NM_000077.5:c.242C>T

Variant names:

• chr9-21971117-G-A
• rs11552823
• NM_000077.5:c.242C>T

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000077.5(CDKN2A):​c.242C>T​(p.Pro81Leu) variant causes a missense change. The variant allele was found at a frequency of 0.000000689 in 1,451,860 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P81S) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: CDKN2A NM_000077.5 missense
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 5.60
• Publications: 52 publications found

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 Gene-Disease associations (from GenCC):

• melanoma, cutaneous malignant, susceptibility to, 2

  Inheritance: AD Classification: DEFINITIVE Submitted by: G2P
• melanoma-pancreatic cancer syndrome

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Genomics England PanelApp, ClinGen, Labcorp Genetics (formerly Invitae), Ambry Genetics
• familial atypical multiple mole melanoma syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• melanoma and neural system tumor syndrome

  Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics

ENSG00000264545 (HGNC:):

ACMG classification

Our verdict: Pathogenic. The variant received 18 ACMG points.

• PM1: In a hotspot region, there are 12 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 49 uncertain 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 chr9-21971118-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 664812.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.976
• PP5: Variant 9-21971117-G-A is Pathogenic according to our data. Variant chr9-21971117-G-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 833629.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CDKN2A	NM_000077.5	c.242C>T	p.Pro81Leu	missense_variant	Exon 2 of 3	ENST00000304494.10	NP_000068.1
CDKN2A	NM_058195.4	c.285C>T	p.Thr95Thr	synonymous_variant	Exon 2 of 3	ENST00000579755.2	NP_478102.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CDKN2A	ENST00000304494.10	c.242C>T	p.Pro81Leu	missense_variant	Exon 2 of 3	1	NM_000077.5	ENSP00000307101.5
CDKN2A	ENST00000579755.2	c.285C>T	p.Thr95Thr	synonymous_variant	Exon 2 of 3	1	NM_058195.4	ENSP00000462950.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000434 AC: 1 AN: 230332 AF XY: 0.00000786

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000293

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.89e-7 AC: 1 AN: 1451860 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 722658

African (AFR) AF: 0.00 AC: 0 AN: 33440

American (AMR) AF: 0.0000224 AC: 1 AN: 44654

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26076

East Asian (EAS) AF: 0.00 AC: 0 AN: 39664

South Asian (SAS) AF: 0.00 AC: 0 AN: 86164

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 44626

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5472

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111516

Other (OTH) AF: 0.00 AC: 0 AN: 60248

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Pathogenic:1

Sep 05, 2025

Ambry Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.P81L variant (also known as c.242C>T), located in coding exon 2 of the CDKN2A gene, results from a C to T substitution at nucleotide position 242. The proline at codon 81 is replaced by leucine, an amino acid with similar properties. Of note, this alteration is also known as c.285C>T (p.T95T) in the p14(ARF) isoform. In several assays testing CDKN2A function, this variant showed functionally abnormal results (Reymond A et al. Oncogene. 1995 Sep;11(6):1173-8; Walker GJ et al. Int J Cancer. 1999 Jul;82(2):305-12). Based on internal structural analysis, this variant is anticipated to disrupt a region of known function and is anticipated to result in a significant decrease in structural stability (Zhang B et al. J Biol Chem. 1996 Nov;271(46):28734-7; Byeon IJ et al. Mol Cell. 1998 Feb;1(3):421-31; Russo AA et al. Nature. 1998 Sep;395(6699):237-43; Ambry internal data). Another variant at the same codon, p.P81S (c.241C>T), has been identified in individuals with features consistent with melanoma-pancreatic cancer syndrome (Ambry internal data). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the majority of available evidence to date, this variant is likely to be pathogenic.

Familial melanoma Pathogenic:1

Jun 05, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces proline, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 81 of the CDKN2A (p16INK4a) protein (p.Pro81Leu). In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. This variant disrupts the p.Pro81 amino acid residue in CDKN2A (p16INK4a). Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 18023021, 19260062, 21462282, 26800492, 27804060). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. Experimental studies have shown that this missense change affects CDKN2A (p16INK4a) function (PMID: 7566978, 10389768, 12614625, 18951449). 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. ClinVar contains an entry for this variant (Variation ID: 833629). This missense change has been observed in individual(s) with melanoma (PMID: 11687599). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database.

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.84
BayesDel_addAF	Pathogenic	0.44	D
BayesDel_noAF	Pathogenic	0.47
CADD	Pathogenic	27
DANN	Pathogenic	1.0
DEOGEN2	Uncertain	0.55	D;T;.;.;.;.;T;.
Eigen	Pathogenic	0.81
Eigen_PC	Pathogenic	0.82
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.99	D;D;.;D;.;D;D;D
M_CAP	Pathogenic	0.63	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.18	D
MutationAssessor	Benign	0.0	.;.;.;.;.;.;.;.
PhyloP100		5.6
PrimateAI	Uncertain	0.73	T
PROVEAN	Pathogenic	-8.8	D;.;.;D;.;.;.;.
REVEL	Pathogenic	0.86
Sift	Uncertain	0.0090	D;.;.;D;.;.;.;.
Sift4G	Uncertain	0.0080	D;D;D;D;D;D;D;D
Vest4		0.89
ClinPred		0.94	D
GERP RS		5.9
PromoterAI		0.0027	Neutral
Varity_R		0.67
gMVP		0.95
Mutation Taster		=1/99	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.15		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs11552823; hg19: chr9-21971116; COSMIC: COSV58683884; COSMIC: COSV58683884;