Screening of Five Common Beta Thalassemia Mutations in the Pakistani Population: A basis for prenatal diagnosis.

Thalassemia is one of the most common autosomal single-gene disorder worldwide. The highest prevalence of the disease is in the "thalassemia belt" which includes the Mediterranean region, parts of the Middle East, the Indian subcontinent, the southern parts of the Far East, Pakistan and South-East Asia. This study aimed to detect the common molecular abnormalities of the beta thalassemia syndrome in Pakistan.The study was conducted at the Institute of Hematology, Baqai Medical University, Karachi, Pakistan from August 2004 to November 2007. Blood samples of patients with beta thalassemia major (n = 400) were collected from hospital transfusion centres and diagnostic laboratories in different districts of Karachi representing five major ethnic groups including Punjabi, Pathan, Sindhi, Baluchi and Urdu speaking. All the samples were analysed for five common mutations by using the polymerase chain reaction technique ARMS (amplification of refractory mutation system).The data revealed five common mutations including IVS 1-5(G→C), Fr 41/42(-CTTT), Fr 8/9 (+G), IVS 1-1 and Del 619. These accounted for 90% of the total beta thalassemia genes in Pakistan. The IVS 1-5(G→C) was found to be the most common beta thalassemia gene in the Pakistani population with a frequency of 44.4% present in all major ethnic groups.The results of this study will be helpful in the establishment of a large scale prenatal diagnosis programme in Pakistan.