Detection of beta-globin gene mutations among Kelantan Malay thalassaemia patients by polymerase chain reaction restriction fragment length polymorphism.

INTRODUCTION: Beta-thalassaemia major is an autosomal recessive disorder that results in severe microcytic, hypochromic, haemolytic anaemia among affected patients. Beta-thalassaemia has emerged as one of the most common public health problems in Malaysia, particularly among Malaysian Chinese and Malays. This study aimed to observe the spectrum of mutations found in Kelantan Malay beta-thalassaemia major patients who attended the Paediatrics Daycare Unit, Hospital Universiti Sains Malaysia, Kelantan, Malaysia, the data of which was being used in establishing the prenatal diagnosis in this Human Genome Centre. METHODS: This was a cross-sectional study conducted with 35 Kelantan Malay beta-thalassaemia major patients. DNA was extracted from the blood collected from the patients and subjected to polymerase chain reaction (PCR) amplification. Six restriction enzymes were used to digest the PCR products for the detection of mutations. RESULTS: Five out of the six beta-globin gene defects were detected, namely, IVS-1 nt5 (G>C), IVS-1 nt1 (G>T), codon 26 (G>A), codon 41-42 (4 bp del) and codon 19 (A>G). The mutation which was not observed in this study was in codon 15 (G>A). The two most common mutations observed were codon 26 (G>A) and IVS-1 nt5 (G>C), which was detected in 26 and 17 patients, respectively. Two patients did not show any of the six mutations. CONCLUSION: Our results added to the existing data on the common beta-globin gene defects in Kelantan Malay beta-thalassaemia patients.

The hemoglobin O mutation in Indonesia: distribution and phenotypic expression.

We have investigated hemoglobin O Indonesia (HbOIna) in related ethnic populations of the Indonesian archipelago: 1725 individuals of the five ethnic populations of South Sulawesi (Bugis, Toraja, Makassar, Mandar, and Kajang) and 959 individuals of the neighboring islands, who were divided into five phylogenetic groups: (a) Batak; (b) Malay from Padang, Pakanbaru, and Palembang in the island of Sumatra; (c) Javanese-related populations (Java, Tengger, and Bali) from the islands of Java and Bali; (d) populations of the Lesser Sunda Islands of Lombok, Sumba, and Sumbawa; and (e) the Papuan-languagespeaking population of Alor Island. Nineteen individuals heterozygous for HbO(Ina) were identified from the Bugis, Toraja, Makassar, and Kajang ethnic populations, but none from the other populations. In all cases, the underlying mutation was found to be in codon 116 (GAG to AAG) of the alpha1-globin gene, resulting in the Glull6Lys amino acid change. The level of HbO in the 17 individuals plus 12 additional family members carrying the mutation was found to be 11.6 +/- 1.0%, significantly lower than the expected 17%-22%, indicating the instability of HbO.

Phenotypic variability of Filipino beta(o)-thalassemia/HbE patients in Indonesia.

Three Indonesian patients with identical genotypes, each compound heterozygotes for Filipino beta(o)-thalassemia/HbE, expressed different clinical severities. One patient has mild disease and is transfusion independent, while the other two are severely affected and transfusion dependent. The size of the Filipino beta(o)-globin gene deletion was confirmed to be 45 kb, resolving conflicting values given in the literature. Neither ameliorating genetic factors such as alpha-globin gene deletions or the XmnI restriction site polymorphism at position -158 upstream of the (G)gamma-globin gene, nor differences in beta-globin gene haplotype, explain the phenotypic variation. These observations have implications for the development of antenatal diagnosis in Indonesia, as at present it is not possible to give an accurate prediction of severity of phenotype for this common genotype.

Molecular Basis of beta-Thalassemia in Indonesia: Application to Prenatal Diagnosis.

Background: To facilitate an effective prevention program, the beta-thalassemia mutations in the different ethnic groups in Indonesia were characterized. Methods and Results: The amplification refractory mutation system and artificially created restriction site were used to detect seven known mutations previously described in the Indonesian population. Other mutant alleles were identified by chemical cleavage mismatch, double-stranded sequencing, and Southern blotting. With these methods 78% of beta-thalassemia mutant alleles have been detected so far. Thirteen different beta-thalassemia mutations were characterized, nine of which had previously been described in the Jakarta population. The most frequent mutation is HbE (29%), followed by IVS1-nt5 (19%), and Cd 35 (8%). The frequencies of the other mutations varied from 4% to less than 1%. Two large gene deletions, Filipino beta-deletion and Hb Lepore, were identified in patients from the eastern part of Indonesia. Conclusions: The ethnicity and clinical hematology of cases in the region should be considered in the screening strategy for carriers and antenatal diagnosis of beta-thalassemia in Indonesia. Direct sequencing proved to be the appropriate method for detecting the unknown mutations, and Southern blotting had to be used for large deletions.