rs774633329

chr9-21971133-C-Achr9-21971133-C-Gchr9-21971133-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 4P and 4B. PM1 PM2 BP4_Strong

The NM_000077.5(CDKN2A):c.226G>T(p.Ala76Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,148 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/20 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. A76T) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: CDKN2A NM_000077.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -0.113

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 0 ACMG points.

• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 17 uncertain in NM_000077.5
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.036679447).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CDKN2A	NM_000077.5	c.226G>T	p.Ala76Ser	missense_variant	2/3	ENST00000304494.10
CDKN2A	NM_058195.4	c.269G>T	p.Arg90Leu	missense_variant	2/3	ENST00000579755.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CDKN2A	ENST00000304494.10	c.226G>T	p.Ala76Ser	missense_variant	2/3	1	NM_000077.5	P2
CDKN2A	ENST00000579755.2	c.269G>T	p.Arg90Leu	missense_variant	2/3	1	NM_058195.4

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152148 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000654

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1443058 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 717846

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152148 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74320

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.0000654

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000756

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Familial melanoma Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Feb 13, 2022

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 replaces alanine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 76 of the CDKN2A (p16INK4a) protein (p.Ala76Ser). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with CDKN2A (p16INK4a)-related conditions. This variant is also known as c.269G>T (p.Arg90Leu) in the CDKN2A (p14ARF) transcript 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 tolerated. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.12
BayesDel_addAF	Uncertain	0.015	T
BayesDel_noAF	Benign	-0.20
Cadd	Benign	13
Dann	Uncertain	0.98
DEOGEN2	Benign	0.056	T;T;.;.;.;.;T;.
Eigen	Benign	-0.76
Eigen_PC	Benign	-0.70
FATHMM_MKL	Benign	0.23	N
LIST_S2	Benign	0.71	T;T;.;T;.;T;T;T
M_CAP	Benign	0.048	D
MetaRNN	Benign	0.037	T;T;T;T;T;T;T;T
MetaSVM	Benign	-0.91	T
MutationTaster	Benign	1.0	N;N;N;N;N;N;N;N;N;N;N;N
PrimateAI	Benign	0.28	T
PROVEAN	Benign	0.10	N;.;.;N;.;.;.;.
REVEL	Benign	0.19
Sift	Benign	0.56	T;.;.;T;.;.;.;.
Sift4G	Benign	0.77	T;T;T;T;T;T;T;T
Polyphen		0.084	B;.;.;.;.;.;.;.
Vest4		0.13
MutPred		0.23		Gain of glycosylation at A76 (P = 0.0163);Gain of glycosylation at A76 (P = 0.0163);.;Gain of glycosylation at A76 (P = 0.0163);.;.;.;.;
MVP		0.84
MPC		0.37
ClinPred		0.058	T
GERP RS		1.4
Varity_R		0.14
gMVP		0.60

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: rs774633329; hg19: chr9-21971132; COSMIC: COSV104609546; COSMIC: COSV104609546;