NM_000355.4:c.230A>T

Variant names:

Variant summary

Our verdict is Benign. The variant received -20 ACMG points: 0P and 20B. BP4_StrongBP6_Very_StrongBS1BS2

The NM_000355.4(TCN2):c.230A>T(p.Lys77Met) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00106 in 1,614,076 control chromosomes in the GnomAD database, including 44 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Benign (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. K77R) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.0015 ( 9 hom., cov: 33)

Exomes 𝑓: 0.0010 ( 35 hom. )

Consequence

TCN2
NM_000355.4 missense

Scores

Clinical Significance

Benign criteria provided, multiple submitters, no conflicts B:4

Conservation

PhyloP100: 1.38

Publications

11 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:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Benign. The variant received -20 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.0064339936).

BP6

Variant 22-30611036-A-T is Benign according to our data. Variant chr22-30611036-A-T is described in ClinVar as Benign. ClinVar VariationId is 341190.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

BS1

Variant frequency is greater than expected in population eas. GnomAd4 allele frequency = 0.0015 (229/152250) while in subpopulation EAS AF = 0.0422 (218/5170). AF 95% confidence interval is 0.0376. There are 9 homozygotes in GnomAd4. There are 138 alleles in the male GnomAd4 subpopulation. Median coverage is 33. This position passed quality control check.

BS2

High Homozygotes in GnomAd4 at 9 AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TCN2	NM_000355.4 link	c.230A>T	p.Lys77Met	missense_variant	Exon 2 of 9	ENST00000215838.8	NP_000346.2	P20062-1
TCN2	NM_001184726.2 link	c.230A>T	p.Lys77Met	missense_variant	Exon 2 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.230A>T	p.Lys77Met	missense_variant	Exon 2 of 9	1	NM_000355.4	ENSP00000215838.3		P20062-1

Frequencies

GnomAD3 genomes

AF:

0.00151

AC:

229

AN:

152132

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.0421

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.000118

Gnomad OTH

AF:

0.000478

GnomAD2 exomes

AF:

0.00274

AC:

690

AN:

251400

AF XY:

0.00256

show subpopulations

Gnomad AFR exome

AF:

0.0000615

Gnomad AMR exome

AF:

0.0000867

Gnomad ASJ exome

AF:

0.0000994

Gnomad EAS exome

AF:

0.0364

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000264

Gnomad OTH exome

AF:

0.00130

GnomAD4 exome

AF:

0.00102

AC:

1485

AN:

1461826

Hom.:

Cov.:

AF XY:

0.000943

AC XY:

686

AN XY:

727218

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.0000894

AC:

AN:

44720

Ashkenazi Jewish (ASJ)

AF:

0.000191

AC:

AN:

26120

East Asian (EAS)

AF:

0.0349

AC:

1386

AN:

39700

South Asian (SAS)

AF:

0.0000812

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53414

Middle Eastern (MID)

AF:

0.000173

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.0000369

AC:

AN:

1111970

Other (OTH)

AF:

0.000679

AC:

AN:

60396

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.490

Heterozygous variant carriers

182

272

363

454

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Exome Hom

Variant carriers

120

<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

AF:

0.00150

AC:

229

AN:

152250

Hom.:

Cov.:

AF XY:

0.00185

AC XY:

138

AN XY:

74456

show subpopulations

African (AFR)

AF:

0.0000241

AC:

AN:

41552

American (AMR)

AF:

0.00

AC:

AN:

15284

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.0422

AC:

218

AN:

5170

South Asian (SAS)

AF:

0.000207

AC:

AN:

4822

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10616

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.000118

AC:

AN:

68014

Other (OTH)

AF:

0.000473

AC:

AN:

2114

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.497

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Genome Hom

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

Alfa

AF:

0.00126

Hom.:

Bravo

AF:

0.00426

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000116

AC:

ExAC

AF:

0.00268

AC:

326

Asia WGS

AF:

0.00895

AC:

AN:

3478

EpiCase

AF:

0.0000545

EpiControl

AF:

0.00

ClinVar

Significance: Benign

Submissions summary: Benign:4

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Transcobalamin II deficiency

Benign:2

Feb 01, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

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 and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -

TCN2-related disorder

Benign:1

Nov 03, 2022

PreventionGenetics, part of Exact Sciences

Significance:Benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

This variant is classified as benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications). -

not provided

Benign:1

Breakthrough Genomics, Breakthrough Genomics

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:not provided

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.34

BayesDel_addAF

Benign

-0.42

BayesDel_noAF

Benign

-0.34

CADD

Uncertain

(source)

DANN

Uncertain

0.99

DEOGEN2

Benign

0.090

T;T;T;.

Eigen

Uncertain

0.24

Eigen_PC

Uncertain

0.29

FATHMM_MKL

Uncertain

0.82

LIST_S2

Benign

0.69

T;T;T;T

MetaRNN

Benign

0.0064

T;T;T;T

MetaSVM

Benign

-1.1

MutationAssessor

Uncertain

2.7

M;.;.;M

PhyloP100

1.4

PrimateAI

Benign

0.48

PROVEAN

Uncertain

-2.8

D;.;D;D

REVEL

Benign

0.20

Sift

Benign

0.052

T;.;T;T

Sift4G

Benign

0.18

T;T;T;T

Polyphen

0.73

P;.;P;.

Vest4

0.37

MVP

0.67

MPC

0.025

ClinPred

0.085

GERP RS

5.1

Varity_R

0.38

gMVP

0.54

Mutation Taster

=85/15

polymorphism

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over