NM_000254.3:c.2640_2642delAAT

Variant names:

• chr1-236880798-GTAA-G
• rs797044443
• NM_000254.3:c.2640_2642delAAT

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PM4_Supporting

The NM_000254.3(MTR):​c.2640_2642delAAT​(p.Ile881del) variant causes a disruptive inframe deletion change. The variant allele was found at a frequency of 0.00000991 in 1,614,070 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000096 (0 hom.)
• Consequence: MTR NM_000254.3 disruptive_inframe_deletion
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts P:1 U:2
• Conservation: PhyloP100: 4.43

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 Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM4: Nonframeshift variant in NON repetitive region in NM_000254.3. Strenght limited to Supporting due to length of the change: 1aa.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MTR	NM_000254.3	c.2640_2642delAAT	p.Ile881del	disruptive_inframe_deletion	Exon 25 of 33	ENST00000366577.10	NP_000245.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MTR	ENST00000366577.10	c.2640_2642delAAT	p.Ile881del	disruptive_inframe_deletion	Exon 25 of 33	1	NM_000254.3	ENSP00000355536.5
MTR	ENST00000366576.3	c.1302_1304delAAT	p.Ile435del	disruptive_inframe_deletion	Exon 12 of 20	1		ENSP00000355535.3

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152190 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000483

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: 0.00

GnomAD3 exomes AF: 0.00000795 AC: 2 AN: 251486 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135916

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 SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000176

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000958 AC: 14 AN: 1461880 Hom.: 0 AF XY: 0.0000151 AC XY: 11 AN XY: 727244

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: 0.0000126

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152190 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74348

Gnomad4 AFR AF: 0.0000483

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: 0.00

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Methylcobalamin deficiency type cblG Pathogenic:1 Uncertain:1

Sep 06, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant, c.2640_2642del, results in the deletion of 1 amino acid(s) of the MTR protein (p.Ile881del), but otherwise preserves the integrity of the reading frame. This variant is present in population databases (rs765481871, gnomAD 0.004%). This variant has been observed in individual(s) with homocystinuria, cblG type (PMID: 8968736). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 14279). Experimental studies and prediction algorithms are not available or were not evaluated, and the functional significance of this variant is currently unknown. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Dec 01, 1996

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Methylcobalamin deficiency type cblG;C1866558:Neural tube defects, folate-sensitive Uncertain:1

Jul 06, 2021

Fulgent Genetics, Fulgent Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs797044443; hg19: chr1-237044098;