chr1-45507455-C-G

Variant names:

• chr1-45507455-C-G
• rs200483477
• NM_015506.3:c.181C>G

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 7P and 2B. PM1 PM2 PM5 PP2 BP4_Moderate

The NM_015506.3(MMACHC):​c.181C>G​(p.Arg61Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,874 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/22 in silico tools predict a benign 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. R61W) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: MMACHC NM_015506.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 1.24
• 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: Labcorp Genetics (formerly Invitae), Ambry Genetics, Myriad Women’s Health, ClinGen, G2P, Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 5 ACMG points.

• PM1: In a chain Cyanocobalamin reductase / alkylcobalamin dealkylase (size 281) in uniprot entity MMAC_HUMAN there are 42 pathogenic changes around while only 16 benign (72%) in NM_015506.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr1-45507456-G-C is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 854802.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• 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.
• BP4: Computational evidence support a benign effect (MetaRNN=0.25217056).

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

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MMACHC	NM_015506.3	MANE Select	c.181C>G	p.Arg61Gly	missense	Exon 2 of 4	NP_056321.2
	MMACHC	NM_001330540.2		c.10C>G	p.Arg4Gly	missense	Exon 2 of 4	NP_001317469.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MMACHC	ENST00000401061.9	TSL:2 MANE Select	c.181C>G	p.Arg61Gly	missense	Exon 2 of 4	ENSP00000383840.4
	MMACHC	ENST00000616135.1	TSL:2	c.10C>G	p.Arg4Gly	missense	Exon 2 of 5	ENSP00000478859.1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461874 Hom.: 0 Cov.: 32 AF XY: 0.00000275 AC XY: 2 AN XY: 727236

African (AFR) AF: 0.00 AC: 0 AN: 33476

American (AMR) AF: 0.00 AC: 0 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: 86254

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53418

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000360 AC: 4 AN: 1112004

Other (OTH) AF: 0.00 AC: 0 AN: 60394

GnomAD4 genome Cov.: 31

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Uncertain	0.099	D
BayesDel_noAF	Benign	-0.10
CADD	Benign	22
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.76	D
Eigen	Benign	-0.25
Eigen_PC	Benign	-0.14
FATHMM_MKL	Benign	0.48	N
LIST_S2	Benign	0.81	T
M_CAP	Benign	0.039	D
MetaRNN	Benign	0.25	T
MetaSVM	Uncertain	0.27	D
MutationAssessor	Uncertain	2.5	M
PhyloP100		1.2
PrimateAI	Benign	0.20	T
PROVEAN	Uncertain	-3.2	D
REVEL	Benign	0.25
Sift	Benign	0.12	T
Sift4G	Benign	0.084	T
Polyphen		0.083	B
Vest4		0.31
MutPred		0.28		Loss of methylation at K64 (P = 0.0475)
MVP		0.91
MPC		0.014
ClinPred		0.56	D
GERP RS		4.4
Varity_R		0.33
gMVP		0.43
Mutation Taster		=73/27	polymorphism

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: rs200483477; hg19: chr1-45973127;