rs955468279

Variant names:

• chr1-45508910-T-C
• rs955468279
• NM_015506.3:c.544T>C

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PM1 PM2 PP2 PP3_Strong PP5

The NM_015506.3(MMACHC):​c.544T>C​(p.Cys182Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000821 in 1,461,886 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 Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. C182Y) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000082 (0 hom.)
• Consequence: MMACHC NM_015506.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:3
• Conservation: PhyloP100: 7.52
• Publications: 0 publications found

Genes affected

MMACHC (HGNC:24525): (metabolism of cobalamin associated C) The exact function of the protein encoded by this gene is not known, however, its C-terminal region shows similarity to TonB, a bacterial protein involved in energy transduction for cobalamin (vitamin B12) uptake. Hence, it is postulated that this protein may have a role in the binding and intracellular trafficking of cobalamin. Mutations in this gene are associated with methylmalonic aciduria and homocystinuria type cblC. [provided by RefSeq, Oct 2009]

MMACHC Gene-Disease associations (from GenCC):

• methylmalonic aciduria and homocystinuria type cblC

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

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 6 uncertain in NM_015506.3
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 28 curated pathogenic missense variants (we use a threshold of 10). The gene has 7 curated benign missense variants. Gene score misZ: -1.0759 (below the threshold of 3.09). Trascript score misZ: -0.13772 (below the threshold of 3.09). GenCC associations: The gene is linked to methylmalonic aciduria and homocystinuria type cblC.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.957
• PP5: Variant 1-45508910-T-C is Pathogenic according to our data. Variant chr1-45508910-T-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 551269.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_015506.3. 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
	MMACHC	NM_015506.3	MANE Select	c.544T>C	p.Cys182Arg	missense	Exon 4 of 4	NP_056321.2	Q9Y4U1
	MMACHC	NM_001330540.2		c.373T>C	p.Cys125Arg	missense	Exon 4 of 4	NP_001317469.1	A0A0C4DGU2

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MMACHC	ENST00000401061.9	TSL:2 MANE Select	c.544T>C	p.Cys182Arg	missense	Exon 4 of 4	ENSP00000383840.4	Q9Y4U1
	MMACHC	ENST00000616135.1	TSL:2	c.373T>C	p.Cys125Arg	missense	Exon 4 of 5	ENSP00000478859.1	A0A0C4DGU2
	MMACHC	ENST00000933807.1		c.349T>C	p.Cys117Arg	missense	Exon 3 of 3	ENSP00000603866.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000401 AC: 1 AN: 249556 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000883

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000821 AC: 12 AN: 1461886 Hom.: 0 Cov.: 32 AF XY: 0.00000825 AC XY: 6 AN XY: 727244

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.0000224 AC: 1 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.000173 AC: 1 AN: 5766

European-Non Finnish (NFE) AF: 0.00000540 AC: 6 AN: 1112008

Other (OTH) AF: 0.0000662 AC: 4 AN: 60394

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000756

ClinVar

ClinVar submissions

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
1	3	-	Cobalamin C disease (4)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.62
BayesDel_addAF	Pathogenic	0.52	D
BayesDel_noAF	Pathogenic	0.50
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.86	D
Eigen	Pathogenic	0.75
Eigen_PC	Pathogenic	0.75
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Benign	0.69	T
M_CAP	Pathogenic	0.32	D
MetaRNN	Pathogenic	0.96	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Uncertain	2.8	M
PhyloP100		7.5
PrimateAI	Uncertain	0.78	T
PROVEAN	Pathogenic	-6.4	D
REVEL	Pathogenic	0.94
Sift	Benign	0.11	T
Sift4G	Uncertain	0.0030	D
Polyphen		1.0	D
Vest4		0.88
MutPred		0.86		Gain of disorder (P = 0.0031)
MVP		0.95
MPC		0.074
ClinPred		0.97	D
GERP RS		5.7
Varity_R		0.93
gMVP		0.97
Mutation Taster		=4/96	disease causing

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

Other links and lift over

dbSNP: rs955468279; hg19: chr1-45974582;