Coexisting genetic kidney disease explains many cases of ‘familial’ IgA nephropathy where the proband has biopsy-confirmed mesangial IgA deposits

Many familial cases of IgA nephropathy result from mesangial IgA deposition in the setting of coexisting genetic kidney disease. Sometimes, genetic kidney disease is not detected in the proband but is present in another family member. Individuals from families with IgA nephropathy should be offered genetic testing.