chr5-1294135-C-G

Position:

• chr5-1294135-C-G

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_198253.3(TERT):​c.751G>C​(p.Val251Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000007 in 1,429,202 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 (★★).

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 7.0e-7 (0 hom.)
• Consequence: TERT NM_198253.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: -2.39

Genes affected

TERT (HGNC:11730): (telomerase reverse transcriptase) Telomerase is a ribonucleoprotein polymerase that maintains telomere ends by addition of the telomere repeat TTAGGG. The enzyme consists of a protein component with reverse transcriptase activity, encoded by this gene, and an RNA component which serves as a template for the telomere repeat. Telomerase expression plays a role in cellular senescence, as it is normally repressed in postnatal somatic cells resulting in progressive shortening of telomeres. Deregulation of telomerase expression in somatic cells may be involved in oncogenesis. Studies in mouse suggest that telomerase also participates in chromosomal repair, since de novo synthesis of telomere repeats may occur at double-stranded breaks. Alternatively spliced variants encoding different isoforms of telomerase reverse transcriptase have been identified; the full-length sequence of some variants has not been determined. Alternative splicing at this locus is thought to be one mechanism of regulation of telomerase activity. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.085172296).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TERT	NM_198253.3	c.751G>C	p.Val251Leu	missense_variant	2/16	ENST00000310581.10	NP_937983.2
TERT	NM_001193376.3	c.751G>C	p.Val251Leu	missense_variant	2/15		NP_001180305.1
TERT	NR_149162.3	n.830G>C		non_coding_transcript_exon_variant	2/13
TERT	NR_149163.3	n.830G>C		non_coding_transcript_exon_variant	2/13

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TERT	ENST00000310581.10	c.751G>C	p.Val251Leu	missense_variant	2/16	1	NM_198253.3	ENSP00000309572	P2
TERT	ENST00000334602.10	c.751G>C	p.Val251Leu	missense_variant	2/15	1		ENSP00000334346	A2
TERT	ENST00000460137.6	c.751G>C	p.Val251Leu	missense_variant, NMD_transcript_variant	2/13	1		ENSP00000425003
TERT	ENST00000656021.1	c.751G>C	p.Val251Leu	missense_variant, NMD_transcript_variant	2/17			ENSP00000499759

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome AF: 7.00e-7 AC: 1 AN: 1429202 Hom.: 0 Cov.: 35 AF XY: 0.00 AC XY: 0 AN XY: 709264

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.11e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 34

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Idiopathic Pulmonary Fibrosis;C3151443:Dyskeratosis congenita, autosomal dominant 2 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 28, 2022

This sequence change replaces valine, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 251 of the TERT protein (p.Val251Leu). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TERT-related conditions. ClinVar contains an entry for this variant (Variation ID: 953128). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt TERT 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. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Jun 01, 2022

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant does not alter protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

Dyskeratosis congenita Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Apr 19, 2022

The p.V251L variant (also known as c.751G>C), located in coding exon 2 of the TERT gene, results from a G to C substitution at nucleotide position 751. The valine at codon 251 is replaced by leucine, an amino acid with highly similar properties. This amino acid position is conserved. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.086
BayesDel_addAF	Benign	-0.084	T
BayesDel_noAF	Benign	-0.36
CADD	Benign	0.17
DANN	Benign	0.38
DEOGEN2	Benign	0.32	T;.
Eigen	Benign	-1.5
Eigen_PC	Benign	-1.6
FATHMM_MKL	Benign	0.014	N
LIST_S2	Benign	0.63	T;T
M_CAP	Pathogenic	0.39	D
MetaRNN	Benign	0.085	T;T
MetaSVM	Uncertain	-0.026	T
MutationAssessor	Benign	0.0	N;N
MutationTaster	Benign	1.0	N;N;N;N
PrimateAI	Uncertain	0.60	T
PROVEAN	Benign	-0.31	N;N
REVEL	Benign	0.15
Sift	Benign	0.75	T;T
Sift4G	Benign	0.65	T;T
Polyphen		0.0010	B;B
Vest4		0.083
MutPred		0.23		Loss of MoRF binding (P = 0.102);Loss of MoRF binding (P = 0.102);
MVP		0.60
MPC		1.0
ClinPred		0.026	T
GERP RS		-4.5
Varity_R		0.065
gMVP		0.57

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

LitVar

Other links and lift over

dbSNP: rs776569822; hg19: chr5-1294250;