P04.12: Current status of prenatal diagnosis of beta‐thalassemia in Egyptian patients: a preliminary report

Abstract

Objectives: Beta-thalassemia is the commonest genetic disorder in Egypt with an estimated carrier rate of 9–10%. The aim of the study was to look at the common mutations found in our population and the impact of prenatal diagnosis on parents attitudes. Methods: Prospective analysis of cases referred for prenatal diagnosis of thalassemia at Fetal Medicine Unit, Cairo University from 2007 till 2010. Families with previous affected child had molecular assessment of their mutations as well as in the affected siblings. In future pregnancies they would be referred for invasive testing at 11–12 weeks where chorionic villous samples (CVS) were obtained or amniocentesis samples were taken for those who show at later gestations. All cases would first undergo a detailed first trimester scan including assessment of risk for chromosome abnormalities using Medison Accuvix XQ machine (Korea). Samples were analyzed for point mutations using PCR reversed hybridization techniques, in cases with absence of mutant primers direct automated DNA sequencing is performed to located the uncharacterized DNA mutation. Patients with anomalies or high risk for chromosome abnormalities are counselled for fetal karyotype accordingly. Results: Forty one cases were sampled of which 28 cases were CVS and 13 were amniocentesis. Commonest mutations seen were IVS 110, IVS 1-6, IVS 1-1. Other mutations found were IVS 2-1, IVS 2848, IVS 2-745, Codon 5, 30, 39, 27, 87, some were uncharacterized. 13 cases were affected, 5 were normal and 23 cases were carriers. Nearly half of the affected cases were homozygous and other half were compound heterozygous. No miscarriages due to procedures occurred and 1 CVS case was repeated due to inadequate sample. Conclusions: Premarital counselling and couple screening is available but under-utilized. The availability of prenatal diagnosis service changed the current attitude of couples. The hope for bone marrow transplantation seems promising from normal siblings in carrier families.