4-54731903-A-T

Position:

• chr4-54731903-A-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 3P and 1B. PM2 PP2 BP4

The NM_000222.3(KIT):​c.2266A>T​(p.Ile756Phe) 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 benign outcome for this variant. 12/21 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. I756V) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: KIT NM_000222.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.18

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 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.
• BP4: Computational evidence support a benign effect (MetaRNN=0.27439117).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KIT	NM_000222.3	c.2266A>T	p.Ile756Phe	missense_variant	16/21	ENST00000288135.6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KIT	ENST00000288135.6	c.2266A>T	p.Ile756Phe	missense_variant	16/21	1	NM_000222.3	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Gastrointestinal stromal tumor Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 31, 2019

This variant has not been reported in the literature in individuals with KIT-related disease. ClinVar contains an entry for this variant (Variation ID: 409767). 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. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0"). This variant is not present in population databases (ExAC no frequency). This sequence change replaces isoleucine with phenylalanine at codon 756 of the KIT protein (p.Ile756Phe). The isoleucine residue is highly conserved and there is a small physicochemical difference between isoleucine and phenylalanine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Uncertain	0.062	T
BayesDel_noAF	Benign	-0.15
CADD	Benign	16
DANN	Benign	0.95
DEOGEN2	Uncertain	0.54	.;D
Eigen	Benign	-0.31
Eigen_PC	Benign	-0.27
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.91	D;D
M_CAP	Uncertain	0.093	D
MetaRNN	Benign	0.27	T;T
MetaSVM	Uncertain	-0.21	T
MutationAssessor	Benign	0.97	.;L
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.51	T
PROVEAN	Benign	-1.6	N;N
REVEL	Uncertain	0.39
Sift	Uncertain	0.014	D;D
Sift4G	Uncertain	0.033	D;D
Polyphen		0.66	P;P
Vest4		0.23
MutPred		0.49		.;Gain of glycosylation at T753 (P = 0.0222);
MVP		0.84
MPC		0.97
ClinPred		0.36	T
GERP RS		2.3
Varity_R		0.16
gMVP		0.75

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: rs779862483; hg19: chr4-55598069;