High Incidence and Allelic Homogeneity of Wilson Disease in 2 Isolated Populations: A Prerequisite for Efficient Disease Prevention Programs

Abstract

OBJECTIVES: Herein we report the results of mutation-based screening for Wilson disease (WD) in 2 isolated populations of Sardinia and the Greek island of Kalymnos. PATIENTS AND METHODS: Mutation analysis was performed in 110 and 9 WD families originating respectively from Sardinia and Kalymons using single-strand conformation polymorphism and sequencing methods. In Sardinia, a limited screening was performed for -441/-427del in 5290 newborns, whereas in Kalymnos 397 newborns underwent mutation screening for H1069Q and R969Q using appropriate methods. RESULTS: In Sardinia, mutation analysis showed the presence of 6 mutations accounting for 85% of chromosomes, 1 of which (-441/-427del) is present in 61.7% of alleles. The screening for -441/-427del in 5290 newborns revealed the presence of 122 heterozygotes, which is equal to an allelic frequency of 1.15%. Assuming the same distribution of WD mutations in the general Sardinian population, we also inferred an allelic frequency of 0.77% for mutations other than -441/-427del, which accounts for an overall frequency of any WD mutation of 1.92%. Assuming Hardy-Weinberg equilibrium, these data could be translated into a WD incidence of 1 in 2707 live births. In Kalymnos, mutation analysis in 9 WD families revealed the presence of only 2 mutations. The screening of 397 newborns revealed the presence of 18 heterozygotes for H1069Q, 9 for R969Q, and 1 compound heterozygote for these mutations, which is equal to an allele frequency of 3.7%. Assuming Hardy-Weinberg equilibrium, the expected carrier rate is 7%. CONCLUSIONS: These data indicate the need for health education for WD prevention in these isolated populations.