Genetic Variant TCN2:p.Leu293Val (chr22-30615724-C-G) – ACMG Classification: Uncertain_significance (3 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PM2PP3

The NM_000355.4(TCN2):c.877C>G(p.Leu293Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,894 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. Synonymous variant affecting the same amino acid position (i.e. L293L) has been classified as Likely benign.

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 0.0000014 ( 0 hom. )

Consequence

TCN2
NM_000355.4 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 1.49

Publications

0 publications found

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 Gene-Disease associations (from GenCC):

transcobalamin II deficiency
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Ambry Genetics, Labcorp Genetics (formerly Invitae), Orphanet

TCN2 links:

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ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PP3

MetaRNN computational evidence supports a deleterious effect, 0.838

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TCN2	NM_000355.4 link	c.877C>G	p.Leu293Val	missense_variant	Exon 6 of 9	ENST00000215838.8	NP_000346.2	P20062-1
TCN2	NM_001184726.2 link	c.796C>G	p.Leu266Val	missense_variant	Exon 6 of 9		NP_001171655.1	P20062-2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TCN2	ENST00000215838.8 link	c.877C>G	p.Leu293Val	missense_variant	Exon 6 of 9	1	NM_000355.4	ENSP00000215838.3		P20062-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

0.00000137

AC:

AN:

1461894

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

727248

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53420

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00000180

AC:

AN:

1112012

Other (OTH)

AF:

0.00

AC:

AN:

60396

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.425

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.34

BayesDel_addAF

Uncertain

0.15

BayesDel_noAF

Uncertain

-0.020

CADD

Benign

(source)

DANN

Uncertain

1.0

DEOGEN2

Benign

0.22

T;T;T;.

Eigen

Uncertain

0.30

Eigen_PC

Uncertain

0.22

FATHMM_MKL

Uncertain

0.95

LIST_S2

Benign

0.79

T;T;T;T

M_CAP

Benign

0.034

MetaRNN

Pathogenic

0.84

D;D;D;D

MetaSVM

Benign

-0.46

MutationAssessor

Pathogenic

3.1

M;.;.;.

PhyloP100

1.5

PrimateAI

Uncertain

0.54

PROVEAN

Uncertain

-2.7

D;.;D;D

REVEL

Uncertain

0.46

Sift

Uncertain

0.0050

D;.;D;D

Sift4G

Uncertain

0.014

D;D;D;D

Polyphen

1.0

D;.;D;.

Vest4

0.64

MutPred

0.86

Loss of helix (P = 0.3949);.;.;.;

MVP

0.64

MPC

0.058

ClinPred

0.97

GERP RS

2.9

Varity_R

0.58

gMVP

0.68

Mutation Taster

=58/42

polymorphism

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over