β2 Integrin Gene (ITGB2) mutation spectra in Pakistani families with leukocyte adhesion deficiency type 1 (LAD1)

Leukocyte adhesion deficiency I (LADI) is an autosomal recessive type of primary immunodeficiency characterized by occurrence of repeated bacterial infections, impaired pus formation and wound healing. Genetic variations in the β-2 integrin subunit encoding gene ITGB2 have been implicated in causing the disorder. In the present study, we have investigated twelve patients presenting LAD1 features. After collecting clinical and family history, flow cytometry was used to determine levels of CD18 in the patients. Clinical history revealed that umbilical cord separation occurred mostly after 19 days in the patients. Recurrent skin infections were found in seven patients. Eight patients had at least one elder sibling who died due to repeated infections. All patients had marked neutrophilia with only 0.77% of neutrophils expressing CD18. Total 12 patients suffering from LAD1 were Sanger sequenced for ITGB2 gene. Five variants, including a novel p.(Cys286Phe) and four previously reported [p.(Gly273Arg), p.(Asp128Tyr), p.(Cys62*), IVS7 + 1G > A] were identified in 8 cases, while no pathogenic variant was observed in remaining four cases. This study represents the first comprehensive clinical and genetic characterization of LAD1 in Pakistani population. This will facilitate diagnosis and genetic counselling of patients with immunodeficiency disorders in Pakistani population.