Epidemic renal disease of unknown etiology in the Zuni Indians.

An epidemic of renal disease is occurring among the Zuni Indians in western New Mexico. In 1985, 1.6% of Zunis had clinically recognized renal disease and 1% had renal insufficiency. The incidence of end-stage renal disease (ESRD) in 1984 and 1985 was 14 times the rate for US whites, and three times the rates of other Indians in ESRD network 6. One third of the cases of renal disease and ESRD is due to type 2 diabetes, but the etiology of disease in most of the remainder is unknown. Affected subjects range from early childhood to old age. Early signs are hematuria, mild to moderate proteinuria, normal BP, and low total hemolytic complement, normal or low C3 and C4 levels, in about 40% of the cases. The clinical course varies from benign to rapidly progressive renal failure. Biopsies usually reflect an immune-complex mediated mesangiopathic glomerulonephritis, with IgA, IgG, IgM, and C3 variably present in the mesangium. In some cases, there is a very strong familial pattern suggesting autosomal dominant inheritance or a marked communal exposure effect. This may be a genetic disease educed by the consanguinity in the ethnically homogeneous Zuni population. Mesangiopathic renal disease is common in some Oriental populations, and this phenomenon may reflect the American Indians' Oriental ancestry. This disease may also be due to toxic exposures related to jewelry-making, potting, Zuni water, Zuni salt, or herbal or other products used for medicinal or religious purposes. This epidemic is much morbidity and generating huge costs for ESRD treatment. Further study is needed to better understand its etiology.