Renal disease in Arima syndrome is nephronophthisis as in other Joubert-related Cerebello-oculo-renal syndromes.

Clinicopathological features of the renal disease in Arima syndrome were studied in five autopsy cases. All cases showed insidious development of end-stage renal disease during childhood, preceded by polyuria/polydipsia, anemia, and growth failure. Decreased urinary concentrating ability and excessive sodium loss were the characteristic laboratory findings. Gross examination showed that both kidneys were small and showed multiple cysts of various sizes. The histological examinations revealed chronic sclerosing tubulo-interstitial nephropathy with cystic tubuli predominantly located at cortico-medullary areas. These observations suggest that the renal disease in Arima syndrome is in accordance with nephronophthisis both clinically and pathologically. Contrary to the previous literature which described that Arima syndrome can be distinguished from other Joubert-related cerebello-oculo-renal syndromes by its unique renal disease, i.e., cystic dysplastic kidney (CDK), our study indicates that the phenotype of the renal disease is common among these syndromes as well as abnormalities in other organs, suggesting the underlying similar molecular mechanisms.