Multifactorial disorder: molecular and evolutionary insights of uric acid nephrolithiasis

Nephrolithiasis is a common multifactorial disorder affecting about 10% of the Western populations and it is characterized by the presence of small crystals and stones in the urinary tract. Uric acid nephrolithiasis (UAN) accounts for 20% of all stones but its prevalence varies between countries. Nephrolithiasis is likely caused by several factors but a genetic component has clearly been demonstrated. While studying an ancient founder population in Sardinia, we recently identified a susceptibility locus for UAN on chromosome 10. In this region we identified a missense mutation in a specific isoform of a novel gene is strongly associated with UAN. Through a comparative genomic approach, we did not found a mouse homolog even if we were able to identify the corresponding genomic region, while in Old World monkey we found a canonical gene structure with several stop codons preventing protein production. We detected expression in New World monkeys while in humans we observe a functional protein. It seems, therefore, that, to avoid human disease, a fierce selection worked to develop a renal-haematic urate homeostasis system against excessive hyperuricaemia. ZNF365 emerged during primate evolution and assumed its role in parallel with the disappearance of uricase, probably against a disadvantageous excessive hyperuricaemia.