rs778971134

Positions:

• chr9-21971028-C-G
• chr9-21971028-C-T

Variant summary

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

The ENST00000304494.10(CDKN2A):​c.331G>C​(p.Gly111Arg) 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. G111D) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: CDKN2A ENST00000304494.10 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.87

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 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 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.331G>C	p.Gly111Arg	missense_variant	2/3	ENST00000304494.10	NP_000068.1
CDKN2A	NM_058195.4	c.374G>C	p.Gly125Ala	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.331G>C	p.Gly111Arg	missense_variant	2/3	1	NM_000077.5	ENSP00000307101	P2
CDKN2A	ENST00000579755.2	c.374G>C	p.Gly125Ala	missense_variant	2/3	1	NM_058195.4	ENSP00000462950

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 30, 2021

The p.G111R variant (also known as c.331G>C), located in coding exon 2 of the CDKN2A gene, results from a G to C substitution at nucleotide position 331. The glycine at codon 111 is replaced by arginine, an amino acid with dissimilar properties. This amino acid position is 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.66
BayesDel_addAF	Pathogenic	0.20	D
BayesDel_noAF	Uncertain	0.050
CADD	Uncertain	25
DANN	Uncertain	0.99
DEOGEN2	Benign	0.094	T;T
Eigen	Uncertain	0.58
Eigen_PC	Uncertain	0.61
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Benign	0.58	.;T
M_CAP	Pathogenic	0.58	D
MetaRNN	Uncertain	0.50	T;T
MetaSVM	Pathogenic	1.0	D
MutationTaster	Benign	0.79	D;D;D;D;D;D;D;D;D;D;D;D
PROVEAN	Pathogenic	-4.6	.;D
REVEL	Uncertain	0.55
Sift	Pathogenic	0.0	.;D
Sift4G	Pathogenic	0.0	D;D
Vest4		0.37
MVP		0.96
ClinPred		0.99	D
GERP RS		5.9

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: rs778971134; hg19: chr9-21971027;