Novel promoter and splice junction defects add to the genetic, clinical or geographic heterogeneity of β-thalassaemia in the Portuguese population
✍ Scribed by Paula Faustino; Leonor Osório-Almeida; José Barbot; Deonilde Espírito-Santo; João Gonçalves; Luísa Romão; M. Carmo Martins; M. Maia Marques; João Lavinha
- Publisher
- Springer
- Year
- 1992
- Tongue
- English
- Weight
- 390 KB
- Volume
- 89
- Category
- Article
- ISSN
- 0340-6717
No coin nor oath required. For personal study only.
✦ Synopsis
In order to delineate the spectrum and the relative abundance of beta-globin gene defects causing thalassaemia in the Portuguese population, a representative sample was analysed including 51 beta-thalassaemia carriers along with 26 patients representing different clinical phenotypes. Seven mutations were identified, four of which [codon 39 (C----T), 39%; intervening sequence (IVS) 1 nucleotide (nt) 1 (G----A), 26%; IVS 1 nt 110 (G----A), 17%; IVS 1 nt 6 (T----C), 15%] account for 97% of 93 beta-thalassaemia chromosomes. Two previously undescribed mutations, namely a C----T substitution at position--90 in the proximal CACCC box, and the deletion of nucleotides 4 and 5 (AG) in IVS2 were identified. The uncommon, though ubiquitous, G----T transversion at codon 121 was found once upon haplotype V. Direct prenatal diagnosis can be offered to 95% of couples at risk of bearing a thalassaemic child.