chr9-21970947-T-C

Position:

chr9-21970947-T-C

Variant summary

Our verdict is Likely benign. Variant got -6 ACMG points: 2P and 8B. PM1BP4_StrongBS2

The NM_000077.5(CDKN2A):c.412A>G(p.Arg138Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000093 in 1,612,210 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/20 in silico tools predict 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. R138T) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000089 ( 0 hom. )

Consequence

CDKN2A
NM_000077.5 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:5

Conservation

PhyloP100: 1.24

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:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_benign. Variant got -6 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

BP4

Computational evidence support a benign effect (MetaRNN=0.06717354).

BS2

High AC in GnomAdExome4 at 13 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CDKN2A	NM_000077.5 linkuse as main transcript	c.412A>G	p.Arg138Gly	missense_variant	2/3	ENST00000304494.10	NP_000068.1
CDKN2A	NM_058195.4 linkuse as main transcript	c.*56A>G		3_prime_UTR_variant	2/3	ENST00000579755.2	NP_478102.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CDKN2A	ENST00000304494.10 linkuse as main transcript	c.412A>G	p.Arg138Gly	missense_variant	2/3	1	NM_000077.5	ENSP00000307101	P2	P42771-1
CDKN2A	ENST00000579755.2 linkuse as main transcript	c.*56A>G		3_prime_UTR_variant	2/3	1	NM_058195.4	ENSP00000462950		Q8N726-1

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152242

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.00000812

AC:

AN:

246242

Hom.:

AF XY:

0.0000149

AC XY:

AN XY:

133924

show subpopulations

Gnomad AFR exome

AF:

0.00

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:

0.0000181

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000890

AC:

AN:

1459968

Hom.:

Cov.:

AF XY:

0.0000124

AC XY:

AN XY:

726338

show subpopulations

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:

0.0000117

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152242

Hom.:

Cov.:

AF XY:

0.0000134

AC XY:

AN XY:

74382

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:

0.0000147

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.0000113

ESP6500AA

AF:

0.00

AC:

ESP6500EA

AF:

0.000233

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Hereditary cancer-predisposing syndrome

Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Color Diagnostics, LLC DBA Color Health	Jul 07, 2022	The CDKN2A locus encodes two different gene products, p16INK4a and p14ARF (https://www.ncbi.nlm.nih.gov/books/NBK7030/). This missense variant replaces arginine with glycine at codon 138 of the CDKN2A (p16INK4A) protein. Computational prediction suggests that this variant may not impact protein structure and function (internally defined REVEL score threshold <= 0.5, PMID: 27666373). A functional study has shown that this variant does not alter CDKN2A (p16INK4A) protein function as determined by cell growth assay and its effect on CDK4/6-RB-E2F2 signaling pathway (PMID: 34369425). This variant has been reported in individuals affected with childhood-onset acute lymphoblastic leukemia (PMID: 26104880) and in an individual affected with melanocytic nevi without personal or a family history of melanoma (PMID: 11511321). This variant has been identified in 2/246242 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. -
Uncertain significance, criteria provided, single submitter	clinical testing	Ambry Genetics	Oct 31, 2023	The p.R138G variant (also known as c.412A>G), located in coding exon 2 of the CDKN2A gene, results from an A to G substitution at nucleotide position 412. The arginine at codon 138 is replaced by glycine, an amino acid with dissimilar properties. This alteration has been reported in an individual with acute lymphoblastic leukemia (Xu H et al. Nat Commun, 2015 Jun;6:7553). This amino acid position is poorly conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

not specified

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Jan 19, 2023

Variant summary: CDKN2A c.412A>G (p.Arg138Gly) results in a non-conservative amino acid change located in the ANK repeat 4 (CKB) of the encoded protein sequence. Four of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 8.1e-06 in 246242 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance c.412A>G has been reported in the literature in an individual with benign nevi, who had no personal or family history of melanoma (Welch_2001), and was also reported in a child affected with acute lymphoblastic leukemia, however it was also found in controls (Xu_2015). These reports do not provide unequivocal conclusions about association of the variant with Cutaneous Malignant Melanoma. At least one publication reports R138G suppresses IL3-independent growth similar to wild-type in BCR-ABL1-expressing cells in culture (Li_2022). Four ClinVar submitters (evaluation after 2014) cite the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Jun 28, 2023

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant does not alter protein structure/function; Published functional studies demonstrate protein levels and phosphorylation levels of CDK4 and Rb proteins comparable to wild-type (Li et al., 2022); This variant is associated with the following publications: (PMID: 26104880, 8573142, 27756164, 30857943, 27960642, 18519632, 16818274, 9166859, 28765326, 7718873, 34369425, 11511321, 30395287) -

Familial melanoma

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 24, 2024

This sequence change replaces arginine, which is basic and polar, with glycine, which is neutral and non-polar, at codon 138 of the CDKN2A (p16INK4a) protein (p.Arg138Gly). This variant is present in population databases (rs145012438, gnomAD 0.0009%). This missense change has been observed in individual(s) with dysplastic nevi that did not have a personal and family history of melanoma and acute lymphoblastic leukaemia (PMID: 11511321, 26104880). ClinVar contains an entry for this variant (Variation ID: 233990). Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Not Available"; PolyPhen-2: "Benign"; Align-GVGD: "Not Available". The glycine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect protein function. Experimental studies have shown that this missense change does not substantially affect CDKN2A (p16INK4a) function (PMID: 34369425). 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

0.061

BayesDel_addAF

Benign

-0.081

BayesDel_noAF

Benign

-0.35

CADD

Benign

DANN

Benign

0.62

DEOGEN2

Benign

0.075

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

Eigen

Benign

-1.3

Eigen_PC

Benign

-1.3

FATHMM_MKL

Benign

0.017

LIST_S2

Benign

0.58

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

M_CAP

Benign

0.035

MetaRNN

Benign

0.067

T;T;T;T;T;T;T

MetaSVM

Benign

-1.0

MutationTaster

Benign

1.0

N;N;N;N;N;N;N;N;N;N;N;N

PrimateAI

Benign

0.36

PROVEAN

Benign

-0.85

N;.;N;.;.;.;.

REVEL

Benign

0.22

Sift

Benign

0.33

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

Sift4G

Benign

0.36

T;T;T;T;T;T;T

Polyphen

0.0

B;.;.;.;.;.;.

Vest4

0.097

MVP

0.60

MPC

0.50

ClinPred

0.042

GERP RS

-1.5

Varity_R

0.044

gMVP

0.43

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.010

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