Color-blindness in Calabria (Southern Italy): A north-south decreasing trend.

The frequency of color-blindness (CB) in 13,072 males from 409 towns in Calabria is 5.42%. Regional variation in CB within the three provinces of Calabria was studied: Cosenza (northern), Catanzaro (central), and Reggio Calabria (southern). There is a decreasing trend of mean frequencies of CB from Cosenza to Reggio Calabria through Catanzaro: 6.23%, 4.65%, and 3.43%, respectively. The mean frequencies do not take into account the two ethnic minorities present in Calabria: Albanians and Grecanicans. The frequency of CB mean Albanians (7.40%) and the indigenous Calabrian population (5.25%) differs significantly. Moreover, the Albanians do not show the protoanomalous phenotype. The small sample size of Grecanicans does not permit an evaluation of mean CB frequency. Thus, from the perspective of CB, the Calabria region may be considered a mixture of "genetic isolates" reflecting its historical, sociocultural, demographic, and genetic features. Am. J. Hum. Biol. 12:17-24, 2000. Copyright 2000 Wiley-Liss, Inc.