rs777102890

Positions:

• chr5-1279286-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP3

The NM_198253.3(TERT):​c.2130+5G>A variant causes a splice donor 5th base, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000141 in 1,421,098 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: TERT NM_198253.3 splice_donor_5th_base, intron
• Scores: Splicing: ADA: 0.9992
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 1.23

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 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TERT	NM_198253.3	c.2130+5G>A		splice_donor_5th_base_variant, intron_variant		ENST00000310581.10	NP_937983.2
TERT	NM_001193376.3	c.2130+5G>A		splice_donor_5th_base_variant, intron_variant			NP_001180305.1
TERT	NR_149162.3	n.2209+5G>A		splice_donor_5th_base_variant, intron_variant, non_coding_transcript_variant
TERT	NR_149163.3	n.2209+5G>A		splice_donor_5th_base_variant, intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TERT	ENST00000310581.10	c.2130+5G>A		splice_donor_5th_base_variant, intron_variant		1	NM_198253.3	ENSP00000309572	P2

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome AF: 0.00000141 AC: 2 AN: 1421098 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 703270

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: 0.00000183

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 34

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

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

Jan 19, 2021

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. Nucleotide substitutions within the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site, but this prediction has not been confirmed by published transcriptional studies. This variant has not been reported in the literature in individuals with TERT-related disease. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the ExAC database. This sequence change falls in intron 5 of the TERT gene. It does not directly change the encoded amino acid sequence of the TERT protein, but it affects a nucleotide within the consensus splice site of the intron. -

Dyskeratosis congenita Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Molecular Genetics, Royal Melbourne Hospital

Mar 30, 2023

This sequence change falls in the splice region of the donor site of intron 5 of TERT. The variant is absent in a large population cohort (gnomAD v2.1 and v3.1), and has been classified as a variant of uncertain significance (ClinVar). The nucleotide is moderately conserved (100 vertebrates, UCSC), and multiple lines of computational evidence predict an impact on splicing (SpliceAI, MaxEntScan, NNSplice). Based on the classification scheme RMH Modified ACMG Guidelines v1.3.1, this variant is classified as a VARIANT OF UNCERTAIN SIGNIFICANCE. Following criteria are met: PM2_Supporting, PP3. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.77
CADD	Uncertain	24
DANN	Benign	0.58
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.75
SpliceAI score (max)		0.55		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.55		Position offset: -14

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

Publications

LitVar

Other links and lift over

dbSNP: rs777102890; hg19: chr5-1279401;