chr9-21971181-C-T

Variant names:

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1PM2PM5PP3_Moderate

The NM_000077.5(CDKN2A):c.178G>A(p.Ala60Thr) variant causes a missense change. The variant allele was found at a frequency of 0.00000125 in 1,597,272 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic 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. A60V) has been classified as Likely pathogenic.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 6.9e-7 ( 0 hom. )

Consequence

CDKN2A
NM_000077.5 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:4

Conservation

PhyloP100: 5.60

Variant links:

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]

CDKN2A links:

ENSG00000264545 (HGNC:):

ENSG00000264545 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

PM1

In a repeat ANK 2 (size 28) in uniprot entity CDN2A_HUMAN there are 15 pathogenic changes around while only 3 benign (83%) in NM_000077.5

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr9-21971180-G-A is described in Lovd as [Likely_pathogenic].

PP3

MetaRNN computational evidence supports a deleterious effect, 0.851

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CDKN2A	NM_000077.5 link	c.178G>A	p.Ala60Thr	missense_variant	Exon 2 of 3	ENST00000304494.10	NP_000068.1	P42771-1K7PML8
CDKN2A	NM_058195.4 link	c.221G>A	p.Gly74Asp	missense_variant	Exon 2 of 3	ENST00000579755.2	NP_478102.2	Q8N726-1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CDKN2A	ENST00000304494.10 link	c.178G>A	p.Ala60Thr	missense_variant	Exon 2 of 3	1	NM_000077.5	ENSP00000307101.5		P42771-1
CDKN2A	ENST00000579755.2 link	c.221G>A	p.Gly74Asp	missense_variant	Exon 2 of 3	1	NM_058195.4	ENSP00000462950.1		Q8N726-1

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152218

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

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

GnomAD3 exomes

AF:

0.00000457

AC:

AN:

218966

Hom.:

AF XY:

0.00000819

AC XY:

AN XY:

122042

show subpopulations

Gnomad AFR exome

AF:

0.0000765

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

6.92e-7

AC:

AN:

1445054

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

719208

show subpopulations

Gnomad4 AFR exome

AF:

0.0000300

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:

AN:

152218

Hom.:

Cov.:

AF XY:

0.0000134

AC XY:

AN XY:

74368

show subpopulations

Gnomad4 AFR

AF:

0.0000241

Gnomad4 AMR

AF:

0.00

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

ExAC

AF:

0.00000838

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Hereditary cancer-predisposing syndrome

Uncertain:2

Nov 26, 2019

Color Diagnostics, LLC DBA Color Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces alanine with threonine at codon 60 of the CDKN2A protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). Splice site prediction tools suggest that this variant may not impact RNA splicing. Experimental functional studies have shown that this variant results in reduced cell cycle arrest activity (PMID 21462282). This variant has been reported in a melanoma tumor (PMID 8023167) and in the germline of two individuals without melanoma (PMID 21462282). This variant has been identified in 1/218966 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance. -

Jan 12, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.A60T variant (also known as c.178G>A), located in coding exon 2 of the CDKN2A gene, results from a G to A substitution at nucleotide position 178. The alanine at codon 60 is replaced by threonine, an amino acid with similar properties. In one study, this alteration was reported in 2 individuals without a history of melanoma, and not detected in any familial melanoma cases. Authors also performed a cell cycle arrest assay, which showed that this alteration causes a significant reduction in cell cycle arrest compared to wild-type (Miller PJ et al. Hum. Mutat. 2011 Aug;32(8):900-11). This amino acid position is highly conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

not provided

Uncertain:1

May 20, 2022

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

Familial melanoma

Uncertain:1

May 15, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

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 replaces alanine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 60 of the CDKN2A (p16INK4a) protein (p.Ala60Thr). This variant is present in population databases (rs769382085, gnomAD 0.008%). This missense change has been observed in individual(s) with melanoma (PMID: 8023167). This variant is also known as c.221G>A (p.Gly74Asp) in the CDKN2A (p14ARF) transcript. ClinVar contains an entry for this variant (Variation ID: 406705). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. Experimental studies have shown that this missense change affects CDKN2A (p16INK4a) function (PMID: 21462282). 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

Uncertain

0.35

BayesDel_addAF

Uncertain

0.11

BayesDel_noAF

Uncertain

-0.010

CADD

Uncertain

DANN

Uncertain

1.0

DEOGEN2

Uncertain

0.46

T;T;.;.;.;.;T;.

Eigen

Uncertain

0.43

Eigen_PC

Uncertain

0.44

FATHMM_MKL

Uncertain

0.96

LIST_S2

Uncertain

0.97

D;D;.;D;.;D;D;D

M_CAP

Pathogenic

0.71

MetaRNN

Pathogenic

0.85

D;D;D;D;D;D;D;D

MetaSVM

Uncertain

0.019

PrimateAI

Uncertain

0.57

PROVEAN

Uncertain

-3.7

D;.;.;D;.;.;.;.

REVEL

Uncertain

0.57

Sift

Uncertain

0.0030

D;.;.;D;.;.;.;.

Sift4G

Uncertain

0.0030

D;D;D;D;D;D;D;D

Polyphen

0.99

D;.;.;.;.;.;.;.

Vest4

0.65

MutPred

0.45

Gain of phosphorylation at A60 (P = 0.0528);Gain of phosphorylation at A60 (P = 0.0528);.;Gain of phosphorylation at A60 (P = 0.0528);.;.;.;.;

MVP

0.94

MPC

1.2

ClinPred

0.62

GERP RS

5.8

Varity_R

0.54

gMVP

0.77

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.020

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over