Genic Equilibrium of Microcythæmia in some Italian Districts

Abstract

MICROCYTHÆMIA, or thalassæmia minor, is an inherited trait due to an autosomal gene (M), with incomplete dominance, which in the homozygous condition is lethal because all MM die in childhood from a severe anæmia (Cooley's disease or thalassæmia major). Silvestroni et al. ¹ showed that its frequency ranges, in Italy, from 0.47 per cent (Florence) up to 10.4 per cent (average of several villages in the district of Ferrara), with a rather irregular distribution through the Italian peninsula and islands. They pointed out that the high percentage of microcythæmia (Mm) in some populations raises the problem of how such a high percentage of heterozygotes can be preserved through many generations although the gene M is continually eliminated because all homozygotes (MM) die in early childhood.