9-21971030-C-T

Position:

• chr9-21971030-C-T

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000077.5(CDKN2A):​c.329G>A​(p.Trp110Ter) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: CDKN2A NM_000077.5 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: -0.318

Genes affected

CDKN2A (HGNC:1787): (cyclin dependent kinase inhibitor 2A) This gene generates several transcript variants which differ in their first exons. At least three alternatively spliced variants encoding distinct proteins have been reported, two of which encode structurally related isoforms known to function as inhibitors of CDK4 kinase. The remaining transcript includes an alternate first exon located 20 Kb upstream of the remainder of the gene; this transcript contains an alternate open reading frame (ARF) that specifies a protein which is structurally unrelated to the products of the other variants. This ARF product functions as a stabilizer of the tumor suppressor protein p53 as it can interact with, and sequester, the E3 ubiquitin-protein ligase MDM2, a protein responsible for the degradation of p53. In spite of the structural and functional differences, the CDK inhibitor isoforms and the ARF product encoded by this gene, through the regulatory roles of CDK4 and p53 in cell cycle G1 progression, share a common functionality in cell cycle G1 control. This gene is frequently mutated or deleted in a wide variety of tumors, and is known to be an important tumor suppressor gene. [provided by RefSeq, Sep 2012]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most 50 bp of the penultimate exon, not predicted to undergo nonsense mediated mRNA decay. There are 23 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 9-21971030-C-T is Pathogenic according to our data. Variant chr9-21971030-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 376304.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CDKN2A	NM_000077.5	c.329G>A	p.Trp110Ter	stop_gained	2/3	ENST00000304494.10
CDKN2A	NM_058195.4	c.372G>A	p.Leu124=	synonymous_variant	2/3	ENST00000579755.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CDKN2A	ENST00000304494.10	c.329G>A	p.Trp110Ter	stop_gained	2/3	1	NM_000077.5	P2
CDKN2A	ENST00000579755.2	c.372G>A	p.Leu124=	synonymous_variant	2/3	1	NM_058195.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Neoplasm Pathogenic:1

Likely pathogenic, no assertion criteria provided

literature only

Database of Curated Mutations (DoCM)

Jul 14, 2015

- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Jun 29, 2017

This variant is denoted CDKN2A c.329G>A at the cDNA level and p.Trp110Ter (W110X) at the protein level. The CDKN2A gene encodes the p16 protein, and using an alternate reading frame, the p14ARF protein as well. Although this variant is encoded in both proteins, the effect on the p14ARF protein is the synonymous change Leu124=. However, in regard to p16, the substitution creates a nonsense variant, which changes a Tryptophan to a premature stop codon (TGG>TAG), and is predicted to cause loss of normal protein function through either protein truncation or nonsense-mediated mRNA decay. CDKN2A Trp110Ter has been shown to result in the absence of wild type p16 expression and lead to defective cell cycle arrest (Arap 1997, Krimpenfort 2001). Based on the currently available evidence, CDKN2A Trp110Ter is considered pathogenic. -

Familial melanoma Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jun 16, 2023

The CDKN2A gene encodes two different proteins, p16INK4a and p14ARF, which are translated from alternative transcripts with different open reading frames. Both transcripts have been analyzed. We report either the variant with the higher classification or default to the CDKN2A (p16INK4a) variant. This report therefore includes the details for the CDKN2A (p16INK4a) variant. For these reasons, this variant has been classified as Pathogenic. While the evidence indicates that this variant confers risk of developing CDKN2A (p16INK4a)-associated conditions, its association with risk for developing CDKN2A (p14ARF)-associated conditions is still unclear. ClinVar contains an entry for this variant (Variation ID: 376304). This variant is also known as c.372G>A (Silent) in CDKN2A (p14ARF) transcript. This variant has not been reported in the literature in individuals affected with CDKN2A (p16INK4a)-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Trp110*) in the CDKN2A (p16INK4a) gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in CDKN2A (p16INK4a) are known to be pathogenic (PMID: 15146471, 16905682). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.40	D
BayesDel_noAF	Pathogenic	0.34
CADD	Pathogenic	39
DANN	Uncertain	0.99
Eigen	Pathogenic	0.77
Eigen_PC	Uncertain	0.58
FATHMM_MKL	Benign	0.22	N
MutationTaster	Benign	1.0	A;A;A;A;A;A;A;A;D;D;D;D
Vest4		0.89
GERP RS		5.0

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: rs1057519852; hg19: chr9-21971029; COSMIC: COSV58682976; COSMIC: COSV58682976;