1-45500334-T-A

Variant names:

• chr1-45500334-T-A
• rs574983400
• NM_015506.3:c.2T>A

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PS1_Moderate PM2

The NM_015506.3(MMACHC):​c.2T>A​(p.Met1?) variant causes a start lost change. The variant allele was found at a frequency of 0.00000657 in 152,218 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.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: MMACHC NM_015506.3 start_lost
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 4.51

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]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Start lost variant, next in-frame start position is after 19 pathogenic variants. Next in-frame start position is after 58 codons. Genomic position: 45507446. Lost 0.203 part of the original CDS.
• PS1: Another start lost variant in NM_015506.3 (MMACHC) was described as [Pathogenic] in ClinVar as 203823
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MMACHC	NM_015506.3	c.2T>A	p.Met1?	start_lost	Exon 1 of 4	ENST00000401061.9	NP_056321.2
MMACHC	NM_001330540.2	c.-221T>A		5_prime_UTR_variant	Exon 1 of 4		NP_001317469.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MMACHC	ENST00000401061.9	c.2T>A	p.Met1?	start_lost	Exon 1 of 4	2	NM_015506.3	ENSP00000383840.4
MMACHC	ENST00000616135.1	c.-170T>A		upstream_gene_variant		2		ENSP00000478859.1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152218 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

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: 0.000478

GnomAD4 exome Cov.: 30

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152218 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74364

Gnomad4 AFR AF: 0.00

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: 0.000478

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.60	D
BayesDel_noAF	Pathogenic	0.65
CADD	Uncertain	25
DANN	Uncertain	0.98
DEOGEN2	Benign	0.088	T
Eigen	Uncertain	0.60
Eigen_PC	Uncertain	0.60
FATHMM_MKL	Uncertain	0.89	D
LIST_S2	Uncertain	0.90	D
M_CAP	Pathogenic	0.95	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	1.0	D
PROVEAN	Benign	-1.2	N
REVEL	Pathogenic	0.76
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		0.98	D
Vest4		0.94
MutPred		0.98		Loss of ubiquitination at K4 (P = 0.0355);
MVP		0.99
ClinPred		0.99	D
GERP RS		5.8
Varity_R		0.99
gMVP		0.75

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: rs574983400; hg19: chr1-45966006;