Genetic Variant MMAA:c.-68C>T (chr4-145619405-C-T) – ACMG Classification: Likely_benign (-2 pts)

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2BP4_Strong

The NM_172250.3(MMAA):c.-68C>T variant causes a splice region change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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 (★).

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 0.0 ( 0 hom. )

Failed GnomAD Quality Control

Consequence

MMAA
NM_172250.3 splice_region

Scores

Splicing: ADA: 0.0004352

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: -4.37

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_benign. The variant received -2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.81).

Transcripts

RefSeq

Gene	Transcript	HGVSc	Effect	Exon rank	MANE	Protein	UniProt
MMAA	NM_172250.3 link	c.-68C>T	splice_region_variant	Exon 1 of 7	ENST00000649156.2	NP_758454.1	Q8IVH4
MMAA	NM_172250.3 link	c.-68C>T	5_prime_UTR_variant	Exon 1 of 7	ENST00000649156.2	NP_758454.1	Q8IVH4
MMAA	NM_001375644.1 link	c.-310C>T	5_prime_UTR_variant	Exon 1 of 7		NP_001362573.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MMAA	ENST00000649156.2 link	c.-68C>T		splice_region_variant	Exon 1 of 7		NM_172250.3	ENSP00000497008.1		Q8IVH4
MMAA	ENST00000649156.2 link	c.-68C>T		5_prime_UTR_variant	Exon 1 of 7		NM_172250.3	ENSP00000497008.1		Q8IVH4

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

Data not reliable, filtered out with message: AC0

AF:

0.00

AC:

AN:

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

African (AFR)

AF:

0.00

AC:

AN:

American (AMR)

AC:

AN:

Ashkenazi Jewish (ASJ)

AC:

AN:

East Asian (EAS)

AF:

0.00

AC:

AN:

South Asian (SAS)

AF:

0.00

AC:

AN:

European-Finnish (FIN)

AF:

0.00

AC:

AN:

Middle Eastern (MID)

AF:

0.00

AC:

AN:

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

Other (OTH)

AF:

0.00

AC:

AN:

GnomAD4 genome

Cov.:

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.0000227

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Methylmalonic aciduria, cblA type

Uncertain:1

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.81

CADD

Benign

9.4

(source)

DANN

Benign

0.93

PhyloP100

-4.4

PromoterAI

-0.052

Neutral

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Benign

0.00044

dbscSNV1_RF

Benign

0.046

SpliceAI score (max)

0.30

Details are displayed if max score is > 0.2

DS_DG_spliceai

0.30

Position offset: -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

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over