Hb H disease in a Turkish family resulting from the interaction of a deletional ?-thalassaemia-1 and a newly discovered poly A mutation

PubMedID: 1581238Summary We have analysed the ?-globin gene defects present in several members of a large family from Southern Turkey. One deletional ?-thalassaemia-1 (type MED-II) was found in 10 subjects; this deletion is in excess of 26.5 kb and includes all and ?-globin genes. Besides the common types of deletional ?-thalassaemia-2 (—3.7 kb and —4.2 kb) we observed a nondeletional ?-thalassaemia-2 that results from an AG mutation (AATAAAÁTGAA) in the polyadenylation signal of the ?2-globin gene; the same AG replacement is present in the ??l gene. The mutation must cause a considerable ?-chain deficiency as is evidenced by the haematological data for five members with Hb H disease due to a compound heterozygosity for ?-thalassaemia-1 (MED-II) and the newly discovered poly A mutation. Several members had additional ß-chain abnormalities (Hb S, Hb D-Los Angeles, ß-thalassaemia); the 11 persons with a Hb S heterozygosity and various ?-globin gene defects (—?/??; ?T?/??, ——/??, —?/—? and ——/?T?) showed a decrease in the level of Hb S that was directly related to the severity of the ?-chain deficiency. Copyright © 1992, Wiley Blackwell. All rights reserve