Hb Southern Italy: coexistence of two missence mutations (the Hb Sun Prairie alpha(2) 130 Ala-->Pro and Hb Caserta alpha(2) 26 Ala-->Thr) in a single HBA2 gene.

This study describes a new molecular condition in the α2- globin gene (HBA2) found in six unrelated families from Southern Italy (Campania and Sicily). This new double mutant form of haemoglobin is called Hb Southern Italy and originated from the coexistence of two known mutations occurring in the same globin gene, HBA2 26 G→A (Hb Caserta) and HBA2 130 G→C (Hb Sun Prairie). Hb Sun Prairie was originally observed in Indian patients in either the homozygous state, with severe hemolytic anemia, and in the heterozygous state with microcytosis, or in asymptomatic cases as an α-thalassemia carrier phenotype. Hb Caserta was observed for the first time in a Casertian family (South Italy) that displayed a slowmigrating haemoglobin upon investigation. We report the clinical phenotype and molecular study of this new double mutant form of haemoglobin in heterozygous and homozygous subjects, as well as in association with α°delectional thalassemia.