A Novel Frameshift Mutation in the ITGB3 Gene Leading to Glanzmann's Thrombasthenia in a Saudi Arabian Family.

Glanzmann's thrombasthenia (GT) is an autosomal recessive congenital bleeding disorder of platelet aggregation. Mutations in ITGA2B and ITGB3 genes result in quantitative and/or qualitative abnormalities of the glycoprotein receptor complex IIb/IIIa (integrin αIIbβ3), which in turn impairs platelet aggregation and lead to GT. In this study, whole genome single nucleotide polymorphism (SNP) genotyping as well as whole exome sequencing was performed in a large family segregating GT. Analysis of the genotypes localized the disease region to chromosome 17q21.2-q21.3. Filtration of whole exome data and candidate variants prioritization identified a pathogenic variant in the ITGB3 gene. The single nucleotide deletion variant (c.2113delC) in exon 13 of the ITGB3 gene is predicted to cause a frameshift and absence of vital C-terminal domains including the transmembrane helix and the cytoplasmic domain. Clinical variability of the bleeding phenotype in affected individuals with the same mutation suggests that other genetic and nongenetic factors are responsible for determining GT features.