chr22-19877126-CG-C

Variant names:

• chr22-19877126-CG-C
• NM_006440.5:c.1553delC

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_006440.5(TXNRD2):​c.1553delC​(p.Thr518ArgfsTer2) variant causes a frameshift change. The variant allele was found at a frequency of 0.00000069 in 1,449,078 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. T518T) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: TXNRD2 NM_006440.5 frameshift
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 5.08
• Publications: 0 publications found

Genes affected

TXNRD2 (HGNC:18155): (thioredoxin reductase 2) The protein encoded by this gene belongs to the pyridine nucleotide-disulfide oxidoreductase family, and is a member of the thioredoxin (Trx) system. Three thioredoxin reductase (TrxR) isozymes are found in mammals. TrxRs are selenocysteine-containing flavoenzymes, which reduce thioredoxins, as well as other substrates, and play a key role in redox homoeostasis. This gene encodes a mitochondrial form important for scavenging reactive oxygen species in mitochondria. It functions as a homodimer containing FAD, and selenocysteine (Sec) at the active site. Sec is encoded by UGA codon that normally signals translation termination. The 3' UTRs of selenoprotein mRNAs contain a conserved stem-loop structure, the Sec insertion sequence (SECIS) element, which is necessary for the recognition of UGA as a Sec codon rather than as a stop signal. Alternatively spliced transcript variants encoding different isoforms, including a few localized in the cytosol and some lacking the C-terminal Sec residue, have been found for this gene. [provided by RefSeq, Jun 2017]

TXNRD2 Gene-Disease associations (from GenCC):

• familial isolated dilated cardiomyopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• familial glucocorticoid deficiency

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• dilated cardiomyopathy

  Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics
• glucocorticoid deficiency 5

  Inheritance: Unknown Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TXNRD2	NM_006440.5	c.1553delC	p.Thr518ArgfsTer2	frameshift_variant	Exon 17 of 18	ENST00000400521.7	NP_006431.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TXNRD2	ENST00000400521.7	c.1553delC	p.Thr518ArgfsTer2	frameshift_variant	Exon 17 of 18	1	NM_006440.5	ENSP00000383365.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.90e-7 AC: 1 AN: 1449078 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 718442

African (AFR) AF: 0.00 AC: 0 AN: 33264

American (AMR) AF: 0.00 AC: 0 AN: 44478

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26004

East Asian (EAS) AF: 0.00 AC: 0 AN: 39312

South Asian (SAS) AF: 0.00 AC: 0 AN: 85970

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52360

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5724

European-Non Finnish (NFE) AF: 9.07e-7 AC: 1 AN: 1102290

Other (OTH) AF: 0.00 AC: 0 AN: 59676

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Dec 07, 2022

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Frameshift variant predicted to result in protein truncation as the last 7 amino acids are replaced with 1 different amino acids, although loss-of-function variants have not been reported downstream of this position in the protein; Not observed at significant frequency in large population cohorts (gnomAD); Has not been previously published as pathogenic or benign to our knowledge -

Primary dilated cardiomyopathy Uncertain:1

Oct 29, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Thr518Argfs*2) in the TXNRD2 gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 7amino acid(s) of the TXNRD2 protein. This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TXNRD2-related conditions. ClinVar contains an entry for this variant (Variation ID: 2504940). 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
PhyloP100		5.1

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.12		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

hg19: chr22-19864649;