Prenatal Diagnosis of β-Thalassemia and Other Hemoglobinopathies in Southwestern Turkey

Abstract

Our aim was to evaluate the prenatal diagnosis of β-thalassemia (β-thal) and other hemoglobinopathies in a region with high frequency. After detection by premarital or antenatal screening, 312 patients underwent 420 prenatal diagnostic procedures for 407 fetuses in a 10-year period. Fetal samples were collected by chorionic villi sampling (CVS) in the first trimester and amniocentesis and cordocentesis in the second trimester. Mutation analyses of β-globin and cytogenetic analyses were performed and the most common mutations detected were: IVS-I-110 (G>A), IVS-II-1 (G>A), IVS-I-6 (T>C) and IVS-II-745 (C>G). Hb S [β6(A3)Glu→Val, GAG>GTG)] was the most common hemoglobin (Hb) variant with a frequency of 6.3%. Among 407 fetuses, 105 (25.8%) were diagnosed as affected, while 201 (49.4%) were carriers and 101 (24.8%) were normal. Cytogenetic analyses revealed nine fetuses (2.3%) with numerical chromosomal abnormalities as regular or mosaicism. Prenatal diagnosis of common hemoglobinopathies is safe and effective. Performing cytogenetic analysis in excess fetal material is an acceptable option.

Presence of the IVS-I-6-Mutated Allele in Beta-Thalassemia Major Patients Correlates with Extramedullary Hematopoiesis Incidence

“…The IVS-I-6 (T→C) mutation is one of the most common causes of β-thalassemia among individuals of Mediterranean and Middle Eastern ancestry [39,40]. Its high incidence has been reported among populations from Portugal [41]; Spain [42,43]; Albania [44]; the region of former Yugoslavia [45,46,47,48]; Greece [49,50,51,52]; Algeria [53]; Egypt [54]; Palestine [55,56]; Lebanon [57]; Syria [58,59]; Cyprus [60]; Turkey [61,62,63,64,65]; Saudi Arabia [66,67]; Iraq [68,69,70,71]; Iran [72,73,74]; and elsewhere. It results from a base substitution close to the 5′ splice junction, between exon I and intron I, and within a conserved consensus sequence, interfering with mRNA splicing and, consequently, reducing its efficiency.…”

Consanguineous marriages

“…In populations with high consanguinity rates and common inherited blood disorders, community programs for premarital screening to detect carriers of hemoglobinopathies such as thalassemia and sickle cell anemia are in progress as for example in Jordan (Hamamy et al 2007a), Saudi Arabia (Memish and Saeedi 2011), Iran (Fallah et al 2009), Iraq (Al-Allawi and Al-Dousky 2010), Bahrain (Al-Arrayed 2005) and Turkey (Mendilcioglu et al 2011). Carrier detection and genetic counseling programs have been very successful in reducing the birth prevalence of inherited disorders in some populations, such as in Iran (Khorasani et al 2008;Samavat and Modell 2004).…”

Prenatal Molecular Diagnosis of β-Thalassemia and Sickle Cell Anemia in the Syrian Population

“…It has been actively pursued in many countries, such as Cyprus (23), China (24), Taiwan (25), Iran (26), Turkey (2,27), USA (28), UK (29) and Australia (30). Prenatal diagnosis had a great success in decreasing the number of live births with b-thal major (b-TM) in these countries.…”

“…According to the World Health Organization (WHO), b-thal is a well-known monogenic disorder prevalent in more than 60 countries and affecting about more than 5.0% of the world's population. Sickle cell anemia is an inherited disorder of hemoglobin (Hb) synthesis that result from the substitution of glutamic acid by valine at the sixth position of the b-globin chain (Hb S or HBB: c.20A4T) (2,3).…”