chr9-21971051-C-G

Variant names:

• chr9-21971051-C-G
• rs143282362
• NM_000077.5:c.308G>C

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP3

The NM_000077.5(CDKN2A):​c.308G>C​(p.Arg103Pro) 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 pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: CDKN2A NM_000077.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:4
• Conservation: PhyloP100: 0.443

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 Uncertain_significance. Variant got 5 ACMG points.

• PM1: In a chain Cyclin-dependent kinase inhibitor 2A (size 155) in uniprot entity CDN2A_HUMAN there are 42 pathogenic changes around while only 12 benign (78%) in NM_000077.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.759

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CDKN2A	NM_000077.5	c.308G>C	p.Arg103Pro	missense_variant	Exon 2 of 3	ENST00000304494.10	NP_000068.1
CDKN2A	NM_058195.4	c.351G>C	p.Ala117Ala	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.308G>C	p.Arg103Pro	missense_variant	Exon 2 of 3	1	NM_000077.5	ENSP00000307101.5
CDKN2A	ENST00000579755.2	c.351G>C	p.Ala117Ala	synonymous_variant	Exon 2 of 3	1	NM_058195.4	ENSP00000462950.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 6.88e-7 AC: 1 AN: 1453112 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 723176

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: 9.00e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:2

Dec 04, 2024

Quest Diagnostics Nichols Institute San Juan Capistrano

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The CDKN2A c.308G>C (p.Arg103Pro) variant has not been reported in individuals with CDKN2A-related conditions in the published literature. It also has not been reported in large, multi-ethnic general populations (Genome Aggregation Database, http://gnomad.broadinstitute.org). Analysis of this variant using bioinformatics tools for the prediction of the effect of amino acid changes on protein structure and function yielded predictions that this variant is damaging. Based on the available information, we are unable to determine the clinical significance of this variant. -

Feb 09, 2021

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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 -

Hereditary cancer-predisposing syndrome Uncertain:1

Apr 18, 2022

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.R103P variant (also known as c.308G>C), located in coding exon 2 of the CDKN2A gene, results from a G to C substitution at nucleotide position 308. The arginine at codon 103 is replaced by proline, an amino acid with dissimilar properties. This amino acid position is well 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. -

Familial melanoma Uncertain:1

Dec 12, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine, which is basic and polar, with proline, which is neutral and non-polar, at codon 103 of the CDKN2A (p16INK4a) protein (p.Arg103Pro). 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. ClinVar contains an entry for this variant (Variation ID: 406703). 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 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	0.31
BayesDel_addAF	Pathogenic	0.21	D
BayesDel_noAF	Uncertain	0.070
CADD	Benign	19
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.42	T;T;.;.;.;.;T;.
Eigen	Benign	0.056
Eigen_PC	Benign	-0.0030
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Uncertain	0.91	D;D;.;D;.;D;D;D
M_CAP	Pathogenic	0.62	D
MetaRNN	Pathogenic	0.76	D;D;D;D;D;D;D;D
MetaSVM	Benign	-0.48	T
PrimateAI	Benign	0.44	T
PROVEAN	Uncertain	-3.5	D;.;.;D;.;.;.;.
REVEL	Uncertain	0.40
Sift	Benign	0.047	D;.;.;T;.;.;.;.
Sift4G	Benign	0.096	T;T;T;T;T;T;T;T
Polyphen		1.0	D;.;.;.;.;.;.;.
Vest4		0.58
MutPred		0.56		Loss of MoRF binding (P = 6e-04);Loss of MoRF binding (P = 6e-04);.;Loss of MoRF binding (P = 6e-04);.;.;.;.;
MVP		1.0
MPC		0.85
ClinPred		0.69	D
GERP RS		2.1
Varity_R		0.42
gMVP		0.87

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: rs143282362; hg19: chr9-21971050;