A search for anomalies in the zeta, alpha, beta, and gamma globin gene arrangements in normal black, Italian, Turkish, and Spanish newborns.

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 approximately 2.5 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 arrangement 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----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.