A Novel 5 kb Deletion in the β-Globin Gene Cluster Identified in a Chinese Patient

Abstract

β-Thalassemia (β-thal), a highly prevalent disease in tropical and subtropical regions of Southern China, is caused mainly by point mutations in the β-globin gene cluster. However, large deletions have also been found to contribute to some types of β-thal. We identified a novel 5 kb deletion in the β-globin cluster in a Chinese patient using multiplex ligation-dependent probe amplification (MLPA), and characterized it with single molecule real-time (SMRT) sequencing, gap-polymerase chain reaction (gap-PCR) and Sanger sequencing. The deletion was located between positions 5226189 and 5231091 on chromosome 11 (GRCh38), extending from 4 kb upstream of the 5' untranslated region (5'UTR) to the second intron of the β-globin gene. The patient with this deletion presented with microcytosis and hypochromic red cells, as well as relatively high Hb F and Hb A2 levels. Our research indicated that SMRT sequencing is a useful tool for accurate detection of large deletions. Our study broadens the spectrum of deletional β-thalassemias and provides a perspective for further study of the function of the β-globin cluster.