Table1_Molecular and hematological studies in a cohort of beta zero South East Asia deletion (β°-thal SEA) from Malaysian perspective.docx

AbstractWe report the haematological parameters and molecular characterization of beta zero (β°) South East Asia (SEA) deletion in the HBB gene cluster with unusually high levels of Hb F compared to a classical heterozygous beta zero (β°)-thalassaemia.MethodsRetrospective study on 17 cases of (β°) South East Asia (SEA) deletion from 2016 to 2019 referred to Institute for Medical Research were conducted. The clinical information and haematological profiles were evaluated. The mutation was analyzed, and the results were compared with other β°-thalassaemia groups. For HBB gene genotyping, all the cases were subjected for multiplex gap-PCR, 5 cases were subjected for HBB gene sequencing for exclusion of compound heterozygous with other beta variants. Co-inheritance of α-thalassaemia were determined using multiplex gap-PCR and multiplex ARMS-PCR.ResultsSeventeen cases were positive for β°-thal SEA deletion. Fifteen cases were heterozygous and two were compound heterozygous for β°-thal SEA deletion. The results were compared with 182 cases of various heterozygous β° deletions and mutations. The mean Hb for heterozygous β°-thal SEA deletion (13.44 ± 1.45 g/dl) was normal and significantly higher than heterozygous IVS 1-1 and Codon 41/42 (post hoc test, p ConclusionWe conclude that β°-thal SEA deletion has a unique haematological parameters of beta zero thalassaemia trait. We affirm to classifying this deletion as SEA-HPFH based on previous studies considering the phenotype features rather than the molecular defect of β°-thal SEA deletion, as this will make it easier to offer genetic counselling to affected individuals.