Genes,diet and uric acid nephrolithiasis

Uric acid represent the final product of purine metabolism: one-third of daily uric acid production is excreted by the gastrointestinal tract and two-thirds by the kidney. A high uric acid excretion with urine, a low urine volume due to dehydration and an acidic urinary pH value have been suggested to be the most important risk factor for uric acid nephrolithiasis (UAN). Recently mutation analysis showed that a variant (Ala62Thr) in a specific protein isoform (Talanin) is associated with UAN. We found that this variant is rather common in the Sardinian (32%) and Sicilian populations (23%), that are Mediterranean islands, as well as in the Italian peninsula (27%). On the contrary, in Burkina Faso and in Benin, both sub-Saharan countries, mesoendemic regions for Plasmodium falciparum malaria and other parasite infections, a low incidence of this variant was found (1.1% and 1.2% respectively). In Burkina Faso and in Benin, the low incidence of Ala62Thr variant is associated with low presence of UAN and the major classes of stones reported are calcium oxalate and calcium phosphate. These low frequencies for Ala62Thr predisposing to UAN in Burkina Faso and in Benin may represent the result of a selective mechanism where the arid conditions of territory and the characteristic alimentary habits of this part of Africa may represent an obstacle to the expansion of mutated allele.