4-54703796-A-C

Position:

• chr4-54703796-A-C

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 3P and 2B. PM2 PP2 BP4_Moderate

The NM_000222.3(KIT):​c.829A>C​(p.Ile277Leu) 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. 14/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: KIT NM_000222.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 1.85

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 Uncertain_significance. Variant got 1 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=0.25399065).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KIT	NM_000222.3	c.829A>C	p.Ile277Leu	missense_variant	5/21	ENST00000288135.6	NP_000213.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KIT	ENST00000288135.6	c.829A>C	p.Ile277Leu	missense_variant	5/21	1	NM_000222.3	ENSP00000288135.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251290 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135804

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000327

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 6.84e-7 AC: 1 AN: 1461272 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 726990

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Gastrointestinal stromal tumor Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

May 03, 2023

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. 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 tolerated. ClinVar contains an entry for this variant (Variation ID: 966337). This variant has not been reported in the literature in individuals affected with KIT-related conditions. This variant is present in population databases (rs757547974, gnomAD 0.003%). This sequence change replaces isoleucine, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 277 of the KIT protein (p.Ile277Leu). -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Sep 01, 2024

The p.I277L variant (also known as c.829A>C), located in coding exon 5 of the KIT gene, results from an A to C substitution at nucleotide position 829. The isoleucine at codon 277 is replaced by leucine, an amino acid with highly similar properties. This amino acid position is conserved. In addition, this alteration is predicted to be tolerated by in silico analysis. Based on the available evidence, the clinical significance of this variant remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.14
BayesDel_addAF	Benign	-0.24	T
BayesDel_noAF	Benign	-0.48
CADD	Benign	16
DANN	Benign	0.93
DEOGEN2	Benign	0.25	.;T
Eigen	Benign	-0.63
Eigen_PC	Benign	-0.60
FATHMM_MKL	Benign	0.74	D
LIST_S2	Benign	0.74	T;T
M_CAP	Benign	0.0082	T
MetaRNN	Benign	0.25	T;T
MetaSVM	Benign	-1.1	T
MutationAssessor	Uncertain	2.5	M;M
PrimateAI	Benign	0.39	T
PROVEAN	Benign	-1.0	N;N
REVEL	Benign	0.058
Sift	Benign	0.42	T;T
Sift4G	Benign	0.41	T;T
Polyphen		0.027	B;B
Vest4		0.41
MutPred		0.66		Gain of sheet (P = 0.0827);Gain of sheet (P = 0.0827);
MVP		0.43
MPC		0.45
ClinPred		0.12	T
GERP RS		0.69
Varity_R		0.092
gMVP		0.99

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: rs757547974; hg19: chr4-55569962;