rs121913385

Positions:

• chr9-21971112-G-A
• chr9-21971112-G-C
• chr9-21971112-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM1 PM2

The NM_000077.5(CDKN2A):​c.247C>T​(p.His83Tyr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: CDKN2A NM_000077.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:3
• Conservation: PhyloP100: 9.23

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]

CDKN2A (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM1: In a chain Cyclin-dependent kinase inhibitor 2A (size 155) in uniprot entity CDN2A_HUMAN there are 42 pathogenic changes around while only 12 benign (78%) in NM_000077.5
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CDKN2A	NM_000077.5	c.247C>T	p.His83Tyr	missense_variant	2/3	ENST00000304494.10	NP_000068.1
CDKN2A	NM_058195.4	c.290C>T	p.Ala97Val	missense_variant	2/3	ENST00000579755.2	NP_478102.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CDKN2A	ENST00000304494.10	c.247C>T	p.His83Tyr	missense_variant	2/3	1	NM_000077.5	ENSP00000307101.5
CDKN2A	ENST00000579755.2	c.290C>T	p.Ala97Val	missense_variant	2/3	1	NM_058195.4	ENSP00000462950.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1451924 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 722664

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:3

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Melanoma-pancreatic cancer syndrome Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Myriad Genetics, Inc.

Mar 08, 2023

This variant is considered likely pathogenic. This variant is expected to disrupt protein structure [Myriad internal data]. Functional studies indicate this variant impacts protein function [PMID: 35001868, 9324288]. This variant has been reported in multiple individuals with clinical features of gene-specific disease [PMID: 21462282, 16234564]. -

Melanoma and neural system tumor syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Baylor Genetics

May 26, 2023

- -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 11, 2023

The p.H83Y variant (also known as c.247C>T), located in coding exon 2 of the CDKN2A gene, results from a C to T substitution at nucleotide position 247. The histidine at codon 83 is replaced by tyrosine, an amino acid with similar properties. This alteration was identified in cohorts with sporadic and multiple melanomas (Begg CB et al. J Natl Cancer Inst, 2005 Oct;97:1507-15; Miller PJ et al. Hum Mutat, 2011 Aug;32:900-11). Protein functional studies have shown this variant to have inhibited CDK4 and CDK6 binding and to have increased proliferation activity compared to wild-type (Yang R et al. Cancer Res, 1995 Jun;55:2503-6; Gombart AF et al. Leukemia, 1997 Oct;11:1673-80; Yarbrough WG et al. J Natl Cancer Inst, 1999 Sep;91:1569-74). This amino acid position is highly conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Familial melanoma Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 24, 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. This sequence change replaces histidine, which is basic and polar, with tyrosine, which is neutral and polar, at codon 83 of the CDKN2A (p16INK4a) protein (p.His83Tyr). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with sporadic and multiple primary melanomas (PMID: 16234564, 16896043, 21462282). This variant is also known as c.290C>T (p.Ala97Val) in the CDKN2A (p14ARF) transcript. ClinVar contains an entry for this variant (Variation ID: 376307). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. Experimental studies have shown that this missense change affects CDKN2A (p16INK4a) function (PMID: 7780957, 8521414, 9324288, 10491434). 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
AlphaMissense	Pathogenic	0.79
BayesDel_addAF	Pathogenic	0.19	D
BayesDel_noAF	Uncertain	0.030
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Benign	0.077	T;T
Eigen	Pathogenic	0.75
Eigen_PC	Pathogenic	0.80
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Benign	0.55	.;T
M_CAP	Pathogenic	0.31	D
MetaRNN	Uncertain	0.47	T;T
MetaSVM	Uncertain	-0.20	T
PROVEAN	Uncertain	-3.1	.;D
REVEL	Uncertain	0.58
Sift	Benign	0.037	.;D
Sift4G	Benign	0.082	T;T
Vest4		0.44
MVP		1.0
ClinPred		0.92	D
GERP RS		5.9

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: rs121913385; hg19: chr9-21971111; COSMIC: COSV58682852; COSMIC: COSV58682852;