HEREDITARY PERSISTENCE OF FETAL HEMOGLOBIN OR (DELTA-BETA)DEGREES-THALASSEMIA - 3 TYPES OBSERVED IN SOUTH-CHINESE FAMILIES

  • 1 January 1985
    • journal article
    • research article
    • Vol. 66  (6) , 1430-1435
Abstract
Hematological and hemoglobin composition data, and results from extensive gene mapping, using a battery of restriction enzymes and probes, have been used to distinguish different types of hereditary persistance of fetal hemoglobin (HPFH) (or .delta..beta.-thal) among three Chinese families from the southern part of China. The first (Family Z) is an A.gamma.(.delta..beta.)+-HPFH without a detectable deletion and may be the same as, or similar to, that described by Farquhar et al (Am J Hum Genet 35:611, 1983). The second (Family C) resembles a G.gamma.(A.gamma..delta..beta.)o-thalassemia and is characterized by a large deletion of DNA orginating 3'' to the G.gamma. globin gene and extending beyond sequences recognized by the pRK28 probe. Data from various digests indicate possible differences in the 3'' end of the deletion when compared with data for some other types of G.gamma.(A.gamma..delta..beta.)o-thalassemia, described by Trent et al (Br J Haematol 57:279, 1984). The third (Family Zh) concerns a G.gamma. A.gamma.(.delta..beta.)+HPFH, which is characterized in heterozygotes by a fetal hemoglobin level of 20% to 25% with a G.gamma. value averaging 60% and by the absence of any DNA deletion detectable by extensive gene mapping analyses. The C .fwdarw. G mutation at position 202 5'' to the G.gamma. globin gene [characteristic for the high G.gamma.-(.delta..beta.)+-HPFH (Proc Natl Acad Sci USA) 81:4894, 1984); Blood 64:1292, 1984] was absent, but the Xmn I site at position 158 5'' to the G.gamma. globin gene [characteristic for a modest increase in G.gamma. values and thus an increased G.gamma. to A.gamma. ratio (Blood)] was present. No indication has yet been obtained explaining the elevation in both G.gamma. and A.gamma. chains; haplotyping showed that the chromosome carrying this G.gamma.A.gamma.(.delta..beta.)+ determinant is unusual among the Chinese population.

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