DNA sequence analysis of the human Tg737 gene was performed in 36 patients with the autosomal recessive form of polycystic kidney disease (ARPKD). Coding exons and their adjacent splice sites were screened for mutations. Pathogenic exon or splice region mutations were not identified although one exonic and two intronic polymorphic sites were discovered. These results are in agreement with another study that has recently reported linkage to Chromosome (Chr) 6p21-cen in a set of 16 ARPKD families. STS mapping has localized the gene to a YAC contig that includes D13S175 on chromosome 13q12.1. The polymorphisms found in the htG737 gene will permit its future evaluation as a candidate gene for other recessive cystic renal diseases and as a modifier gene in human PKD.