rs1801198

Positions:

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PM2BP4_Strong

The NM_000355.4(TCN2):c.776G>A(p.Arg259His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000229 in 1,613,860 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R259P) has been classified as Benign.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000025 ( 0 hom. )

Consequence

TCN2
NM_000355.4 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 0.373

Variant links:

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]

TCN2 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

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 (MetaRNN=0.059171706).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TCN2	NM_000355.4 linkuse as main transcript	c.776G>A	p.Arg259His	missense_variant	6/9	ENST00000215838.8	NP_000346.2
TCN2	NM_001184726.2 linkuse as main transcript	c.695G>A	p.Arg232His	missense_variant	6/9		NP_001171655.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TCN2	ENST00000215838.8 linkuse as main transcript	c.776G>A	p.Arg259His	missense_variant	6/9	1	NM_000355.4	ENSP00000215838	P2	P20062-1

Frequencies

GnomAD3 genomes

AF:

0.00000658

AC:

AN:

151952

Hom.:

Cov.:

show subpopulations

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:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000558

AC:

AN:

251026

Hom.:

AF XY:

0.0000663

AC XY:

AN XY:

135704

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000544

Gnomad SAS exome

AF:

0.000425

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000246

AC:

AN:

1461790

Hom.:

Cov.:

AF XY:

0.0000261

AC XY:

AN XY:

727178

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.0000756

Gnomad4 SAS exome

AF:

0.000325

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

8.99e-7

Gnomad4 OTH exome

AF:

0.0000497

GnomAD4 genome

AF:

0.00000658

AC:

AN:

152070

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74316

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.000208

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

ExAC

AF:

0.0000659

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Transcobalamin II deficiency

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 02, 2021

This sequence change replaces arginine, which is basic and polar, with histidine, which is basic and polar, at codon 259 of the TCN2 protein (p.Arg259His). This variant is present in population databases (rs1801198, gnomAD 0.04%). This variant has not been reported in the literature in individuals affected with TCN2-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0". The histidine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect protein function. 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. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.071

BayesDel_addAF

Benign

-0.46

BayesDel_noAF

Benign

-0.57

CADD

Benign

DANN

Uncertain

0.99

DEOGEN2

Benign

0.036

T;T;T;.

Eigen

Benign

-0.74

Eigen_PC

Benign

-0.79

FATHMM_MKL

Benign

0.32

LIST_S2

Benign

0.59

T;T;T;T

M_CAP

Benign

0.012

MetaRNN

Benign

0.059

T;T;T;T

MetaSVM

Benign

-1.0

MutationAssessor

Benign

0.90

L;.;.;.

MutationTaster

Benign

1.0

N;N;N

PrimateAI

Benign

0.29

PROVEAN

Benign

0.98

N;.;N;N

REVEL

Benign

0.084

Sift

Benign

0.075

T;.;T;T

Sift4G

Benign

0.11

T;T;T;T

Polyphen

0.58

P;.;P;.

Vest4

0.063

MutPred

0.31

Loss of methylation at R259 (P = 0.0254);.;.;.;

MVP

0.38

MPC

0.014

ClinPred

0.064

GERP RS

4.1

Varity_R

0.071

gMVP

0.28

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over