A Perspective on Thalassaemia

A Pragmatic Scoring Tool to Predict Hydroxyurea Response Among β-Thalassemia Major Patients in Pakistan

Despite high prevalence and incidence of β-thalassemia in Pakistan, there is very limited work on the use of hydroxyurea (HU) in thalassemia patients in the country. This is the first insight regarding genetic profiling of BCL11A and HU responses in Pakistani β-thalassemia. It correlates single-nucleotide polymorphisms on BCL11A (rs4671393, rs766432) and HBG2 (XmnI), age at first transfusion, and β-globin mutations with HU response in β-thalassemia major (BTM). Of 272 patients treated with HU, 98 were complete responders, 55 partial responders, and 119 nonresponders. Our analysis shows that HU response was significantly associated with patients having IVSI-1 or CD 30 mutation (P<0.001), age at first transfusion >1 year (P<0.001), and with the presence of XmnI polymorphism (P<0.001). The single-nucleotide polymorphisms of BCL11A were more prevalent among responders, but could not show significant association with HU response (P>0.05). Cumulative effect of all 5 predicting factors through simple binary scoring indicates that the likelihood of HU response increases with the number of primary and secondary genetic modifiers (P<0.001). Predictors scoring is a pragmatic tool to foresee HU response in patients with BTM. The authors recommend a score of ≥2 for starting HU therapy in Pakistani patients with BTM.

Evaluation of the High Resolution Melting Approach for Detection of β-Thalassemia Gene Mutations

β-Thalassemia (β-thal), an autosomal recessive hemoglobinopathy, is one of the most common genetic disorders in Pakistan. Awareness of this disease, genetic counseling, extended family carrier screening and prenatal diagnosis (PND) are helpful in prevention and control. Currently, direct DNA sequencing and multiple amplification refractory mutation system-polymerase chain reaction (MARMS-PCR) are the methods used to detect β-thal mutations, the latter being the most widely used. This study aimed to evaluate PCR-high resolution melting (PCR-HRM) analysis for the detection of most common β-thal mutations that are found in Pakistan. This study was designed to identify the β-thal mutations using PCR-HRM analysis in a total of 90 samples [blood and chorionic villus sampling (CVS)]. These samples were first screened for routine mutations by MARMS-PCR and then evaluated by PCR-HRM analysis. The results of PCR-HRM analyses were further confirmed by direct DNA sequencing and all analyses interpreted the same results in all 90 samples. Eleven cases (36.6%) were detected to carry IVS-I-5 (G>C) (HBB: c0.92 + 5G>C), six cases (20.0%) with frameshift codons (FSC) 41/42 (-TTCT) (HBB: c.126_129delCTTT), five cases (16.0%) were diagnosed with codon 15 (G>A) (HBB: c.47G>A), three cases (10.0%) were found with codon 30 (G>C) (HBB: c.93G>C), one case was diagnosed with FSC 16 (-C) (HBB: c.51delC), one with IVS-I-1 (G>T) (HBB: c0.92 + 1G>T) and one with codon 5 (-CT) (HBB: c.17_18delCT). The PCR-HRM analysis represents a less tedious and more useful method for the detection of β-globin gene mutations.