12-109568772-A-T

Variant names:

• chr12-109568772-A-T
• NM_052845.4:c.288T>A
• MMAB p.Ile96Ile

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 2P and 3B. PM2 BP4_Moderate BP7

The NM_052845.4(MMAB):​c.288T>A​(p.Ile96Ile) variant causes a splice region, synonymous 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. 3/3 splice prediction tools predict no significant impact on normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. I96I) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: MMAB NM_052845.4 splice_region, synonymous
• Scores: Splicing: ADA: 0.00001678
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.266
• Publications: 0 publications found

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 Gene-Disease associations (from GenCC):

• methylmalonic acidemia

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• methylmalonic aciduria, cblB type

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Myriad Women's Health, Orphanet, ClinGen, G2P

ACMG classification

Our verdict: Likely_benign. The variant received -1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.39).
• BP7: Synonymous conserved (PhyloP=0.266 with no splicing effect.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_052845.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MMAB	NM_052845.4	MANE Select	c.288T>A	p.Ile96Ile	splice_region synonymous	Exon 3 of 9	NP_443077.1	Q96EY8
	MMAB	NR_038118.2		n.312T>A		splice_region non_coding_transcript_exon	Exon 3 of 10

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MMAB	ENST00000545712.7	TSL:1 MANE Select	c.288T>A	p.Ile96Ile	splice_region synonymous	Exon 3 of 9	ENSP00000445920.1	Q96EY8
	MMAB	ENST00000878519.1		c.288T>A	p.Ile96Ile	splice_region synonymous	Exon 3 of 10	ENSP00000548578.1
	MMAB	ENST00000878520.1		c.288T>A	p.Ile96Ile	splice_region synonymous	Exon 3 of 8	ENSP00000548579.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.39
CADD	Benign	6.9
DANN	Benign	0.76
PhyloP100		0.27
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.000017
dbscSNV1_RF	Benign	0.0
SpliceAI score (max)		0.090		Details are displayed if max score is > 0.2

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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

hg19: chr12-110006577;