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Hb M-Iwate [alpha 87 (F8) His-->Tyr] was identified as the cause of cyanosis in a 21-year-old Japanese female. Amplification and sequencing of the alpha 2- and alpha 1-genes demonstrated the mutation CD87 CAC (His)-->TAC (Tyr) in the alpha 2-gene. Analysis of the in vitro globin biosynthesis in the reticulocytes disclosed a well-balanced beta/alpha synthetic ratio of 1.04 but an unexpectedly low alpha M/total alpha. Although the cause of the lowered alpha M-globin biosynthesis is not yet clear, it might be related to a defect in chain assembly rather than to a modified stability or a reduced amount of the abnormal alpha-globin mRNA.

1. The expected number of patients with Cooley anemia in Naples, as predicted from heterozygote frequencies, is about 300 which is more than that found from hospital statistics. 2. Considering the presence of at least two beta-thalassemic alleles and the coexistence of a significant incidence of the Lepore gene in the population of the area surrounding Naples (the maximum incidence is thought to be in the neighboring province of Caserta), there are at least 6 different genotypes (3 true homozygotes and 3 genetic compounds) that can give rise to clinically important thalassemia syndromes, ranging from thalassemia intermedia to classic Cooley anemia. 3. Since an alpha-thalassemic gene is also present at polymorphic frequency in this population, this gene may coexist by random assortment in subjects who also have a beta-thalassemia syndrome, thus accounting for part of the variability of globin gene expression. 4. It is remarkable that 2 brothers homozygous for Hb Lepore present differences in the non-alpha/alpha ratio. The clinical differences could be explained by the gamma/alpha mRNA ratio close to 1 in one of them.