Genetic Variant MMAB:c.134+6T>A (chr12-109573341-A-T) – ACMG Classification: Uncertain_significance (0 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2BP4_Moderate

The NM_052845.4(MMAB):c.134+6T>A variant causes a splice region, intron change. The variant allele was found at a frequency of 0.00000137 in 1,460,892 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 2/3 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (no stars).

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

MMAB
NM_052845.4 splice_region, intron

Scores

Splicing: ADA: 0.9562

Clinical Significance

Uncertain significance no assertion criteria provided U:1

Conservation

PhyloP100: 4.01

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: Uncertain_significance. The variant received 0 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.33).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MMAB	NM_052845.4 link	c.134+6T>A		splice_region_variant, intron_variant	Intron 1 of 8	ENST00000545712.7	NP_443077.1	Q96EY8
MVK	XM_047428873.1 link	c.56A>T	p.His19Leu	missense_variant	Exon 1 of 11		XP_047284829.1
MVK	XM_017019313.3 link	c.-245A>T		5_prime_UTR_variant	Exon 1 of 10		XP_016874802.1	F5H8H2
MMAB	NR_038118.2 link	n.158+6T>A		splice_region_variant, intron_variant	Intron 1 of 9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MMAB	ENST00000545712.7 link	c.134+6T>A		splice_region_variant, intron_variant	Intron 1 of 8	1	NM_052845.4	ENSP00000445920.1		Q96EY8

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

0.00000137

AC:

AN:

1460892

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

726770

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33462

American (AMR)

AF:

0.00

AC:

AN:

44712

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26126

East Asian (EAS)

AF:

0.00

AC:

AN:

39686

South Asian (SAS)

AF:

0.00

AC:

AN:

86218

European-Finnish (FIN)

AF:

0.00

AC:

AN:

52810

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5712

European-Non Finnish (NFE)

AF:

0.00000180

AC:

AN:

1111816

Other (OTH)

AF:

0.00

AC:

AN:

60350

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

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: no assertion criteria provided

LINK: link

Submissions by phenotype

Methylmalonic aciduria, cblB type

Uncertain:1

Apr 14, 2025

Natera, Inc.

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.33

CADD

Benign

(source)

DANN

Benign

0.89

PhyloP100

4.0

PromoterAI

-0.037

Neutral

(source)

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.0

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Benign

0.96

dbscSNV1_RF

Benign

0.65

SpliceAI score (max)

0.40

Details are displayed if max score is > 0.2

DS_DL_spliceai

0.40

Position offset: 6

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

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over