9-21994141-G-T

Position:

• chr9-21994141-G-T

Variant summary

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

The NM_058195.4(CDKN2A):​c.191C>A​(p.Pro64Gln) variant causes a missense, splice region 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. 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. P64R) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: CDKN2A NM_058195.4 missense, splice_region
• Scores: Splicing: ADA: 0.7456
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 2.58

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]

CDKN2B-AS1 (HGNC:34341): (CDKN2B antisense RNA 1) This gene is located within the CDKN2B-CDKN2A gene cluster at chromosome 9p21. The gene product is a functional RNA molecule that interacts with polycomb repressive complex-1 (PRC1) and -2 (PRC2), leading to epigenetic silencing of other genes in this cluster. This region is a significant genetic susceptibility locus for cardiovascular disease, and has also been linked to a number of other pathologies, including several cancers, intracranial aneurysm, type-2 diabetes, periodontitis, Alzheimer's disease, endometriosis, frailty in the elderly, and glaucoma. Multiple alternatively processed transcript variants have been detected, some of which may take the form of circular RNA molecules (PMID:21151960). [provided by RefSeq, May 2014]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM1: In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 3 benign, 17 uncertain in NM_058195.4
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CDKN2A	NM_058195.4	c.191C>A	p.Pro64Gln	missense_variant, splice_region_variant	1/3	ENST00000579755.2
CDKN2A	NM_001363763.2	c.-4+680C>A		intron_variant
CDKN2A	XM_047422597.1	c.-4+406C>A		intron_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CDKN2A	ENST00000579755.2	c.191C>A	p.Pro64Gln	missense_variant, splice_region_variant	1/3	1	NM_058195.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 14, 2023

The p.P64Q variant (also known as c.191C>A), located in coding exon 1b of the CDKN2A (p14ARF) gene, results from a C to A substitution at nucleotide position 191. The proline at codon 64 is replaced by glutamine, an amino acid with similar 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

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 12, 2021

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Uncertain	0.065	T
BayesDel_noAF	Benign	-0.14
CADD	Pathogenic	29
DANN	Uncertain	0.99
DEOGEN2	Benign	0.080	T;T
Eigen	Uncertain	0.31
Eigen_PC	Uncertain	0.35
FATHMM_MKL	Benign	0.68	D
LIST_S2	Benign	0.48	.;T
M_CAP	Pathogenic	0.30	D
MetaRNN	Benign	0.31	T;T
MetaSVM	Uncertain	-0.23	T
MutationTaster	Benign	0.75	D;D;D;D;N
PrimateAI	Uncertain	0.55	T
PROVEAN	Uncertain	-4.0	.;D
REVEL	Uncertain	0.37
Sift	Uncertain	0.0060	.;D
Sift4G	Uncertain	0.014	D;D
Vest4		0.36
MVP		1.0
ClinPred		0.96	D
GERP RS		4.2

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Benign	0.75
dbscSNV1_RF	Pathogenic	0.77
SpliceAI score (max)		0.44		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.44		Position offset: 10

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1348413029; hg19: chr9-21994140;