 2021

Genetics and Prenatal Diagnosis Center, The First Affiliated Hospital of Zhengzhou University

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Mar 17, 2017

Counsyl

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Sep 01, 2010

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Feb 16, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Trp203*) in the MMACHC gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 80 amino acid(s) of the MMACHC protein. This variant is present in population databases (rs587776889, gnomAD 0.05%). This premature translational stop signal has been observed in individuals with MMACHC-related conditions (PMID: 16311595, 20631720, 23954310, 25772322, 27383490, 28327205). ClinVar contains an entry for this variant (Variation ID: 30800). For these reasons, this variant has been classified as Pathogenic. -

Developmental and Behavioral Pediatrics, First Affiliated Hospital of Jilin University

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Dec 01, 2023

Precision Medicine Center, Zhengzhou University

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

PVS1,PM2_p,PM3 -

Apr 23, 2020

Neurology Department, Peking University First Hospital

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: research

- -

Apr 11, 2023

Genome-Nilou Lab

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Jul 13, 2017

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

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: The MMACHC c.609G>A (p.Trp203X) variant results in a premature termination codon, predicted to cause a truncated or absent MMACHC protein due to nonsense mediated decay, which are commonly known mechanisms for disease. One in silico tool predicts a damaging outcome for this variant. This variant was found in 4/121366 control chromosomes at a frequency of 0.000033, which does not exceed the estimated maximal expected allele frequency of a pathogenic MMACHC variant (0.0030542). The variant has been reported in numerous affected individuals in the homozygous and compound heterozygous state, and there is evidence the variant may be a founder mutation in the Chinese population (Lerner-Ellis_2009). In addition, multiple clinical diagnostic laboratories/reputable databases classified this variant as pathogenic. Taken together, this variant is classified as pathogenic. -

Biochemistry Laboratory of CDMU, Chengde Medical University

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: case-control

- -

Feb 28, 2020

Beijing Key Laboratry for Genetics of Birth Defects, Beijing Children's Hospital

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

May 02, 2024

Fulgent Genetics, Fulgent Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Mar 28, 2024

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Oct 02, 2021

3billion

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Stop-gained (nonsense): predicted to result in a loss or disruption of normal protein function through nonsense-mediated decay (NMD) or protein truncation. Multiple pathogenic variants are reported downstream of the variant (PVS1_VS). It is observed at an extremely low frequency in the gnomAD v2.1.1 dataset (total allele frequency: 0.0000441, PM2). he variant was observed in trans with a pathogenic variant (NM_015506.2: c.394C>T) as compound heterozygous (3billion dataset, PM3). The variant has been reported multiple times as an established pathogenic variant (ClinVar ID: VCV000030800.12). Therefore, this variant is classified as pathogenic according to the recommendation of ACMG/AMP guideline. -

Juno Genomics, Hangzhou Juno Genomics, Inc

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

PM2_Supporting+PM3_VeryStrong+PP4+PVS1_Strong -

not provided

Pathogenic:2

Jul 25, 2017

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Trp203Ter variant creates a termination codon in the MMACHC protein at codon 203 in exon 4 which is predicted to result in a truncated or absent protein product. In a cohort of 204 individuals suspected with inborn errors in cobalamin metabolism, the p.Trp203Ter was identified in the MMACHC gene from 7 individuals with pathogenic bi-allelic variants, including 5 homozygotes (Lerner-Ellis et. al. 2006). Furthermore, the p.Trp203Ter was observed in 52 out of 71 Chinese patients, including 15 homozygotes with elevated methylmalonic aciduria (MMA) and homocystinuria (HC), whereby haplotype analysis determined that it may have been caused by a founder effect in this population (Liu et. al. 2010). This variant is reported in ClinVar (Variation ID: 30800) as pathogenic. It is listed in the Genome Aggregation Database (gnomAD) with an overall population frequency of 0.004 percent (identified on 10 out of 246,224 chromosomes). Based on these observations the p.Trp203Ter is pathogenic. -

Jan 17, 2024

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Nonsense variant predicted to result in protein truncation, as the last 80 amino acids are lost, and other loss-of-function variants have been reported downstream in HGMD; This variant is associated with the following publications: (PMID: 26283149, 26149271, 34704411, 33691766, 34474183, 34102818, 35361390, 35085585, 23591356, 22995991, 20631720, 21055272, 26563984, 27383490, 27751223, 29042959, 28327205, 29581464, 29340559, 29068997, 30712249, 29045954, 31178897, 30863077, 30564975, 31574870, 31203424, 31697851, 31965297, 30157807, 32443968, 31998365, 29731766, 32005694, 34539730, 32957924, 32943488, 32901917, 32712949, 32778825, 33473346, 33914258, 34076870, 33982424, 35578252, 35935352, 35709987, 34953813, 33327995, 35193651, 31328266, 35660814, 16311595, 32746869) -

Methylmalonic acidemia with homocystinuria cblC

Pathogenic:1

Sep 16, 2020

Natera, Inc.

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Disorders of Intracellular Cobalamin Metabolism

Other:1

GeneReviews

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

Common in people of Chinese ancestry. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.37

BayesDel_noAF

Pathogenic

0.57

CADD

Pathogenic

DANN

Uncertain

0.99

Eigen

Pathogenic

0.96

Eigen_PC

Pathogenic

0.84

FATHMM_MKL

Uncertain

0.96

Vest4

0.73

GERP RS

5.7

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