Genetic Variant MMAA:p.Gly278Val (chr4-145654007-G-T) – ACMG Classification: Likely_pathogenic (8 pts)

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM2PM5PP3_Strong

The NM_172250.3(MMAA):c.833G>T(p.Gly278Val) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000616 in 1,461,836 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 13/22 in silico tools predict a damaging outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G278D) has been classified as Likely pathogenic.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 0.0000062 ( 0 hom. )

Consequence

MMAA
NM_172250.3 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 9.56

Publications

0 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:

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ACMG classification

Classification was made for transcript

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr4-145654007-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 552542.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.99

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein
MMAA	NM_172250.3 link	c.833G>T	p.Gly278Val	missense_variant	Exon 6 of 7	ENST00000649156.2	NP_758454.1
MMAA	NM_001375644.1 link	c.833G>T	p.Gly278Val	missense_variant	Exon 6 of 7		NP_001362573.1
MMAA	XM_011531684.4 link	c.833G>T	p.Gly278Val	missense_variant	Exon 6 of 7		XP_011529986.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MMAA	ENST00000649156.2 link	c.833G>T	p.Gly278Val	missense_variant	Exon 6 of 7		NM_172250.3	ENSP00000497008.1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

0.00000616

AC:

AN:

1461836

Hom.:

Cov.:

AF XY:

0.00000688

AC XY:

AN XY:

727218

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26130

East Asian (EAS)

AF:

0.00

AC:

AN:

39686

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53418

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5764

European-Non Finnish (NFE)

AF:

0.00000630

AC:

AN:

1111982

Other (OTH)

AF:

0.0000166

AC:

AN:

60394

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.497

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

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.98

BayesDel_addAF

Pathogenic

0.56

BayesDel_noAF

Pathogenic

0.57

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

0.85

D;.;D;D;D;D

Eigen

Pathogenic

1.2

Eigen_PC

Pathogenic

1.1

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Pathogenic

1.0

.;D;.;.;D;D

M_CAP

Pathogenic

0.61

MetaRNN

Pathogenic

0.99

D;D;D;D;D;D

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

4.1

H;.;H;H;H;.

PhyloP100

9.6

PrimateAI

Pathogenic

0.84

PROVEAN

Pathogenic

-8.3

.;.;D;.;.;.

REVEL

Pathogenic

0.98

Sift

Pathogenic

0.0

.;.;D;.;.;.

Sift4G

Pathogenic

0.0010

.;.;D;.;.;D

Polyphen

1.0

D;.;D;D;D;.

Vest4

0.98, 0.99

MutPred

0.93

Loss of disorder (P = 0.0739);.;Loss of disorder (P = 0.0739);Loss of disorder (P = 0.0739);Loss of disorder (P = 0.0739);Loss of disorder (P = 0.0739);

MVP

0.99

MPC

0.62

ClinPred

1.0

GERP RS

5.8

Varity_R

1.0

gMVP

0.94

Mutation Taster

=156/144

polymorphism

(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

Computational scores

Splicing

Publications

Other links and lift over