Prenatal Diagnosis and Screening of Thalassemia Mutations in Bangladesh: Presence of Rare Mutations.

Thalassemia is the most common congenital monogenic disorder in Bangladesh. Prenatal diagnosis (PND) and pregnation termination of an affected child is one of the best options to reduce the burden of thalassemic children. This article reports the results of DNA analyses of chorionic villus sampling (CVS) and amniocentesis of fetuses of mothers who came to the thalassemia center of Dhaka Shishu (Children) Hospital, Dhaka, Bangladesh. DNA analysis was done by real-time polymerase chain reaction (qPCR) and Sanger sequencing. Maternal contamination was ruled out by variable number of tandem repeats (VNTRs). A total of 232 samples were analyzed. Hb E (HBB: c.79G>A)/ß-thalassemia (Hb E/ß-thal) was the most common type of thalassemia seen in 32 samples (13.79%) followed by ß-thal major (ß-TM) in 10 cases (4.31%). Molecular characterization of the most predominant mutation was IVS-I-5 (G>A) (HBB: c.92+5G>C). The analysis also revealed five rare mutations: IVS-II-654 (C>T) (HBB: c.316-197C>T), IVS-II-1 (G>A) (HBB: c.315+5G>A), codon 44 (-C) (HBB: c.135delC), -86 (C>A) (HBB: c.-136C>A) and codons 14/15 (+G) (HBB: c.45_46insG), which have not been reported previously in Bangladesh. This study provides important information for PND and will help in the development of similar diagnostic programs for other DNA centers in Bangladesh.

Impaired acylcarnitine profile in transfusion-dependent beta-thalassemia major patients in Bangladesh.

Patients with beta-thalassemia major (BTM) suffer from fatigue, poor physical fitness, muscle weakness, lethargy, and cardiac complications which are related to an energy crisis. Carnitine and acylcarnitine derivatives play important roles in fatty acid oxidation, and deregulation of carnitine and acylcarnitine metabolism may lead to an energy crisis. The present study aimed to investigate carnitine and acylcarnitine metabolites to gain an insight into the pathophysiology of BTM. Dried blood spots of 45 patients with BTM and 96 age-matched healthy controls were analyzed for free carnitine and 24 acylcarnitines by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Although medium chain acylcarnitine levels were similar in the patients with BTM and healthy controls, free carnitine, short chain acylcarnitines, long chain acylcarnitines, and total acylcarnitine levels were significantly lower in patients with BTM than in the healthy controls (P < 0.05). Moreover, an impaired fatty acid oxidation rate was observed in the patients with BTM, as manifested by decreased fatty acid oxidation indicator ratios, namely C2/C0 and (C2 + C3)/C0. Furthermore, an increase in the C0/(C16 + C18) ratio indicated reduced carnitine palmitoyltransferase-1 (CPT-1) activity in the patients with BTM compared with that in the healthy controls. Thus, a low level of free carnitine and acylcarnitines together with impaired CPT-1 activity contribute to energy crisis-related complications in the patients with BTM.

A Novel ß-Thalassemia Insertion/Frameshift Mutation Between Codons 77/78 (p.Leu78Profs*13 or HBB: c.235_236insC) Observed in a Family in Bangladesh.

ß-Thalassemia (ß-thal) is one of the most common inherited hemoglobin (Hb) disorders, worldwide. A 28-year-old female and her husband came to Dhaka Shishu (Children) Hospital, Bangladesh for prenatal diagnosis for thalassemia mutations. We identified and characterized a novel ß-thalassemia (ß-thal) mutation due to an insertion of cytosine between codons 77 and 78 (p.Leu78Profs*13) found in mother in a heterozygous state. This mutation caused an insertion in the normal reading frame of the ß-globin coding sequence and the new stop codon being the amino acid 90 (HBB: c.235_236insC) in exon 2 that leads to a ß0-thal phenotype.