Hereditary diffuse palmoplantar keratodermas in Slovenia: epidemiologic foci in remote rural areas
BACKGROUND: Previous studies carried out in Slovenia revealed a high frequency of cases of hereditary diffuse palmoplantar keratodermas (DPPK). The relatively small total population of about two million in a small territory and an efficient public health service were favorable preconditions for such a study. METHODS: Existing hospital and outpatient department records served as starting points. Patients were invited to come for a follow-up examination, and visiting the patients at their homes enabled us to gather further data. Thus efforts were made to include all patients with hereditary DPPK in Slovenia. RESULTS: Altogether 170 DPPK patients were detected, giving a prevalence of 8.3 per 100,000 inhabitants. The patients originated from remote, mostly mountainous districts, where the local DPPK prevalence highly significantly exceeded the average Slovene prevalence. The segregation ratio showed an autosomal dominant mode of inheritance. The percentage of persons affected was 34.4% (95% confidence interval 29.8–39.4), lower than expected for autosomal dominant inheritance (the difference is highly significant, P < 0.00001; exact binomial test). CONCLUSION: One autosomal dominant gene alone does not fully explain the transmission of the disorder to siblings. Evidence is produced that additional factors are necessary for the transmission of this genetic condition. The degree of consanguinity and the physical pressure on palms and soles seem to play an important part. It is reasonable to expect that molecular-biology studies linked to the epidemiological data could contribute to the solution of the problem.