chr9-21971150-G-A

Variant names:

• chr9-21971150-G-A
• rs786202575
• NM_000077.5:c.209C>T

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM1 PM2 PP3_Moderate

The NM_000077.5(CDKN2A):​c.209C>T​(p.Pro70Leu) variant causes a missense 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. 12/21 in silico tools predict a damaging 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. P70S) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: CDKN2A NM_000077.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 9.23

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

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PM1: In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 16 uncertain in NM_000077.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.896

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CDKN2A	NM_000077.5	c.209C>T	p.Pro70Leu	missense_variant	Exon 2 of 3	ENST00000304494.10	NP_000068.1
CDKN2A	NM_058195.4	c.252C>T	p.Ala84Ala	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.209C>T	p.Pro70Leu	missense_variant	Exon 2 of 3	1	NM_000077.5	ENSP00000307101.5
CDKN2A	ENST00000579755.2	c.252C>T	p.Ala84Ala	synonymous_variant	Exon 2 of 3	1	NM_058195.4	ENSP00000462950.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Familial melanoma Uncertain:1

Jan 19, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, this variant is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in the germline of individuals with a CDKN2A-related disease. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies. This sequence change replaces proline with leucine at codon 70 of the CDKN2A protein (p.Pro70Leu). The proline residue is highly conserved and there is a moderate physicochemical difference between proline and leucine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.60
BayesDel_addAF	Pathogenic	0.35	D
BayesDel_noAF	Pathogenic	0.27
CADD	Pathogenic	26
DANN	Pathogenic	1.0
DEOGEN2	Uncertain	0.53	D;T;.;.;.;.;T;.
Eigen	Pathogenic	0.71
Eigen_PC	Pathogenic	0.72
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D;D;.;D;.;D;D;D
M_CAP	Pathogenic	0.73	D
MetaRNN	Pathogenic	0.90	D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.86	D
PhyloP100		9.2
PrimateAI	Uncertain	0.57	T
PROVEAN	Pathogenic	-9.2	D;.;.;D;.;.;.;.
REVEL	Pathogenic	0.74
Sift	Uncertain	0.0020	D;.;.;D;.;.;.;.
Sift4G	Uncertain	0.037	D;T;D;D;D;D;D;D
Polyphen		1.0	D;.;.;.;.;.;.;.
Vest4		0.68
MutPred		0.53		Loss of disorder (P = 0.0427);Loss of disorder (P = 0.0427);.;Loss of disorder (P = 0.0427);.;.;.;.;
MVP		1.0
MPC		1.2
ClinPred		1.0	D
GERP RS		5.8
PromoterAI		-0.0093	Neutral
Varity_R		0.67
gMVP		0.84
Mutation Taster		=1/99	disease causing

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

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Other links and lift over

dbSNP: rs786202575; hg19: chr9-21971149; COSMIC: COSV58701883;