1-45508981-C-G

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong

The NM_015506.3(MMACHC):c.615C>G(p.Tyr205*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000124 in 1,614,078 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 (★★). Synonymous variant affecting the same amino acid position (i.e. Y205Y) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000012 ( 0 hom. )

Consequence

MMACHC
NM_015506.3 stop_gained

Scores

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:10

Conservation

PhyloP100: 2.40

Publications

12 publications found

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 Gene-Disease associations (from GenCC):

methylmalonic aciduria and homocystinuria type cblC
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, Myriad Women’s Health, ClinGen, G2P, Orphanet

MMACHC links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 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 29 pathogenic variants in the truncated region.

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 1-45508981-C-G is Pathogenic according to our data. Variant chr1-45508981-C-G is described in ClinVar as Pathogenic. ClinVar VariationId is 281007.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MMACHC	NM_015506.3 link	c.615C>G	p.Tyr205*	stop_gained	Exon 4 of 4	ENST00000401061.9	NP_056321.2
MMACHC	NM_001330540.2 link	c.444C>G	p.Tyr148*	stop_gained	Exon 4 of 4		NP_001317469.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MMACHC	ENST00000401061.9 link	c.615C>G	p.Tyr205*	stop_gained	Exon 4 of 4	2	NM_015506.3	ENSP00000383840.4
MMACHC	ENST00000616135.1 link	c.444C>G	p.Tyr148*	stop_gained	Exon 4 of 5	2		ENSP00000478859.1

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152194

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000131

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000240

AC:

AN:

249538

AF XY:

0.0000148

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.000116

Gnomad ASJ exome

AF:

0.00

Gnomad EAS 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:

0.0000123

AC:

AN:

1461884

Hom.:

Cov.:

AF XY:

0.0000110

AC XY:

AN XY:

727246

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.000112

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26134

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.0000348

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53412

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00000899

AC:

AN:

1112012

Other (OTH)

AF:

0.00

AC:

AN:

60396

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.486

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152194

Hom.:

Cov.:

AF XY:

0.0000134

AC XY:

AN XY:

74360

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41436

American (AMR)

AF:

0.000131

AC:

AN:

15274

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5200

South Asian (SAS)

AF:

0.00

AC:

AN:

4834

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10628

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68034

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.550

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.0000340

ExAC

AF:

0.0000165

AC:

EpiCase

AF:

0.0000545

EpiControl

AF:

0.00

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:10

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Cobalamin C disease

Pathogenic:6

Nov 22, 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.615C>G (p.Tyr205X) 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. A truncation downstream of this position, c.666C>A (p.Tyr222X) has been classified as pathogenic by our laboratory. This variant was found in 5/246214 control chromosomes (gnomAD) at a frequency of 0.0000203, which does not exceed the estimated maximal expected allele frequency of a pathogenic MMACHC variant (0.0030542). The variant of interst has been reported in multiple affected compound heterozygote and homozygote cblC pts (Lerner-Ellis_2006). In addition, a clinical diagnostic laboratory classified this variant as pathogenic. Taken together, this variant is classified as pathogenic.

Apr 06, 2017

Counsyl

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com.

Apr 11, 2023

Genome-Nilou Lab

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Jan 22, 2024

Fulgent Genetics, Fulgent Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Oct 29, 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.Tyr205*) in the MMACHC gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 78 amino acid(s) of the MMACHC protein. This variant is present in population databases (rs747527726, gnomAD 0.009%). This premature translational stop signal has been observed in individuals with cobalamin C deficiency (PMID: 16311595, 19914430, 20631720, 25388550). ClinVar contains an entry for this variant (Variation ID: 281007). 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.

Mar 16, 2024

Baylor Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

not provided

Pathogenic:3

Oct 07, 2020

GeneDx

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Nonsense variant in the C-terminus predicted to result in protein truncation, as the last 78 amino acids are lost, and other loss-of-function variants have been reported downstream in the Human Gene Mutation Database (Stenson et al., 2014); Not observed at a significant frequency in large population cohorts (Lek et al., 2016); This variant is associated with the following publications: (PMID: 33587123, 19760748, 16311595, 20631720, 25388550, 30863077)

May 04, 2016

Eurofins Ntd Llc (ga)

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Feb 03, 2020

Athena Diagnostics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant is expected to result in the loss of a functional protein. This variant has been identified homozygous and compound heterozygous in multiple individuals with clinical features associated with this gene (PMID: 16311595, 19370762, 19760748, 23746552). The frequency of this variant in the general population is consistent with pathogenicity for a recessive disorder (http://gnomad.broadinstitute.org).This observation is not an independent occurrence and has been identified in the same individual by RCIGM, the other laboratory participating in the GEMINI study.

Methylmalonic acidemia with homocystinuria cblC

Pathogenic:1

Sep 16, 2020

Natera, Inc.

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:clinical testing

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.47

BayesDel_noAF

Pathogenic

0.57

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

DEOGEN2

Benign

0.0

.;.

Eigen

Uncertain

0.66

Eigen_PC

Uncertain

0.52

FATHMM_MKL

Uncertain

0.97

LIST_S2

Benign

0.0

.;.

MetaRNN

Benign

0.0

.;.

MutationAssessor

Benign

0.0

.;.

PhyloP100

2.4

PROVEAN

Benign

0.0

.;.

REVEL

Benign

0.0

Sift

Pathogenic

0.0

.;.

Sift4G

Pathogenic

0.0

.;.

Vest4

0.76

GERP RS

3.8

Mutation Taster

=0/200

disease causing (ClinVar)

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over