chr9-21974777-GGCCA-G

Position:

• chr9-21974777-GGCCA-G

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000077.5(CDKN2A):​c.47_50del​(p.Leu16ProfsTer9) variant causes a frameshift change. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: CDKN2A NM_000077.5 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3 O:1
• Conservation: PhyloP100: 5.50

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 Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 49 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 9-21974777-GGCCA-G is Pathogenic according to our data. Variant chr9-21974777-GGCCA-G is described in ClinVar as [Pathogenic]. Clinvar id is 142061.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CDKN2A	NM_000077.5	c.47_50del	p.Leu16ProfsTer9	frameshift_variant	1/3	ENST00000304494.10	NP_000068.1
CDKN2A	NM_058195.4	c.194-3573_194-3570del		intron_variant		ENST00000579755.2	NP_478102.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CDKN2A	ENST00000304494.10	c.47_50del	p.Leu16ProfsTer9	frameshift_variant	1/3	1	NM_000077.5	ENSP00000307101	P2
CDKN2A	ENST00000579755.2	c.194-3573_194-3570del		intron_variant		1	NM_058195.4	ENSP00000462950

Frequencies

GnomAD3 genomes Cov.: 32

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Squamous cell lung carcinoma Pathogenic:1

Likely pathogenic, no assertion criteria provided

clinical testing;in vivo

Faculté Pluridciplinaire Nador, Université Mohamed Premier

May 05, 2020

- -

Hereditary cancer-predisposing syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Apr 21, 2022

The c.47_50delTGGC pathogenic mutation, located in coding exon 1 of the CDKN2A gene, results from a deletion of 4 nucleotides at nucleotide positions 47 to 50, causing a translational frameshift with a predicted alternate stop codon (p.L16Pfs*9). This pathogenic mutation has been reported in an individual diagnosed with multiple primary melanomas beginning at age 40 and whose father had pancreatic cancer (Wadt KA et al. PLoS ONE. 2015 Mar;10:e0122662). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). In addition to the clinical data presented in the literature, 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

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 10, 2024

This sequence change creates a premature translational stop signal (p.Leu16Profs*9) in the CDKN2A (p16INK4a) gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in CDKN2A (p16INK4a) are known to be pathogenic (PMID: 15146471, 16905682). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with multiple primary melanomas (PMID: 25803691). ClinVar contains an entry for this variant (Variation ID: 142061). For these reasons, this variant has been classified as Pathogenic. -

Neoplasm Other:1

-, criteria provided, single submitter

clinical testing

Center for Genomic Medicine, Rigshospitalet, Copenhagen University Hospital

Jul 31, 2024

- -

Computational scores

Source: dbNSFP v4.3

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: rs587782206; hg19: chr9-21974776;