HB Mizuho or α₂β₂68(E12)Leu→pro in a Caucasian Boy with high levels of HB F; Identification by Sequencing of Amplified DNA

Abstract

Hb Mizuho, an unstable β chain variant with a Leu→Pro substitution at position β68, was observed in a young Caucasian boy from Kentucky. Identification was made by sequence analyses of amplified DNA and by hybridization of amplified DNA with specific probes. The patient had high Hb F levels up to the present age of nearly 5 years; this high Hb F might in part be responsible for his condition which was considerably milder than that seen in the two patients described in earlier reports. The increased γ chain synthesis may be due to special characteristics of the β-globin gene cistron which are comparable to those observed in sickle cell anemia patients with a relatively mild disease.