12-109573347-C-T

Variant names:

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM1PM2PP3_Moderate

The NM_052845.4(MMAB):c.134G>A(p.Arg45Lys) variant causes a missense, splice region change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,460,934 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★).

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

MMAB
NM_052845.4 missense, splice_region

Scores

Splicing: ADA: 0.9999

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 3.38

Publications

0 publications found

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]

MMAB links:

MVK (HGNC:7530): (mevalonate kinase) This gene encodes the peroxisomal enzyme mevalonate kinase. Mevalonate is a key intermediate, and mevalonate kinase a key early enzyme, in isoprenoid and sterol synthesis. Mevalonate kinase deficiency caused by mutation of this gene results in mevalonic aciduria, a disease characterized psychomotor retardation, failure to thrive, hepatosplenomegaly, anemia and recurrent febrile crises. Defects in this gene also cause hyperimmunoglobulinaemia D and periodic fever syndrome, a disorder characterized by recurrent episodes of fever associated with lymphadenopathy, arthralgia, gastrointestinal dismay and skin rash. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jul 2014]

MVK Gene-Disease associations (from GenCC):

porokeratosis 3, disseminated superficial actinic type
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
hyperimmunoglobulinemia D with periodic fever
Inheritance: AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: Orphanet, G2P
mevalonic aciduria
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Labcorp Genetics (formerly Invitae), Orphanet
disseminated superficial actinic porokeratosis
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
porokeratosis of Mibelli
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

MVK links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

PM1

In a chain Corrinoid adenosyltransferase MMAB (size 217) in uniprot entity MMAB_HUMAN there are 24 pathogenic changes around while only 8 benign (75%) in NM_052845.4

PM2

Very rare variant in population databases, with high coverage;

PP3

Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MMAB	NM_052845.4 link	c.134G>A	p.Arg45Lys	missense_variant, splice_region_variant	Exon 1 of 9	ENST00000545712.7	NP_443077.1	Q96EY8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MMAB	ENST00000545712.7 link	c.134G>A	p.Arg45Lys	missense_variant, splice_region_variant	Exon 1 of 9	1	NM_052845.4	ENSP00000445920.1		Q96EY8

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1460934

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

726778

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:

33462

American (AMR)

AF:

0.00

AC:

AN:

44708

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26126

East Asian (EAS)

AF:

0.00

AC:

AN:

39688

South Asian (SAS)

AF:

0.00

AC:

AN:

86218

European-Finnish (FIN)

AF:

0.00

AC:

AN:

52828

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5716

European-Non Finnish (NFE)

AF:

8.99e-7

AC:

AN:

1111836

Other (OTH)

AF:

0.00

AC:

AN:

60352

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), 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

GnomAD4 genome

Cov.:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Methylmalonic aciduria, cblB type

Uncertain:1

Dec 29, 2023

Fulgent Genetics, Fulgent Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.088

BayesDel_addAF

Uncertain

0.045

BayesDel_noAF

Benign

-0.17

CADD

Pathogenic

(source)

DANN

Uncertain

0.99

DEOGEN2

Benign

0.18

T;.;T

Eigen

Benign

-0.073

Eigen_PC

Benign

0.089

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Benign

0.66

T;T;T

M_CAP

Benign

0.066

MetaRNN

Benign

0.17

T;T;T

MetaSVM

Benign

-0.59

MutationAssessor

Benign

1.9

L;.;.

PhyloP100

3.4

PrimateAI

Benign

0.33

PROVEAN

Benign

-0.50

N;.;.

REVEL

Benign

0.16

Sift

Benign

0.17

T;.;.

Sift4G

Benign

0.11

T;T;T

Polyphen

0.030

B;.;.

Vest4

0.18

MutPred

0.14

Gain of ubiquitination at R45 (P = 0.0014);Gain of ubiquitination at R45 (P = 0.0014);Gain of ubiquitination at R45 (P = 0.0014);

MVP

0.87

MPC

0.23

ClinPred

0.75

GERP RS

4.7

PromoterAI

-0.0077

Neutral

(source)

Varity_R

0.25

gMVP

0.40

Mutation Taster

=265/35

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.98

SpliceAI score (max)

0.71

Details are displayed if max score is > 0.2

DS_DL_spliceai

0.71

Position offset: 0

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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12-109573347-C-T

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