1. We evaluated the inheritance of erythrocyte Na+/Li+ countertransport activity in IgA nephropathy by assessing this parameter in 19 patients with biopsy-proven IgA nephropathy and in their 53 relatives (32 parents and 21 siblings). The possible use of erythrocyte Na+/Li+ countertransport activity as a marker of poor prognosis was also evaluated.
2. A significant correlation was found between ‘familial’ and proband Na+/Li+ countertransport activity, but not between that of spouses.
3. Mean blood pressure, although within the normal range, and Na+/Li+ countertransport activity were significantly higher in patients with proteinuria than in those without proteinuria.
4. Parents of proteinuric patients had a higher Na+/Li+ countertransport activity than parents of non-proteinuric patients.
5. In IgA nephropathy the inheritance of erythrocyte Na+/Li+ countertransport activity was preserved. Therefore genetic factors could play a role in the non-immunological progression of IgA nephropathy.
