9-21974706-G-T

Variant names:

• chr9-21974706-G-T
• rs373407950
• NM_000077.5:c.122C>A

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 2P and 3B. PM1 BP4_Moderate BS1_Supporting

The NM_000077.5(CDKN2A):​c.122C>A​(p.Pro41Gln) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000372 in 1,612,890 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P41S) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000020 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: CDKN2A NM_000077.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:6 B:1
• Conservation: PhyloP100: -0.965
• Publications: 2 publications found

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 Gene-Disease associations (from GenCC):

• melanoma, cutaneous malignant, susceptibility to, 2

  Inheritance: AD Classification: DEFINITIVE Submitted by: G2P
• melanoma-pancreatic cancer syndrome

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Genomics England PanelApp, ClinGen, Labcorp Genetics (formerly Invitae), Ambry Genetics
• familial atypical multiple mole melanoma syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• melanoma and neural system tumor syndrome

  Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics

ENSG00000264545 (HGNC:):

ACMG classification

Our verdict: Likely_benign. The variant received -1 ACMG points.

• PM1: In a hotspot region, there are 7 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 42 uncertain in NM_000077.5
• BP4: Computational evidence support a benign effect (MetaRNN=0.1741842).
• BS1: Variant frequency is greater than expected in population eas. GnomAd4 allele frequency = 0.0000197 (3/152042) while in subpopulation EAS AF = 0.000581 (3/5166). AF 95% confidence interval is 0.000158. There are 0 homozygotes in GnomAd4. There are 2 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000077.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CDKN2A	NM_000077.5	MANE Select	c.122C>A	p.Pro41Gln	missense	Exon 1 of 3	NP_000068.1
	CDKN2A	NM_058195.4	MANE Plus Clinical	c.194-3498C>A		intron	N/A	NP_478102.2
	CDKN2A	NM_001195132.2		c.122C>A	p.Pro41Gln	missense	Exon 1 of 4	NP_001182061.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CDKN2A	ENST00000304494.10	TSL:1 MANE Select	c.122C>A	p.Pro41Gln	missense	Exon 1 of 3	ENSP00000307101.5
	CDKN2A	ENST00000498124.1	TSL:1	c.122C>A	p.Pro41Gln	missense	Exon 1 of 4	ENSP00000418915.1
	CDKN2A	ENST00000380151.3	TSL:1	n.122C>A		non_coding_transcript_exon	Exon 1 of 3	ENSP00000369496.3

Frequencies

GnomAD3 genomes AF: 0.0000197 AC: 3 AN: 152042 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000581

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000327 AC: 8 AN: 244752 AF XY: 0.0000150

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000439

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1460848 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 726730

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.0000756 AC: 3 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52542

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111888

Other (OTH) AF: 0.00 AC: 0 AN: 60356

GnomAD4 genome AF: 0.0000197 AC: 3 AN: 152042 Hom.: 0 Cov.: 32 AF XY: 0.0000269 AC XY: 2 AN XY: 74284

African (AFR) AF: 0.00 AC: 0 AN: 41384

American (AMR) AF: 0.00 AC: 0 AN: 15268

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.000581 AC: 3 AN: 5166

South Asian (SAS) AF: 0.00 AC: 0 AN: 4820

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10620

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 67998

Other (OTH) AF: 0.00 AC: 0 AN: 2090

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000302

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000116 AC: 1

ExAC AF: 0.0000412 AC: 5

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:6 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:1 Benign:1

Jan 27, 2023

Ambry Genetics

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This alteration is classified as benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity.

Oct 02, 2023

Color Diagnostics, LLC DBA Color Health

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This missense variant replaces proline with glutamine at codon 41 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). An experimental functional study has reported this variant was neutral in a cell proliferation assay (PMID: 35001868). This variant has not been reported in individuals affected with CDKN2A-related disorders in the literature. This variant has been identified in 9/276116 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.

