rs864309728

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1PM2PP5_Moderate

The NM_172250.3(MMAA):c.503delC(p.Thr168MetfsTer10) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,854 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★). Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 0.0000021 ( 0 hom. )

Consequence

MMAA
NM_172250.3 frameshift

Scores

Not classified

Clinical Significance

Pathogenic criteria provided, single submitter P:1O:1

Conservation

PhyloP100: 7.38

Publications

3 publications found

Variant links:

Genes affected

MMAA (HGNC:18871): (metabolism of cobalamin associated A) The protein encoded by this gene is involved in the translocation of cobalamin into the mitochondrion, where it is used in the final steps of adenosylcobalamin synthesis. Adenosylcobalamin is a coenzyme required for the activity of methylmalonyl-CoA mutase. Defects in this gene are a cause of methylmalonic aciduria. [provided by RefSeq, Jul 2008]

MMAA Gene-Disease associations (from GenCC):

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

MMAA links:

ENSG00000248356 (HGNC:):

ENSG00000248356 links:

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ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 12 ACMG points.

PVS1

Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 4-145642425-AC-A is Pathogenic according to our data. Variant chr4-145642425-AC-A is described in ClinVar as Pathogenic. ClinVar VariationId is 218974.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein
MMAA	NM_172250.3 link	c.503delC	p.Thr168MetfsTer10	frameshift_variant	Exon 3 of 7	ENST00000649156.2	NP_758454.1
MMAA	NM_001375644.1 link	c.503delC	p.Thr168MetfsTer10	frameshift_variant	Exon 3 of 7		NP_001362573.1
MMAA	XM_011531684.4 link	c.503delC	p.Thr168MetfsTer10	frameshift_variant	Exon 3 of 7		XP_011529986.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MMAA	ENST00000649156.2 link	c.503delC	p.Thr168MetfsTer10	frameshift_variant	Exon 3 of 7		NM_172250.3	ENSP00000497008.1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

0.00000205

AC:

AN:

1461854

Hom.:

Cov.:

AF XY:

0.00000413

AC XY:

AN XY:

727228

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26134

East Asian (EAS)

AF:

0.0000756

AC:

AN:

39692

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53416

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111988

Other (OTH)

AF:

0.00

AC:

AN:

60394

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.0385499), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.375

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

Cov.:

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1Other:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Methylmalonic aciduria, cblA type

Pathogenic:1Other:1

GeneReviews

Significance:not provided

Review Status:no classification provided

Collection Method:literature only

- -

Feb 24, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

For these reasons, this variant has been classified as Pathogenic. This sequence change creates a premature translational stop signal (p.Thr168Metfs*10) in the MMAA gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in MMAA are known to be pathogenic (PMID: 15523652, 15781192). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with methylmalonic acidemia (PMID: 15308131, 31622506). ClinVar contains an entry for this variant (Variation ID: 218974). -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

PhyloP100

7.4

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

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over