9-21974696-G-T

Variant names:

• chr9-21974696-G-T
• rs1554656253
• NM_000077.5:c.132C>A

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_000077.5(CDKN2A):​c.132C>A​(p.Tyr44*) 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 (★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 32)
• Consequence: CDKN2A NM_000077.5 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: -1.03

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 12 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 9-21974696-G-T is Pathogenic according to our data. Variant chr9-21974696-G-T is described in ClinVar as [Pathogenic]. Clinvar id is 655275.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chr9-21974696-G-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CDKN2A	NM_000077.5	c.132C>A	p.Tyr44*	stop_gained	Exon 1 of 3	ENST00000304494.10	NP_000068.1
CDKN2A	NM_058195.4	c.194-3488C>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.132C>A	p.Tyr44*	stop_gained	Exon 1 of 3	1	NM_000077.5	ENSP00000307101.5
CDKN2A	ENST00000579755.2	c.194-3488C>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: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Pathogenic:1

Mar 10, 2025

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.Y44* pathogenic mutation (also known as c.132C>A), located in coding exon 1 of the CDKN2A gene, results from a C to A substitution at nucleotide position 132. This changes the amino acid from a tyrosine to a stop codon within coding exon 1. This variant has been observed in individuals with melanoma (MacKie RM et al. J. Invest. Dermatol. 1998 Aug;111(2):269-72; Begg CB et al. J. Natl. Cancer Inst. 2005 Oct;97(20):1507-15). Other alterations (c.132dupA, c.131_132insAA, c.132delC, c.132C>G) also resulting in the same stop codon (p.Y44*) have been reported in individuals with melanoma and pancreatic cancer (Ambry internal data; de Snoo FA et al. J. Am. Acad. Dermatol. 2007 May;56(5):748-52). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). This alteration is expected to result in loss of function by premature protein truncation or nonsense-mediated mRNA decay. As such, this alteration is interpreted as a disease-causing mutation. -

Familial melanoma Pathogenic:1

Nov 06, 2018

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Tyr44*) in the CDKN2A (p16INK4a) gene. It is expected to result in an absent or disrupted protein product. This variant is not present in population databases (ExAC no frequency). This variant has been observed in an individual and a family affected with melanoma (PMID: 9699728, 16234564). Loss-of-function variants in CDKN2A (p16INK4a) are known to be pathogenic (PMID: 15146471, 16905682). For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.37	D
BayesDel_noAF	Pathogenic	0.29
CADD	Pathogenic	34
DANN	Uncertain	0.98
Eigen	Benign	-0.37
Eigen_PC	Benign	-0.75
FATHMM_MKL	Benign	0.20	N
Vest4		0.60
GERP RS		-2.6

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.27		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.27		Position offset: -1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1554656253; hg19: chr9-21974695; COSMIC: COSV58689440; COSMIC: COSV58689440;