Incidence and geographic distribution of HLH in Italy.

Background - The incidence of a disorder with autosomal recessive inheritance in one defined area may be estimated if the incidence of inbreeding in that area is known. Since the rate of consanguineous marriages in Italy is highly variable over the country and the years, the accuracy of the estimate of the gene frequency also depends on the accurate attribution of the geographic origin of the patient's family. faticati & Methods; 60 families of which 47 had one, 9 had two and 4 had 3 affected patients (total 77 subjects). Using the data of the National HLH Registry (Aricò et al, 1992) containing patient's date of birth and diagnosis, and upon accurate investigation of the place of origin, and family names of the parents, grandparents, and grand-grandparents (when available), we have assessed the place of origin of the individual families. It has been possible to compare the frequency of consanguineous marriages among the parents of the patients with that of control population in the same region and years. Results - Our results disclose a high concentration of the families of the patients in Southern Italy, especially Campania and Sicily, The incidence of the disease may be estimated between 1.80,000 and 1:180,000 as a function of the geographic area and methods used.' This estimate is quite lower than previously available data. Conclusion - Identification of an uneven geographic distribution of HLH with two regions with a higher incidence may suggest the presence in these areas of a specific form of the disease. For this purpose we have started genetic studies of the families coming from these areas.