rs864309727

Positions:

• chr4-145639497-C-T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_172250.3(MMAA):​c.358C>T​(p.Gln120*) variant causes a stop gained change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,726 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: MMAA NM_172250.3 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:2 O:1
• Conservation: PhyloP100: 7.50

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 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 18 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 4-145639497-C-T is Pathogenic according to our data. Variant chr4-145639497-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 218972.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MMAA	NM_172250.3	c.358C>T	p.Gln120*	stop_gained	2/7	ENST00000649156.2	NP_758454.1
MMAA	NM_001375644.1	c.358C>T	p.Gln120*	stop_gained	2/7		NP_001362573.1
MMAA	XM_011531684.4	c.358C>T	p.Gln120*	stop_gained	2/7		XP_011529986.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MMAA	ENST00000649156.2	c.358C>T	p.Gln120*	stop_gained	2/7		NM_172250.3	ENSP00000497008.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461726 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727162

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Methylmalonic aciduria, cblA type Pathogenic:2 Other:1

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Aug 08, 2023	For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 218972). This sequence change creates a premature translational stop signal (p.Gln120*) 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 aciduria cobalamin A type (PMID: 15781192, 20549364). -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Apr 10, 2023	- -
not provided, no classification provided	literature only	GeneReviews	-	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.65
CADD	Pathogenic	37
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Pathogenic	0.98	D
Vest4		0.90, 0.89
GERP RS		5.4

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

LitVar

Other links and lift over

dbSNP: rs864309727; hg19: chr4-146560649;