. This application is for a five year continuation of a grant, first funded, in 1960. The proposed research is a continuation of ongoing investigations which concern: (1) Structural analyses of abnormal hemoglobins (Hbs) to improve our understanding of the pathology of the hemoglobinopathies. Major emphasis will be placed upon unstable Hbs, Hb variants with abnormal functional properties, Hb variants due to silent mutations, etc. The variants will include all chains (i.e., abnormal alpha, beta, gamma and delta chains), while special attention will be given to gamma chain variants that cause hemolytic anemia in the newborn. Methodology includes isolation of the variant chains by chromatography (including preparative reversed phase high performance liquid chromatography (HPLC), isolation of proteolytic peptides by HPLC, amino acid analyses, sequence analysis. Most recently, we added sequencing of DNA containing the abnormal gene, obtained after cloning of amplification; this, however, will only be done if identification of the amino acid substitution in the variant chain is not possible or very difficult. (2) An evaluation of gamma chain variants and gamma-globin gene rearrangements in newborn babies from various parts of the world. The rearrangements include identical genes on one chromosome (G-gamma G-gamma- or A-gamma A-gamma- instead of G-gamma A-gamma-), multiple gamma-globin genes (gamma-gamma-gamma; gamma-gamma-gamma-gamma; gamma-gamma-gamma-gamma-gamma; and gamma-thalassemia (GA-gamma). The investigators propose to continue our efforts to characterize some of the gamma-globin gene triplications and the gamma-thalassemia, at the gene level. The investigators previous studies have indicated different types, due to different crossover locations. (3) A study of an unusual minor gamma chain that was recently discovered in the Hb F of several patients with HPFH (mainly A-gamma) and several SS patients. This chain (called M-gamma) appears to be a A-gamma chain but with a Leu-Met replacement at gamma 141. Family studies clearly suggest that this M-gamma is not the product of a mutant A-gamma-gene. It may well be that this chain is the product of a, yet unidentified gamma-gene, or is the result of misreading. The investigators will intensify our study of the occurrence of this chain in various conditions, and will attempt to clarify its origin. (4) It is proposed to continue with a small subcontract to the Chinese Academy of Medical Sciences (Beiijing, P.R. China). This collaboration will provide many of the necessary samples to conduct the proposed studies; mainly cord blood samples, with abnormal gamma-gene arrangements and samples with unusual Hb variants.
