Distribution of β-Thalassemia Mutations in the Northern Provinces of Iran

Abstract

β-Thalassemia (thal) is one of the most common autosomal recessive disorders in Iran. There are more than two million carriers of β-thal and over 15,000 people affected with β-thal major who live in Iran. Prevalent mutations were identified by examining genomic DNAs isolated from 392 blood samples of β-thal carriers from three northern provinces of Iran. Furthermore, 172 pregnant women were analyzed from the 196 couples who requested pregnant diagnosis for β-thal. Allele identification was carried out using routine reverse dot-blot, amplification refractory mutation system (ARMS), and genomic sequencing. The most common mutation, IVS-II-1 (G→A), is followed, in order of frequency, by codon 30 (G→C), frameshift codons (FSC) 8,9 (+G), FSC 22/23/24 (−AAGTTGG), IVS-I-110 (G→A), IVS-I-5 (G→C), IVS-II-745 (C→G), IVS-I-2 (T→C), FSC 8 (−AA), IVS-I,3′-end (−25 bp), IVS-I-1 (G→A), FSC 36/37 (−T), IVS-I-6 (T→C), FSC 5 (−CT), −28 (A→C), codon 37 (G→A), IVS-II-2,3 (+11/−2), −30 (T→A), and −88 (C→A). We have also revealed the existence of five new mutations from northern Iran, one of which (codon 37) is the first reported for Iran. Furthermore, the rate of unknown mutations is significantly reduced in our study (about 6%). These results could help with establishing a center for prenatal diagnosis, prevention, and control of thalassemia in the northern provinces of Iran.

Keywords:

• β-Thalassemia (thal)
• β-Globin mutation
• Reverse dot-blot