BETA-THALASSEMIA IN THE IMMIGRANT AND NON-IMMIGRANT GERMAN POPULATIONS

In Germany homozygous p-thalassaemia mainly occurs in the immigrant po pulation from endemic regions. In non-immigrants P-thalassaemia is rar e. Heterozygous beta-thalassaemia minor, however, is more common and m ust be considered in the differential diagnosis of hypochromic anaemia . The clinical and molecular data of 221 homozygous patients and 256 n on-immigrant German heterozygous individuals are presented. Clinically , 87% (n = 192) of the homozygotes are classified as thalassaemia majo r (TM) and the other 13% as thalassaemia intermedia (TI). There is a w ide spectrum of 39 thalassaemia mutations which occur with relatively low frequencies in individual cases. In 17/29 TI patients 'mild' mutat ions have been found and in 16/29 there are mutations that are associa ted with increased gamma-globin gene activity. alpha-Thalassaemia is r are and found only in 3/29. In the 256 Germans with heterozygous beta- thalassaemia there are 27 different thalassaemia mutations. The three most common are Mediterranean together accounting for 61%. Also relati vely common (5%) is an otherwise rare frameshift mutation of codon 83 (FS83 Delta G). The other mutations occur in <10 individuals. Two muta tions described here are novel. One of them affects position -2 of the intron 1 splice acceptor site (IVSI-129 A-G) and the other is a delet ion of a single G in codon 15/16 (FS 15/16 Delta G). These data sugges t that beta-thalassaemia in Germans was introduced from the Mediterran ean in about two-thirds of cases and that the remaining third has prob ably originated locally.