9-21971097-C-T

Position:

• chr9-21971097-C-T

Variant summary

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

The ENST00000304494.10(CDKN2A):​c.262G>A​(p.Glu88Lys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. E88Q) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: CDKN2A ENST00000304494.10 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 3.38

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 Uncertain_significance. Variant got 4 ACMG points.

• PM1: In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 17 uncertain in ENST00000304494.10
• 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.262G>A	p.Glu88Lys	missense_variant	2/3	ENST00000304494.10	NP_000068.1
CDKN2A	NM_058195.4	c.305G>A	p.Gly102Glu	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.262G>A	p.Glu88Lys	missense_variant	2/3	1	NM_000077.5	ENSP00000307101	P2
CDKN2A	ENST00000579755.2	c.305G>A	p.Gly102Glu	missense_variant	2/3	1	NM_058195.4	ENSP00000462950

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1452574 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 723010

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: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 25, 2018

The p.E88K variant (also known as c.262G>A), located in coding exon 2 of the CDKN2A gene, results from a G to A substitution at nucleotide position 262. The glutamic acid at codon 88 is replaced by lysine, an amino acid with similar properties. This amino acid position is not well 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

Dec 11, 2021

The CDKN2A gene encodes two different proteins, p16INK4a and p14ARF, which are translated from alternative transcripts that have different open reading frames. Experimental studies have shown that this variant affects CDKN2A (p16INK4a) protein function (PMID: 21462282). The functional impact of p.Gly102Glu on p14ARF has not been tested. 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. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of p.Glu88Lys in p16INK4a (SIFT: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0") or on the effect of p.Gly102Glu in p14ARF (SIFT: "Tolerated"; PolyPhen-2: "Not Available"; Align-GVGD: "Class C65"). ClinVar contains an entry for this variant (Variation ID: 821566). This variant has not been reported in the literature in individuals affected with CDKN2A -related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glutamic acid with lysine at codon 88 of the CDKN2A (p16INK4a) protein (p.Glu88Lys). The glutamic acid residue is highly conserved and there is a small physicochemical difference between glutamic acid and lysine. Alternatively, this sequence change replaces glycine with glutamic acid at codon 102 of the CDKN2A (p14ARF) protein (p.Gly102Glu). The glycine residue is highly conserved and there is a moderate physicochemical difference between glycine and glutamic acid. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.77
BayesDel_addAF	Pathogenic	0.23	D
BayesDel_noAF	Uncertain	0.040
CADD	Pathogenic	26
DANN	Uncertain	0.99
DEOGEN2	Benign	0.19	T;T;.;.;.;.;T;.
Eigen	Uncertain	0.33
Eigen_PC	Uncertain	0.46
FATHMM_MKL	Uncertain	0.85	D
LIST_S2	Uncertain	0.91	D;T;.;D;.;T;T;T
M_CAP	Uncertain	0.21	D
MetaRNN	Uncertain	0.55	D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.13	D
MutationTaster	Benign	0.96	D;D;D;D;D;D;D;N;N;N;N;N
PrimateAI	Uncertain	0.63	T
PROVEAN	Benign	-2.1	N;.;.;N;.;.;.;.
REVEL	Uncertain	0.55
Sift	Benign	0.18	T;.;.;D;.;.;.;.
Sift4G	Benign	0.71	T;T;T;T;T;T;T;T
Polyphen		0.99	D;.;.;.;.;.;.;.
Vest4		0.46
MutPred		0.48		Gain of methylation at E88 (P = 0.0085);Gain of methylation at E88 (P = 0.0085);.;Gain of methylation at E88 (P = 0.0085);.;.;.;.;
MVP		1.0
MPC		1.2
ClinPred		0.93	D
GERP RS		5.9
Varity_R		0.37
gMVP		0.79

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: rs121913384; hg19: chr9-21971096; COSMIC: COSV58683670; COSMIC: COSV58683670;