Tahiti-families: From Genetic to Phenotype Study of Polynesian Families of Gout Patients

Gout is a chronic disease caused by the deposit of monosodium urate (MSU) crystals in body tissues secondary to hyperuricemia. Patients with gout suffer severe attacks of acute joint pain. As the disease progresses, the joint pain becomes chronic and associated with disabling and deformative manifestations called tophus. This disease is strongly associated with several comorbidities such as cardiovascular disease and chronic kidney failure. Gout is a very common disease, which is affecting 0.9% of the adult population in France and nearly 4% of the North-American population. Data from New Zealand show a particularly high prevalence of gout among Polynesians (minority populations in New Zealand and other islands of the South Pacific) that would be explained by genetic susceptibility and frequently interrelated metabolic diseases. Data on the Polynesian population in New Caledonia suggest prevalence figures close to 7% and prevalence in French Polynesia is assumed to be higher. International genomic studies of gout and hyperuricaemia have identified alleles associated with the occurrence of gout.

The aim is to focus on families with several gouty members (numerous in French Polynesia, and geographically clustered) in order to enable the study of individuals with monogenic gout or with a low number of variants (= cases) determining in the occurrence of gout, as well as a non-gouty family member (= controls).

Dual-energy CT scan (DECT) allows identification and quantification of UMS crystal deposits in the tissue. The volume of crystals correlates not only with the inflammatory activity of the disease but also with the comorbidities that complicate it. Dual-energy scanning has shown the presence of UMS crystals in some hyperuricemic individuals, which could help to identify those individuals most at risk of developing the disease as they already have the stigma of sub-clinical inflammatory activity.