9-21971210-T-C

Variant names:

• chr9-21971210-T-C
• rs1554654224
• NM_000077.5:c.151-2A>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.151-2A>G variant causes a splice acceptor, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: CDKN2A NM_000077.5 splice_acceptor, intron
• Scores: Splicing: ADA: 0.9999
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3 O:1
• Conservation: PhyloP100: 7.37

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 18 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 9-21971210-T-C is Pathogenic according to our data. Variant chr9-21971210-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 487034.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.151-2A>G		splice_acceptor_variant, intron_variant	Intron 1 of 2	ENST00000304494.10	NP_000068.1
CDKN2A	NM_058195.4	c.194-2A>G		splice_acceptor_variant, 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.151-2A>G		splice_acceptor_variant, intron_variant	Intron 1 of 2	1	NM_000077.5	ENSP00000307101.5
CDKN2A	ENST00000579755.2	c.194-2A>G		splice_acceptor_variant, intron_variant	Intron 1 of 2	1	NM_058195.4	ENSP00000462950.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Pathogenic:1

Sep 03, 2024

Ambry Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.151-2A>G intronic variant results from an A to G substitution two nucleotides upstream from coding exon 2 in the CDKN2A gene. This alteration has been reported in individuals with a personal or family history of melanoma and/or pancreatic cancer (Ambry internal data; Maubec E et al. J. Am. Acad. Dermatol., 2012 Dec;67:1257-64; Taylor NJ et al. J. Invest. Dermatol., 2017 12;137:2606-2612; Overbeek, KA et al. J Med Genet 2021 Apr;58(4):264-269). It has also been reported in two relatives affected with soft tissue sarcoma (Jouenne F et al. J. Med. Genet., 2017 09;54:607-612). This nucleotide position is highly conserved in available vertebrate species. In silico splice site analysis predicts that this alteration will weaken the native splice acceptor site and will result in the creation or strengthening of a novel splice acceptor site. Alterations that disrupt the canonical splice site are expected to cause aberrant splicing, resulting in an abnormal protein or a transcript that is subject to nonsense-mediated mRNA decay. As such, this alteration is classified as likely pathogenic. -

Familial pancreatic carcinoma Pathogenic:1

Apr 04, 2024

Institute of Human Genetics, University of Leipzig Medical Center

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Criteria applied: PVS1_STR,PS4_MOD,PM2_SUP -

Familial melanoma Pathogenic:1

Aug 31, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The CDKN2A gene encodes two different proteins, p16INK4a and p14ARF, which are translated from alternative transcripts with different open reading frames. Both transcripts have been analyzed. We report either the variant with the higher classification or default to the CDKN2A (p16INK4a) variant. This report therefore includes the details for the CDKN2A (p16INK4a) variant. This sequence change affects an acceptor splice site in intron 1 of the CDKN2A (p16INK4a) gene. RNA analysis indicates that disruption of this splice site induces altered splicing and may result in an absent or altered protein product. This variant is not present in population databases (gnomAD no frequency). Disruption of this splice site has been observed in individual(s) with clinical features of melanoma-NST syndrome (PMID: 11433531, 11687599, 22841127, 28592523, 28830827). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 487034). Studies have shown that disruption of this splice site results in skipping of exon 2, and produces a non-functional protein and/or introduces a premature termination codon (PMID: 11433531, 12920094). For these reasons, this variant has been classified as Pathogenic. The evidence indicates that this variant confers risk of developing CDKN2A (p16INK4a) and CDKN2A (p14ARF)-associated conditions. -

not provided Other:1

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MutSpliceDB: a database of splice sites variants effects on splicing, NIH

Significance: not provided

Review Status: no classification provided

Collection Method: research

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.14
CADD	Pathogenic	35
DANN	Uncertain	0.99
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.89
FATHMM_MKL	Pathogenic	0.98	D
GERP RS		5.7

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.67		Position offset: -19
DS_AL_spliceai		1.0		Position offset: -2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1554654224; hg19: chr9-21971209; COSMIC: COSV58692823; COSMIC: COSV58692823;