rs773059864

Positions:

• chr12-109561067-C-A
• chr12-109561067-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2 PM5 PP3_Strong

The NM_052845.4(MMAB):​c.557G>T​(p.Arg186Leu) variant causes a missense change. The variant allele was found at a frequency of 0.00000658 in 151,946 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic 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. R186W) has been classified as Pathogenic.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 30)
• Consequence: MMAB NM_052845.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 5.67

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 (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 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 chr12-109561068-G-A is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.996

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
MMAB	NM_052845.4	c.557G>T	p.Arg186Leu	missense_variant	7/9	ENST00000545712.7	NP_443077.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
MMAB	ENST00000545712.7	c.557G>T	p.Arg186Leu	missense_variant	7/9	1	NM_052845.4	ENSP00000445920.1

Frequencies

GnomAD3 genomes AF: 0.00000658 AC: 1 AN: 151946 Hom.: 0 Cov.: 30

Gnomad AFR AF: 0.0000242

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 35

GnomAD4 genome AF: 0.00000658 AC: 1 AN: 151946 Hom.: 0 Cov.: 30 AF XY: 0.0000135 AC XY: 1 AN XY: 74194

Gnomad4 AFR AF: 0.0000242

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.86
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.57
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.86	D;.
Eigen	Pathogenic	0.86
Eigen_PC	Pathogenic	0.68
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Pathogenic	0.98	D;D
M_CAP	Pathogenic	0.91	D
MetaRNN	Pathogenic	1.0	D;D
MetaSVM	Pathogenic	0.98	D
MutationAssessor	Pathogenic	4.8	H;.
PrimateAI	Uncertain	0.67	T
PROVEAN	Pathogenic	-6.5	D;.
REVEL	Pathogenic	0.96
Sift	Pathogenic	0.0	D;.
Sift4G	Pathogenic	0.0	D;D
Polyphen		1.0	D;.
Vest4		0.98
MutPred		0.96		Loss of MoRF binding (P = 0.005);.;
MVP		0.99
MPC		0.94
ClinPred		1.0	D
GERP RS		4.9
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.98
gMVP		0.98

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: rs773059864; hg19: chr12-109998872;