SstII polymorphic sites in the promoter region of the human cystatin C gene.

By direct sequencing of polymerase chain reaction (PCR) amplified DNA from different individuals, three points mutations have been found in a 220-bp fragment from the promoter region of the human cystatin C gene. The three mutations are all localized within a short segment of 85bp on the same allele. One of the base substitutions results in the generation of a novel SstII restriction site and another in the loss of the commonly occurring SstII restriction site. A PCR-based assay for analysis of the two SstII sites was designed and used to demonstrate Mendelian inheritance of the polymorphism. This SstII restriction fragment lenght polymorphism offers a new probe-independent marker for chromosome 20 linkage studies.