22-30607141-G-A

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The ENST00000450638.5(TCN2):c.-367G>A variant causes a 5 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000134 in 633,786 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: 𝑓 0.000033 (0 hom., cov: 30)
  • Exomes 𝑓: 0.00017 (0 hom.)
• Consequence: TCN2 ENST00000450638.5 5_prime_UTR
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -0.109

Genes affected

TCN2 (HGNC:11653): (transcobalamin 2) This gene encodes a member of the vitamin B12-binding protein family. This family of proteins, alternatively referred to as R binders, is expressed in various tissues and secretions. This plasma protein binds cobalamin and mediates the transport of cobalamin into cells. This protein and other mammalian cobalamin-binding proteins, such as transcobalamin I and gastric intrisic factor, may have evolved by duplication of a common ancestral gene. Alternative splicing results in multiple transcript variants.[provided by RefSeq, May 2010]

ACMG classification

Verdict is Likely_benign. Variant got -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.8).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TCN2	NM_000355.4			upstream_gene_variant		ENST00000215838.8
TCN2	NM_001184726.2			upstream_gene_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TCN2	ENST00000215838.8			upstream_gene_variant		1	NM_000355.4	P2

Frequencies

GnomAD3 genomes AF: 0.0000330 AC: 5 AN: 151346 Hom.: 0 Cov.: 30

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000660

Gnomad ASJ AF: 0.000865

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000209

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.000166 AC: 80 AN: 482440 Hom.: 0 Cov.: 6 AF XY: 0.000172 AC XY: 44 AN XY: 255190

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.000146

Gnomad4 ASJ exome AF: 0.00241

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.000329

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000588

Gnomad4 OTH exome AF: 0.000189

GnomAD4 genome AF: 0.0000330 AC: 5 AN: 151346 Hom.: 0 Cov.: 30 AF XY: 0.0000135 AC XY: 1 AN XY: 73880

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.0000660

Gnomad4 ASJ AF: 0.000865

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000209

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000540 Hom.: 0

Bravo AF: 0.0000340

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Transcobalamin II deficiency Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.80
Cadd	Benign	5.0
Dann	Benign	0.70

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: rs886057394; hg19: chr22-31003128;