Novel/Recurrent Variants in Pakistani Glanzmann Thrombasthenia and Glanzmann-like Bleeding Diathesis: Insights from NGS Analysis.

INTRODUCTION

Glanzmann thrombasthenia (GT) and GT-like phenotype represent inherited platelet disorders caused by defects in platelet glycoprotein αIIbβ3 (encoded by ITGA2B and ITGB3) or RASGRP2- and FERMT3-mediated platelet intracellular signaling, respectively. While globally rare, prevalence of these bleeding phenotypes is notably higher in regions with high consanguinity, including Pakistan, with limited data on GT-associated variants. Compared with traditional diagnostic approaches, next-generation sequencing (NGS) offers comprehensive detection of known and novel variants, enhancing diagnostic accuracy in genetically heterogeneous disorders like GT.

METHODS

This study investigated the mutational spectrum of GT and GT-like phenotype in 67 patients from 55 unrelated Pakistani families using a targeted gene panel. Variant annotation and pathogenicity assessments were performed using established guidelines. Structural modeling and molecular dynamics simulations were used to predict the functional consequences of select novel variants.

RESULTS

A total of 21 distinct variants were identified (15 in ITGA2B and 6 in ITGB3), achieving an 87.3% diagnostic yield. In all, 10 were novel, including missense, frameshift, splice-site, and copy number variants (CNVs). Two recurrent ITGA2B frameshift variants suggested possible founder effect. Analysis of RASGRP2 revealed two novel homozygous variants in GT-like cases. A genotype-phenotype association analyses suggested a severe bleeding diathesis in GT patients harboring truncating mutations in an age-dependent manner, and clinical diversity among GT patients with same genetic variant.

CONCLUSION

This study expands the mutational spectrum of GT and GT-like bleeding diathesis in Pakistani population, identifying novel and recurrent mutations, which highlights the diagnostic value of NGS.