4-54728096-T-G

Position:

• chr4-54728096-T-G

Variant summary

Our verdict is Pathogenic. Variant got 13 ACMG points: 13P and 0B. PM2 PP2 PP3_Moderate PP5_Very_Strong

The NM_000222.3(KIT):​c.1965T>G​(p.Asn655Lys) 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 pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: KIT NM_000222.3 missense
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 1.12

Genes affected

KIT (HGNC:6342): (KIT proto-oncogene, receptor tyrosine kinase) This gene encodes a receptor tyrosine kinase. This gene was initially identified as a homolog of the feline sarcoma viral oncogene v-kit and is often referred to as proto-oncogene c-Kit. The canonical form of this glycosylated transmembrane protein has an N-terminal extracellular region with five immunoglobulin-like domains, a transmembrane region, and an intracellular tyrosine kinase domain at the C-terminus. Upon activation by its cytokine ligand, stem cell factor (SCF), this protein phosphorylates multiple intracellular proteins that play a role in in the proliferation, differentiation, migration and apoptosis of many cell types and thereby plays an important role in hematopoiesis, stem cell maintenance, gametogenesis, melanogenesis, and in mast cell development, migration and function. This protein can be a membrane-bound or soluble protein. Mutations in this gene are associated with gastrointestinal stromal tumors, mast cell disease, acute myelogenous leukemia, and piebaldism. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, May 2020]

KIT (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 13 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), KIT. . Gene score misZ 2.5806 (greater than the threshold 3.09). Trascript score misZ 4.1549 (greater than threshold 3.09). GenCC has associacion of gene with piebaldism, gastrointestinal stromal tumor, mastocytosis, cutaneous mastocytosis.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.935
• PP5: Variant 4-54728096-T-G is Pathogenic according to our data. Variant chr4-54728096-T-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 375924.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KIT	NM_000222.3	c.1965T>G	p.Asn655Lys	missense_variant	13/21	ENST00000288135.6	NP_000213.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KIT	ENST00000288135.6	c.1965T>G	p.Asn655Lys	missense_variant	13/21	1	NM_000222.3	ENSP00000288135.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Gastrointestinal stromal tumor Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 03, 2019

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. 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. In an experimental study, this missense change lead to constitutive autophosphorylation of KIT, which was inhibited by imatinib (PMID: 17489795). This missense change has been reported in a melanoma and a gastrointestinal stromal tumor (GIST), however it is not known whether this variant was of germline or somatic origin (PMID: 21569090, 17489795). This missense change was also observed in an individual with GIST and cutaneous mastocytosis (Invitae) and segregates with GIST in a family (Invitae). ClinVar contains an entry for this variant (Variation ID: 375924). This variant is not present in population databases (ExAC no frequency). This sequence change replaces asparagine with lysine at codon 655 of the KIT protein (p.Asn655Lys). The asparagine residue is highly conserved and there is a moderate physicochemical difference between asparagine and lysine. -

Hereditary cancer-predisposing syndrome Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

May 07, 2024

The p.N655K variant (also known as c.1965T>G), located in coding exon 13 of the KIT gene, results from a T to G substitution at nucleotide position 1965. The asparagine at codon 655 is replaced by lysine, an amino acid with similar properties. This variant was reported in multiple individuals with features consistent with KIT-related gastrointestinal stromal tumor syndrome (Fornasarig M et al. J Pers Med, 2020 Nov;10; Ingley KM et al. NPJ Genom Med, 2024 Mar;9:24; External communication). A protein functional study demonstrated this variant to result in autophosphorylation and to be sensitive to kinase inhibitors (Kinoshita K et al. Am J Gastroenterol, 2007 May;102:1134-6). This amino acid position is highly conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Uncertain	0.080	D
BayesDel_noAF	Benign	-0.12
CADD	Benign	22
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.80	.;D
Eigen	Benign	-0.14
Eigen_PC	Benign	-0.18
FATHMM_MKL	Uncertain	0.83	D
LIST_S2	Uncertain	0.95	D;D
M_CAP	Pathogenic	0.43	D
MetaRNN	Pathogenic	0.94	D;D
MetaSVM	Uncertain	-0.055	T
MutationAssessor	Benign	-0.065	.;N
PrimateAI	Pathogenic	0.83	D
PROVEAN	Pathogenic	-5.5	D;D
REVEL	Uncertain	0.59
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0	D;D
Polyphen		1.0	D;D
Vest4		0.98
MutPred		0.74		.;Gain of sheet (P = 0.0125);
MVP		0.92
MPC		1.4
ClinPred		1.0	D
GERP RS		-0.33
Varity_R		0.97
gMVP		0.92

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: rs1057519708; hg19: chr4-55594262; COSMIC: COSV55400316; COSMIC: COSV55400316;