Molecular basis of Hb H disease in southwest Iran.

Although α0-thalassemia (thal) defects are not very frequent in the Iranian population, Hb H disease does occur in the country. We have analyzed the α gene cluster of 13 patients showing the presence of Hb H to establish the molecular background of this disease in southwest Iran (Shiraz and Hormozgan provinces). Using gap-polymerase chain reaction (gap-PCR) and direct DNA sequencing we have found the − −MED-I deletion, the polyadenylation signal (poly A) mutations αT-Saudiα and αT-Turkishα, and Hb Constant Spring (Hb CS) in association with the common − α3.7 deletion. This study has revealed that: 1) at least six genotypes are responsible for Hb H disease in the area: − α3.7/− −MED-I; − α3.7/αT-Saudiα; αT-Saudiα/αT-Saudiα; αCSα/− −MED-I; − −MED-I/αT-Turkishα; and the atypical forms of Hb H disease − α3.7/αCSα. 2) The molecular background of Hb H disease in the southwest area of Iran is more similar to the Mediterranean type than to the Southeast Asian. 3) Hb Bart's hydrops fetalis syndrome and mild, inter...