chr1-236795703-CAT-C

Variant names:

• chr1-236795703-CAT-C
• rs1367402633
• NM_000254.3:c.1_2delAT

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_000254.3(MTR):​c.1_2delAT​(p.Met1fs) variant causes a frameshift, start lost change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000248 in 1,614,040 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: MTR NM_000254.3 frameshift, start_lost
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: -0.278

Genes affected

MTR (HGNC:7468): (5-methyltetrahydrofolate-homocysteine methyltransferase) This gene encodes the 5-methyltetrahydrofolate-homocysteine methyltransferase. This enzyme, also known as cobalamin-dependent methionine synthase, catalyzes the final step in methionine biosynthesis. Mutations in MTR have been identified as the underlying cause of methylcobalamin deficiency complementation group G. Alternatively spliced transcript variants encoding distinct isoforms have been found for this gene. [provided by RefSeq, May 2014]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 52 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 1-236795703-CAT-C is Pathogenic according to our data. Variant chr1-236795703-CAT-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 452311.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MTR	NM_000254.3	c.1_2delAT	p.Met1fs	frameshift_variant, start_lost	Exon 1 of 33	ENST00000366577.10	NP_000245.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MTR	ENST00000366577.10	c.1_2delAT	p.Met1fs	frameshift_variant, start_lost	Exon 1 of 33	1	NM_000254.3	ENSP00000355536.5

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152262 Hom.: 0 Cov.: 33

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: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461778 Hom.: 0 AF XY: 0.00000138 AC XY: 1 AN XY: 727194

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152262 Hom.: 0 Cov.: 33 AF XY: 0.0000134 AC XY: 1 AN XY: 74394

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: 0.0000147

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:1

Oct 11, 2017

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.1_2delAT variant has not been published as a pathogenic variant, nor has it been reported as a benign variant to our knowledge. The c.1_2delAT variant is not observed in large population cohorts (Lek et al., 2016). The c.1_2delAT variant alters the initiator Methionine codon, and the resultant protein would be described as p.Met1?" using a question mark to signify that it is not known if the loss of Met1 means that all protein translation is completely prevented or if an abnormal protein is produced using an alternate Met. In summary, we interpret this variant as likely pathogenic." -

Computational scores

Source: dbNSFP v4.3

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: rs1367402633; hg19: chr1-236959003;