Screening of Iranian Thalassemic Families for the Most Common Deletions of the β-Globin Gene Cluster

Abstract

δβ-Thalassemia (thal) is a disorder, characterized by increased levels of fetal hemoglobin (Hb F) in adult life. A considerable number of deletions of variable size and position in the β-globin gene cluster are associated with the clinical manifestation of δβ-thal. In this study we have determined the presence of the eight most common deletions in Iranian patients.

Thirty-two patients from 19 families were referred to the Kariminejad-Najmabadi Pathology and Genetics Center, Tehran, Iran (a private genetics center), within the past 3 years with elevated levels of Hb F and low mean corpuscular volume (MCV). After obtaining their informed consent, DNA was extracted from whole blood by the salting-out method. Detection of eight deletions was performed using polymerase chain reaction (PCR). These deletions included the hereditary persistence of fetal Hb (HPFH) 1 (Black) and 3 (Indian), Spanish (−114 kb), Sicilian (−13,377 bp), Chinese ^Gγ(^Aγδβ)⁰-thal (−100 kb), Asian-Indian inversion-deletion ^Gγ(^Aγδβ)⁰-thal, and the Turkish form of inversion-deletion (δβ)⁰-thal, as well as the Hbs Lepore, which are characterized by unequal crossovers between the δ- and β-globin genes.

We found the Sicilian (−13,377 bp) and Hb Lepore deletions as well as the Asian-Indian ^Gγ(^Aγδβ)⁰-thal in 11 (57.89%), three (15.78%) and five (26.31%) families, respectively. None of the aforementioned deletions were found in one of the patients. This is the first study of the deletions involved in δβ-thal in Iranian patients. Our study highlights the importance of detecting these mutations for prenatal diagnosis carrier detection and genotype/phenotype prediction.

Keywords:

• δβ-Thalassemia (thal)
• Iran
• δβ-Globin deletions
• Hereditary persistence of fetal hemoglobin (HPFH)