rs202052259

chr4-54703877-A-G

Variant summary

Our verdict is Benign. Variant got -8 ACMG points: 1P and 9B. PP2 BP4_Strong BS1_Supporting BS2

The NM_000222.3(KIT):c.910A>G(p.Thr304Ala) variant causes a missense change. The variant allele was found at a frequency of 0.000136 in 1,613,514 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. T304T) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.000092 (0 hom., cov: 32)
  • Exomes 𝑓: 0.00014 (0 hom.)
• Consequence: KIT NM_000222.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:5 B:3
• Conservation: PhyloP100: 4.17

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 Benign. Variant got -8 ACMG points.

• PP2: Missense variant where missense usually causes diseases, KIT
• BP4: Computational evidence support a benign effect (MetaRNN=0.022070289).
• BS1: Variant frequency is greater than expected in population eas. gnomad4_exome allele frequency = 0.00014 (205/1461190) while in subpopulation EAS AF= 0.00502 (199/39674). AF 95% confidence interval is 0.00444. There are 0 homozygotes in gnomad4_exome. There are 99 alleles in male gnomad4_exome subpopulation. Median coverage is 31. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting
• BS2: High AC in GnomAd at 14 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KIT	NM_000222.3	c.910A>G	p.Thr304Ala	missense_variant	5/21	ENST00000288135.6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KIT	ENST00000288135.6	c.910A>G	p.Thr304Ala	missense_variant	5/21	1	NM_000222.3	P4

Frequencies

GnomAD3 genomes AF: 0.0000920 AC: 14 AN: 152206 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00250

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

GnomAD3 exomes AF: 0.000207 AC: 52 AN: 251326 Hom.: 0 AF XY: 0.000162 AC XY: 22 AN XY: 135840

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000289

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00277

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.000140 AC: 205 AN: 1461190 Hom.: 0 Cov.: 31 AF XY: 0.000136 AC XY: 99 AN XY: 726978

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000447

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00502

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.00e-7

Gnomad4 OTH exome AF: 0.0000497

GnomAD4 genome AF: 0.0000919 AC: 14 AN: 152324 Hom.: 0 Cov.: 32 AF XY: 0.000107 AC XY: 8 AN XY: 74490

Gnomad4 AFR AF: 0.0000241

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00251

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000499 Hom.: 0

Bravo AF: 0.0000756

ExAC AF: 0.000198 AC: 24

Asia WGS AF: 0.00144 AC: 5 AN: 3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:5 Benign:3

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Gastrointestinal stromal tumor Uncertain:1 Benign:2

Uncertain significance, criteria provided, single submitter	clinical testing	St. Jude Molecular Pathology, St. Jude Children's Research Hospital	Jul 05, 2022	The KIT c.910A>G (p.Thr304Ala) missense change has a maximum frequency of 0.28% in gnomAD v2.1.1 (https://gnomad.broadinstitute.org/). The in silico tool REVEL is inconclusive about a pathogenic or benign effect of this variant on protein function, and to our knowledge functional studies have not been performed. This variant has been reported in an individual with piebaldism who harbored a second missense variant in KIT however it was not known if the variants were on the same or opposite alleles (PMID: 25176472). To our knowledge, this variant has not been reported in individuals with gastrointestinal stromal tumor. In summary, the evidence currently available is insufficient to determine the clinical significance of this variant. It has therefore been classified as of uncertain significance. -
Likely benign, criteria provided, single submitter	clinical testing	Invitae	Jan 21, 2024	- -
Likely benign, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 12, 2018	This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Hereditary cancer-predisposing syndrome Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Ambry Genetics	May 21, 2019	The p.T304A variant (also known as c.910A>G), located in coding exon 5 of the KIT gene, results from an A to G substitution at nucleotide position 910. The threonine at codon 304 is replaced by alanine, an amino acid with similar properties. This alteration was seen in a patient with piebaldism who was also positive for another alteration in the KIT gene, p.E583D (Lee H et al. J. Dermatol. Sci., 2014 Oct;76:74-6). This amino acid position is highly conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -
Uncertain significance, criteria provided, single submitter	curation	Sema4, Sema4	May 18, 2021	- -

Ovarian cancer Pathogenic:1

Likely pathogenic, flagged submission

clinical testing

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

Jan 01, 2022

- -

Piebaldism Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

not provided Uncertain:1

Uncertain significance, no assertion criteria provided

research

Biesecker Lab/Clinical Genomics Section, National Institutes of Health

Jul 13, 2012

- -

Mastocytosis Benign:1

Benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as benign is not then subjected to further curation. The score for this variant resulted in a classification of benign for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.093
BayesDel_addAF	Benign	-0.13	T
BayesDel_noAF	Uncertain	0.030
Cadd	Benign	21
Dann	Uncertain	1.0
Eigen	Uncertain	0.51
Eigen_PC	Uncertain	0.55
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Benign	0.59	T;T
M_CAP	Benign	0.051	D
MetaRNN	Benign	0.022	T;T
MetaSVM	Uncertain	0.39	D
MutationAssessor	Uncertain	2.4	M;M
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.53	T
PROVEAN	Benign	-1.8	N;N
REVEL	Uncertain	0.53
Sift	Benign	0.52	T;T
Sift4G	Benign	0.50	T;T
Polyphen		0.78	P;D
Vest4		0.42
MVP		0.86
MPC		0.69
ClinPred		0.094	T
GERP RS		5.9
Varity_R		0.12
gMVP		0.90

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.060		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: rs202052259; hg19: chr4-55570043; COSMIC: COSV55399408;