chr9-21970925-A-G

Variant names:

• chr9-21970925-A-G
• rs730881680
• NM_000077.5:c.434T>C

Variant summary

Our verdict is Likely benign. The variant received -4 ACMG points: 2P and 6B. PM1 BP4_Moderate BS2

The NM_000077.5(CDKN2A):​c.434T>C​(p.Ile145Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000479 in 1,460,132 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/21 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. I145L) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000048 (0 hom.)
• Consequence: CDKN2A NM_000077.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:5 B:1
• Conservation: PhyloP100: -2.46
• Publications: 5 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 -4 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 7 benign, 42 uncertain in NM_000077.5
• BP4: Computational evidence support a benign effect (MetaRNN=0.08194688).
• BS2: High AC in GnomAdExome4 at 7 AD gene.

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.434T>C	p.Ile145Thr	missense	Exon 2 of 3	NP_000068.1
	CDKN2A	NM_058195.4	MANE Plus Clinical	c.*78T>C		3_prime_UTR	Exon 2 of 3	NP_478102.2
	CDKN2A	NM_001195132.2		c.434T>C	p.Ile145Thr	missense	Exon 2 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.434T>C	p.Ile145Thr	missense	Exon 2 of 3	ENSP00000307101.5
	CDKN2A	ENST00000498124.1	TSL:1	c.434T>C	p.Ile145Thr	missense	Exon 2 of 4	ENSP00000418915.1
	CDKN2A	ENST00000380151.3	TSL:1	n.*357T>C		non_coding_transcript_exon	Exon 2 of 3	ENSP00000369496.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000479 AC: 7 AN: 1460132 Hom.: 0 Cov.: 31 AF XY: 0.00000688 AC XY: 5 AN XY: 726422

African (AFR) AF: 0.00 AC: 0 AN: 33462

American (AMR) AF: 0.0000224 AC: 1 AN: 44720

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: 86230

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52186

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5364

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1112002

Other (OTH) AF: 0.0000497 AC: 3 AN: 60332

GnomAD4 genome Cov.: 32

ClinVar

ClinVar submissions as Germline

Significance: Conflicting classifications of pathogenicity

Revision: criteria provided, conflicting classifications

Pathogenic	VUS	Benign	Condition
-	2	1	Hereditary cancer-predisposing syndrome (3)
-	1	-	Familial melanoma (1)
-	1	-	not provided (1)
-	1	-	not specified (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.12
BayesDel_addAF	Benign	-0.16	T
BayesDel_noAF	Benign	-0.47
CADD	Benign	0.040
DANN	Benign	0.30
DEOGEN2	Benign	0.062	T
Eigen	Benign	-1.4
Eigen_PC	Benign	-1.3
FATHMM_MKL	Benign	0.0059	N
LIST_S2	Benign	0.44	T
M_CAP	Benign	0.017	T
MetaRNN	Benign	0.082	T
MetaSVM	Benign	-1.0	T
PhyloP100		-2.5
PrimateAI	Benign	0.42	T
PROVEAN	Benign	0.13	N
REVEL	Benign	0.15
Sift	Benign	0.91	T
Sift4G	Benign	0.79	T
Polyphen		0.0	B
Vest4		0.095
MutPred		0.29		Gain of glycosylation at I145 (P = 0.0123)
MVP		0.66
MPC		0.49
ClinPred		0.021	T
GERP RS		2.1
PromoterAI		0.0074	Neutral
Varity_R		0.022
gMVP		0.31
Mutation Taster		=39/61	disease causing

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

Other links and lift over

dbSNP: rs730881680; hg19: chr9-21970924;