9-21974685-G-T

Variant names:

• chr9-21974685-G-T
• rs763804037
• NM_000077.5:c.143C>A

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM1 PM2 PM5 PP3_Strong

The NM_000077.5(CDKN2A):​c.143C>A​(p.Pro48Gln) variant causes a missense change. 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 Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P48L) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: CDKN2A NM_000077.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 6.09

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]

ENSG00000264545 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 10 ACMG points.

• PM1: In a turn (size 2) in uniprot entity CDN2A_HUMAN there are 4 pathogenic changes around while only 0 benign (100%) in NM_000077.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chrnull-null-null-null is described in UniProt as null.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.947

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CDKN2A	NM_000077.5	c.143C>A	p.Pro48Gln	missense_variant	Exon 1 of 3	ENST00000304494.10	NP_000068.1
CDKN2A	NM_058195.4	c.194-3477C>A		intron_variant	Intron 1 of 2	ENST00000579755.2	NP_478102.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CDKN2A	ENST00000304494.10	c.143C>A	p.Pro48Gln	missense_variant	Exon 1 of 3	1	NM_000077.5	ENSP00000307101.5
CDKN2A	ENST00000579755.2	c.194-3477C>A		intron_variant	Intron 1 of 2	1	NM_058195.4	ENSP00000462950.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Melanoma-pancreatic cancer syndrome Uncertain:1

Jan 27, 2025

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Familial melanoma Uncertain:1

Jul 05, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with melanoma and/or pancreatic ductal adenocarcinoma (PMID: 28830827, 32482799). ClinVar contains an entry for this variant (Variation ID: 1042953). 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 this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant disrupts the p.Pro48 amino acid residue in CDKN2A (p16INK4a). Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 9168184, 10338331, 10491434, 11556834, 21462282). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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. This sequence change replaces proline, which is neutral and non-polar, with glutamine, which is neutral and polar, at codon 48 of the CDKN2A (p16INK4a) protein (p.Pro48Gln). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.95
BayesDel_addAF	Pathogenic	0.31	D
BayesDel_noAF	Pathogenic	0.20
CADD	Uncertain	26
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.57	D;T;.
Eigen	Pathogenic	0.71
Eigen_PC	Uncertain	0.58
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Uncertain	0.87	D;D;D
M_CAP	Pathogenic	0.73	D
MetaRNN	Pathogenic	0.95	D;D;D
MetaSVM	Pathogenic	1.0	D
PrimateAI	Uncertain	0.61	T
PROVEAN	Uncertain	-4.3	D;.;D
REVEL	Pathogenic	0.75
Sift	Uncertain	0.020	D;.;D
Sift4G	Uncertain	0.0030	D;D;D
Polyphen		1.0	D;.;.
Vest4		0.64
MutPred		0.78		Gain of MoRF binding (P = 0.0532);Gain of MoRF binding (P = 0.0532);Gain of MoRF binding (P = 0.0532);
MVP		1.0
MPC		1.2
ClinPred		0.99	D
GERP RS		4.9
Varity_R		0.51
gMVP		0.95

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: rs763804037; hg19: chr9-21974684; COSMIC: COSV100446243; COSMIC: COSV100446243;