MMAB p.Cys4Cys

Variant names:

• chr12-109573468-C-C
• NM_052845.4:c.

Your query was ambiguous. Multiple possible variants found:

• chr12-109573469--
• chr12-109573469-G-A

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_052845.4(MMAB):​c. variant causes a exon region change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency: Genomes: not found (cov: 33)
• Consequence: MMAB NM_052845.4 exon_region
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.389
• 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]

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: Labcorp Genetics (formerly Invitae), G2P
• hyperimmunoglobulinemia D with periodic fever

  Inheritance: AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: G2P, Orphanet
• mevalonate kinase deficiency

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• mevalonic aciduria

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Orphanet, Labcorp Genetics (formerly Invitae)
• disseminated superficial actinic porokeratosis

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• porokeratosis of Mibelli

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

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.		exon_region	Exon 1 of 9	NP_443077.1	Q96EY8
	MMAB	NR_038118.2		n.		exon_region	Exon 1 of 10

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MMAB	ENST00000545712.7	TSL:1 MANE Select	c.		exon_region	Exon 1 of 9	ENSP00000445920.1	Q96EY8
	MVK	ENST00000546277.6	TSL:5	c.		exon_region	Exon 1 of 11	ENSP00000438153.2	Q03426
	MVK	ENST00000878305.1		c.		exon_region	Exon 1 of 10	ENSP00000548364.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		0.39

Splicing

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: chr12-110011273;