9-21971053-C-A

Position:

• chr9-21971053-C-A

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 4P and 2B. PM1 PM2 BP4_Moderate

The NM_058195.4(CDKN2A):​c.349G>T​(p.Ala117Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 13/16 in silico tools predict a benign 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. A117V) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: CDKN2A NM_058195.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: -2.60

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 Uncertain_significance. Variant got 2 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 14 benign, 13 uncertain in NM_058195.4
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.1451897).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CDKN2A	NM_058195.4	c.349G>T	p.Ala117Ser	missense_variant	2/3	ENST00000579755.2
CDKN2A	NM_000077.5	c.306G>T	p.Ala102=	synonymous_variant	2/3	ENST00000304494.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CDKN2A	ENST00000579755.2	c.349G>T	p.Ala117Ser	missense_variant	2/3	1	NM_058195.4
CDKN2A	ENST00000304494.10	c.306G>T	p.Ala102=	synonymous_variant	2/3	1	NM_000077.5	P2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Apr 22, 2016

This variant is denoted CDKN2A c.349G>T at the cDNA level, p.Ala117Ser (A117S) at the protein level, and results in the change of an Alanine to a Serine (GCG>TCG) in exon 2 of the p14-ARF protein. Of note, the CDKN2A gene encodes the p16 protein, and using an alternate reading frame, the p14-ARF protein as well. This variant also results in a change to the p16 transcript; however, that nucleotide substitution is silent (p.Ala102Ala) at the protein level. This variant has not, to our knowledge, been published in the literature as pathogenic or benign. CDKN2A Ala117Ser was not observed in approximately 6,500 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, suggesting it is not a common benign variant in these populations. Since Alanine and Serine differ in polarity, charge, size or other properties, this is considered a non-conservative amino acid substitution. CDKN2A Ala117Ser occurs at a position that is not conserved and is not located in a known functional domain (UniProt). In silico analyses predict that this variant is unlikely to alter protein structure or function. Based on currently available evidence, it is unclear whether CDKN2A Ala117Ser is a pathogenic or benign variant. We consider it to be a variant of uncertain significance. -

Familial melanoma Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 16, 2021

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Benign	0.0052	T
BayesDel_noAF	Benign	-0.23
CADD	Benign	6.4
DANN	Benign	0.95
DEOGEN2	Benign	0.025	T;T
Eigen	Benign	-0.65
Eigen_PC	Benign	-0.65
FATHMM_MKL	Benign	0.26	N
LIST_S2	Benign	0.42	.;T
M_CAP	Uncertain	0.25	D
MetaRNN	Benign	0.15	T;T
MetaSVM	Benign	-0.92	T
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D;D;N;N;N
PrimateAI	Benign	0.41	T
PROVEAN	Benign	-1.2	.;N
REVEL	Benign	0.18
Sift	Benign	0.17	.;T
Sift4G	Benign	0.26	T;T
Vest4		0.17
MVP		0.81
ClinPred		0.17	T
GERP RS		0.56

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: rs1064794863; hg19: chr9-21971052;