Incidence of Crohn's disease and CARD15 mutation in a small township in Sicily.

Background: The incidence of Crohn's disease (CD) has been shown to be lower in Southern than in Northern Europe. Data on the frequency of the NOD2/CARD15 mutations for Mediterranean area are very scant.

Aim: To determine the incidence of CD from 1979 to 2002 in a township in Sicily together with the allele frequency of NOD2/CARD15 mutations in patients, family members and controls, and to determine the allele frequency of these mutations in sporadic CD from other areas of Sicily in comparison with a control population.

Methods: Casteltermini is a small town close to Agrigento (Sicily) with a population of 9,130 inhabitants. All the diagnoses of inflammatory bowel disease (IBD) made from 1979 to 2002 were obtained through the local health authority. NOD2/CARD15 mutations were studied in 23 out of the 29 patients with CD in Casteltermini, in 60 family members and in 64 controls. NOD2/CARD15 was also studied in 80 sporadic cases of CD disease among Sicilians outside Casteltermini and 118 healthy controls.

Results: From 1979 to 2002, 29 patients with CD and 13 patients with ulcerative colitis (UC) were registered. The 6-year mean incidence of CD ranged from 8.0 to 17 new cases for every 100,000 inhabitants, whereas the mean incidence of UC ranged from five new cases to 7.8 for every 100,000 inhabitants. The allele frequencies of NOD2/CARD15 mutations (L1007finsC, G908R, R702W) were 8.7, 4.3 and 8.7%, respectively, in CD cases; 5.0, 4.2 and 3.1% in family members; 1.6, 2.3 and 3.1% in controls. In sporadic Sicilian CD patients outside Casteltermini the allele frequency was 7.5, 8.1, 6.2% whereas in control population it was 3.3, 1.6, 1.6%.

Conclusions: A high incidence of CD compared with UC was observed in this small town in Southern Italy. The frequency of NOD2/CARD15 mutations in CD is similar to other Caucasian population studied so far.