A GENETIC-LOCUS SUSCEPTIBLE TO THE OVERT PROTEINURIA IN BUF MNA RAT/

The BUF/Mna (BUF) strain is a high-proteinuria line of rats, and virtu ally all rats develop overt proteinuria by the age of 20 weeks. Geneti c analysis revealed that proteinuria susceptibility was determined pri ncipally by two autosomal recessive genes. These findings prompted us to perform genetic mapping of the genes. (BUF/Mna x WKY/NCrj) F-1 x BU F/Mna backcross rats were raised and maintained for 40-60 weeks to det ect proteinuria. DNAs were extracted from ears of these rats and were examined by linkage study with polymerase chain reaction (PCR) with 13 2 microsatellite markers. Fifty-three out of 167 rats developed protei nuria. DNAs of 51 out of these 53 rats showed homozygous BUF/BUF genot ype in the D13Mgh4 and D13N1 markers located on Chromosome (Chr) 13. T he D13Rat1, D13Mgh2, D13Rat13, D13Mgh3, Syt2, Ren, D13Rat25, D13Mit2, D13Mgh5, and D13N2 markers located on the chromosome also showed stati stically significant linkage to the development of proteinuria, wherea s the other 110 markers showed no linkage. Here we report that a prote inuria-susceptible gene, Purl, resides on a region flanked by the loci D13Mgh3 and D13Mgh4 on Chr 13.