Ovarian cancer Pathogenic:1

Jan 01, 2022

Laboratory of Molecular Epidemiology of Birth Defects, West China Second University Hospital, Sichuan University

Significance: Likely pathogenic

Review Status: flagged submission

Collection Method: clinical testing

not specified Uncertain:1

Apr 04, 2025

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

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: CDKN2A c.122C>A (p.Pro41Gln) results in a non-conservative amino acid change in the encoded protein sequence. Three of five in-silico tools predict a benign effect of the variant on protein function. The variant allele was found at a frequency of 3.3e-05 in 244752 control chromosomes, predominantly at a frequency of 0.00044 within the East Asian subpopulation in the gnomAD database. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.122C>A has been reported in the literature in individuals affected with pancreatic ductal adenocarcinoma, also in control subjects (Xu_2015, Yin_2022, Okawa_2023). These report(s) do not provide unequivocal conclusions about association of the variant with Cutaneous Malignant Melanoma . At least one publication reports experimental evidence evaluating an impact on protein function. These results showed no damaging effect of this variant by an in vitro cell proliferation assay (Kimura_2022). The following publications have been ascertained in the context of this evaluation (PMID: 27756164, 27960642, 28765326, 9166859, 35001868, 16818274, 18519632, 36243179, 7718873, 26104880, 35171259). ClinVar contains an entry for this variant (Variation ID: 141111). Based on the evidence outlined above, the variant was classified as uncertain significance.

Melanoma and neural system tumor syndrome Uncertain:1

Aug 06, 2023

Baylor Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

not provided Uncertain:1

Jan 23, 2023

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In silico analysis, which includes protein predictors and evolutionary conservation, supports that this variant does not alter protein structure/function; Published functional studies demonstrate neutral cell proliferation effects (Kimura et al., 2022); This variant is associated with the following publications: (PMID: 26104880, 35001868)

Melanoma and neural system tumor syndrome;C1835044:Melanoma, cutaneous malignant, susceptibility to, 2;C1838547:Melanoma-pancreatic cancer syndrome Uncertain:1

Oct 31, 2018

Fulgent Genetics, Fulgent Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Familial melanoma Uncertain:1

Dec 24, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces proline, which is neutral and non-polar, with glutamine, which is neutral and polar, at codon 41 of the CDKN2A (p16INK4a) protein (p.Pro41Gln). This variant is present in population databases (rs373407950, gnomAD 0.05%). This missense change has been observed in individual(s) with pancreatic ductal adenocarcinoma and acute lymphoblastic leukemia (PMID: 26104880, 35171259). ClinVar contains an entry for this variant (Variation ID: 141111). 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 disruptive. Experimental studies are conflicting or provide insufficient evidence to determine the effect of this variant on CDKN2A (p16INK4a) function (PMID: 35001868). 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 v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.19
BayesDel_addAF	Benign	-0.21	T
BayesDel_noAF	Benign	-0.21
CADD	Benign	14
DANN	Benign	0.96
DEOGEN2	Benign	0.11	T
Eigen	Benign	-0.84
Eigen_PC	Benign	-1.1
FATHMM_MKL	Benign	0.22	N
LIST_S2	Benign	0.78	T
M_CAP	Pathogenic	0.50	D
MetaRNN	Benign	0.17	T
MetaSVM	Benign	-0.46	T
PhyloP100		-0.96
PrimateAI	Benign	0.46	T
PROVEAN	Benign	-1.7	N
REVEL	Uncertain	0.49
Sift	Benign	0.48	T
Sift4G	Benign	0.66	T
Polyphen		0.95	P
Vest4		0.19
MVP		0.97
MPC		1.0
ClinPred		0.28	T
GERP RS		-3.8
PromoterAI		-0.062	Neutral
Varity_R		0.054
gMVP		0.84
Mutation Taster		=56/44	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs373407950; hg19: chr9-21974705;