chr9-21968229-T-G

Position:

• chr9-21968229-T-G

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PM4

The NM_000077.5(CDKN2A):​c.471A>C​(p.Ter157CysextTer13) variant causes a stop lost 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 (★). Synonymous variant affecting the same amino acid position (i.e. *157*) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: CDKN2A NM_000077.5 stop_lost
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -0.545

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.

• PM2: Very rare variant in population databases, with high coverage
• PM4: Stoplost variant in NM_000077.5 Downstream stopcodon found after 39 codons.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CDKN2A	NM_000077.5	c.471A>C	p.Ter157CysextTer13	stop_lost	3/3	ENST00000304494.10
CDKN2A	NM_058195.4	c.*115A>C		3_prime_UTR_variant	3/3	ENST00000579755.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CDKN2A	ENST00000304494.10	c.471A>C	p.Ter157CysextTer13	stop_lost	3/3	1	NM_000077.5	P2
CDKN2A	ENST00000579755.2	c.*115A>C		3_prime_UTR_variant	3/3	1	NM_058195.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 27, 2019

The c.471A>C variant (also known as p.*157Cext*13), located in coding exon 3 of the CDKN2A gene, results from an A to C substitution at nucleotide position 471, which is the last nucleotide of the CDKN2A gene. The stop codon at position 157 is replaced by Cysteine, resulting in an elongation of the protein by 13 amino acids. The exact functional impact of these inserted amino acids is unknown at this time. This nucleotide position is well conserved in available vertebrate species. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Uncertain	0.043	T
BayesDel_noAF	Benign	-0.18
CADD	Benign	0.59
DANN	Benign	0.56
DEOGEN2	Benign	0.0062	T
Eigen	Benign	-0.69
Eigen_PC	Benign	-0.90
FATHMM_MKL	Benign	0.14	N
LIST_S2	Benign	0.26	T
MetaRNN	Benign	0.13	T
MutationTaster	Benign	1.0	N;N;N;N;N;N;N;N;N
Sift4G	Benign	0.34	T
Vest4		0.13
MVP		0.86
GERP RS		0.029

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: rs1587325182; hg19: chr9-21968228;