A family study of renal dysplasia

A family study was undertaken to investigate genetic involvement in renal dysplasia, which is defined as abnormal metanephric differentiation. Probands were ascertained through the retrospective examination of necropsy records and the reevaluation of available material, which included microscopic examinations of the kidneys, gross descriptions of organs, and gross photographs. We obtained family histories and performed physical examinations and renal ultrasonography on parents and sibs of the 21 probands. In only one family a sibling with renal dysplasia was discovered; both the proband and the previous stillborn sib had renal dysplasia in association with posterior urethral values. Renal dysplasia could have resulted from urinary tract obstruction secondary to the urethral valves, with inheritance of the valves as the primary abnormality. However, we cannot exclude primary inheritance of the renal abnormality, perhaps with multifactorial determination with a threshold. The empiric recurrence risk of 2.1%, calculated from this family study, was statistically not significantly different from zero. We can assume, therefore, that the multicystic and aplastic types of renal dysplasia, which predominated in this study, are sporadic or rarely familial, but certain other types of renal dysplasia, identified in the literature as familial, probably carry a higher recurrence risk.