9-21971100-G-T

Position:

• chr9-21971100-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 6P and 2B. PM1 PM2 PM5 BP4_Moderate

The NM_058195.4(CDKN2A):​c.302C>A​(p.Pro101Gln) 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. 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. P101L) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: CDKN2A NM_058195.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.952

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 4 ACMG points.

• PM1: In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 12 benign, 16 uncertain in NM_058195.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr9-21971100-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 406707.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BP4: Computational evidence support a benign effect (MetaRNN=0.15947267).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CDKN2A	NM_058195.4	c.302C>A	p.Pro101Gln	missense_variant	2/3	ENST00000579755.2
CDKN2A	NM_000077.5	c.259C>A	p.Arg87=	synonymous_variant	2/3	ENST00000304494.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CDKN2A	ENST00000579755.2	c.302C>A	p.Pro101Gln	missense_variant	2/3	1	NM_058195.4
CDKN2A	ENST00000304494.10	c.259C>A	p.Arg87=	synonymous_variant	2/3	1	NM_000077.5	P2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1452390 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 722914

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 Cov.: 32

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

May 20, 2021

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. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site, but this prediction has not been confirmed by published transcriptional studies. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of p.Pro101Gln in p14ARF (SIFT: "Tolerated"; PolyPhen-2: "Unavailable"; Align-GVGD: "Class C0"). These predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has not been reported in the literature in individuals with CDKN2A-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change affects codon 87 of the CDKN2A (p16INK4a) mRNA. It is a 'silent' change, meaning that it does not change the encoded amino acid sequence of the CDKN2A (p16INK4a) protein. Alternatively, this sequence change replaces proline with glutamine at codon 101 of the p14ARF protein (p.Pro101Gln). The proline residue is moderately conserved and there is a moderate physicochemical difference between proline and glutamine. The CDKN2A gene encodes two different proteins, p16INK4a and p14ARF, which are translated from alternative transcripts that have different open reading frames. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Uncertain	0.084	D
BayesDel_noAF	Benign	-0.12
CADD	Benign	12
DANN	Uncertain	0.98
DEOGEN2	Benign	0.062	T;T
Eigen	Benign	0.096
Eigen_PC	Benign	0.19
FATHMM_MKL	Uncertain	0.77	D
M_CAP	Uncertain	0.12	D
MetaRNN	Benign	0.16	T;T
MetaSVM	Benign	-0.44	T
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D;D;N;N;N
Sift4G	Benign	0.20	T;T
Vest4		0.20
MVP		0.99
ClinPred		0.31	T
GERP RS		5.0

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr9-21971099;