Karyomegaly of tubular kidney cells in human chronic interstitial nephropathy in Tunisia: respective role of Ochratoxin A and possible genetic predisposition.

Karyomegalic nephropathy associated to bizarre enlargement of nuclei in renal tubular epithelial cells was first described by Mihatch in 1979. We present herein additional cases occurring in three siblings suffering from chronic interstitial nephropathy (CIN) of unknown aetiology where the renal biopsies showed numerous enlarged and hyperchromatic nuclei. CIN of unknown aetiology has been previously characterized and showed striking similarities with Balkan Endemic Nephropathy (BEN). Ochratoxin A (OTA) is a nephrotoxic mycotoxin suspected to be the causal agent of the BEN as well as the Tunisian CIN of unknown aetiology. OTA is incriminated in the onset of these disclosed cases of karyomegalic nephropathy since high OTA concentrations were found in blood (505.83 ng/ml, 102.63 ng/ml and 1023 ng/ml) and in urine (94.40 ng/ml and 10.18 ng/ml) of two of them. Moreover, we have investigated OTA in blood and urine as well as in food samples of the entire household (21 people). Our findings suggest (i) a link between OTA and the outcome of this karyomegalic nephropathy, and (ii) the possible involvement of a genetic factor since the three cases have the same haplotype B27/35.