rs1157135425

chr22-30615770-ACTGT-A

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_000355.4(TCN2):c.927_930del(p.Cys309TrpfsTer50) variant causes a frameshift change. The variant allele was found at a frequency of 0.0000136 in 1,614,030 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★). Synonymous variant affecting the same amino acid position (i.e. D308D) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: 𝑓 0.000020 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000013 (0 hom.)
• Consequence: TCN2 NM_000355.4 frameshift
• Clinical Significance: Pathogenic criteria provided, single submitter P:2 O:1
• Conservation: PhyloP100: 5.59

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 Pathogenic. Variant got 12 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 22-30615770-ACTGT-A is Pathogenic according to our data. Variant chr22-30615770-ACTGT-A is described in ClinVar as [Pathogenic]. Clinvar id is 96.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TCN2	NM_000355.4	c.927_930del	p.Cys309TrpfsTer50	frameshift_variant	6/9	ENST00000215838.8
TCN2	NM_001184726.2	c.846_849del	p.Cys282TrpfsTer50	frameshift_variant	6/9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TCN2	ENST00000215838.8	c.927_930del	p.Cys309TrpfsTer50	frameshift_variant	6/9	1	NM_000355.4	P2

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152144 Hom.: 0 Cov.: 33

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: 0.0000294

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.0000130 AC: 19 AN: 1461886 Hom.: 0 AF XY: 0.0000124 AC XY: 9 AN XY: 727246

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000153

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152144 Hom.: 0 Cov.: 33 AF XY: 0.0000269 AC XY: 2 AN XY: 74328

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000207

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000294

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000151

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

Transcobalamin II deficiency Pathogenic:2 Other:1

not provided, no classification provided	not provided	Inserm U 954, Faculté de Médecine de Nancy	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Dec 31, 2023	This sequence change creates a premature translational stop signal (p.Cys309Trpfs*50) in the TCN2 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in TCN2 are known to be pathogenic (PMID: 7980584, 20352340). This variant is present in population databases (rs796064506, gnomAD 0.007%). This premature translational stop signal has been observed in individual(s) with suspected primary immunodeficiency and/or transcobalamin II deficiency (PMID: 7849710, 32888943). ClinVar contains an entry for this variant (Variation ID: 96). For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, no assertion criteria provided	literature only	OMIM	Jun 01, 2009	- -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs1157135425; hg19: chr22-31011757;