A Search for Anomalies in the ζ,α,β, and γ Globin Gene Arrangements in Normal Black, Italian, Turkish, and Spanish Newborns

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Abstract
Globin gene mapping analyses of DNA from numerous Black babies, and from newborns from Sardinia, Sicily, Turkey, and Spain have identified the following: A high incidence of .alpha.-thalassemia-2 heterozygotes among Black babies with less than 1% Hb Bart''s at birth and a high incidence of .alpha.-thalassemia-2 among Sardinians, but not among Sicilian, Turkish, and Spanish babies. A relatively high incidence of .zeta.-thalassemia was present among Black babies only, while triplicated .zeta. was seen in four of the five populations. Two Black babies were each found to have a different .theta.1 deletion; two Sardinian babies had a newly discovered .apprx. 25 kb deletion between .zeta. and .psi..zeta.; four babies had the rare Bgl II polymorphism between .psi..zeta. and .psi..alpha.; and one Black baby lacked the Eco RI site 3'' to .zeta.. Quantitation of the .zeta. chain by reversed phase high performance liquid chromatography showed that two-thirds of the babies with four .alpha. genes (.alpha..alpha./.alpha..alpha.) had levels between 0.1 and 1.0%, while nearly 90% of the babies with -.alpha./.alpha..alpha. had similar levels (averaging 0.2% for .alpha..alpha./.alpha..alpha.; 0.35% for -.alpha./.alpha..alpha.; 0.75% for -.alpha./-.alpha.). Additional data indicated that the occurrence and level of .zeta. are related to the level of .beta., i.e. the gestational age. The presence of a .zeta. triplication did not affect the level of .zeta. in cord blood. The extensive search for .gamma.-globin gene anomalies resulted in the discovery of a chromosome with five .gamma. genes. .gamma.-Thalassemia was rare in all populations, while the -G.gamma.-G.gamma.- gene arrrangement was mainly observed among Black babies; this arrangement is primarily responsible for high G.gamma. levels in cord blood samples. The strong correlation between the presence or absence of a C .fwdarw. T mutation at position -158 (measured in Xmn I digests) and the level of G.gamma. was confirmed for adult blood samples. A search for possible anomalies in the -.delta.-.beta.-region through gene mapping with Eco RV gave negative results except for the discovery of a polymorphic site 5'' to .delta. in one of the 371 Black babies tested.