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 to traditional diagnostic approaches, Next-generation sequencing (NGS) offers comprehensive detection of known and novel variants, enhancing diagnostic accuracy in genetic 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 selected novel variants. Results: A total of 21 distinct variants were identified (15 in ITGA2B and 6 in ITGB3), achieving an 87.3% diagnostic yield. Ten were novel, including missense, frameshift, splice-site, and CNV variants. 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.