title: Alternate organization of alpha G-Philadelphia globin genes among U.S. black and Italian Caucasian heterozygotes.
abstract: Seven Hb G-Philadelphia (Hb G) heterozygotes from three Caucasian families from Northern Italy and Sardegna were found to have proportions of Hb G averaging 23%. This value is considerably lower than the 34% or 48% found in Blacks from the Southeastern U.S.A. in whom the alpha G gene is in linkage with alpha-thalassemia-2, i.e. the alpha o alpha G/alpha alpha or alpha o alpha G/alpha o alpha genotypes. Gene mapping identified tandem organization of the alpha G gene in cis with a normal alpha A gene, i.e. the alpha alpha G/alpha alpha genotype, among the Hb G heterozygotes from Italy. The data on the Italian heterozygotes are similar to those obtained by Bruzdzinski et al (14) on a Black family. These results indicate alternate organization of the alpha G genes probably across racial or ethnic boundaries. Comparison of the mean cellular globin amount of alpha G/alpha G gene/cell among Hb G heterozygotes with 4, 3, 2 or 1 alpha globin genes (i.e. alpha A + alpha G) revealed considerable reactivation of individual alpha genes in conditions of mild to severe alpha globin deficiencies.
mesh_terms: D000293:Adolescent; D000328:Adult; D044383:Black People; D002648:Child; D005260:Female; D005796:Genes; D005828:Genetics, Population; D006455:Hemoglobins, Abnormal / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D007558:Italy; D008297:Male; D014481:United States; D044465:White People; D001741:Black or African American
chemical_list: D006455:Hemoglobins, Abnormal; C031679:hemoglobin G Philadelphia