Researchers in this study developed a marker for the canine fibrillin 1 gene, which was added to the canine genome linkage map. The canine fibrillin gene is a candidate gene for canine lens luxation, as its human counterpart is thought to cause lens luxation in people. The displacement (or luxation) of lenses in the eyes of Miniature Bull Terriers (MBT) appears to be an inherited disease. The overall objective of this project was to devise a DNA marker that can distinguish normal, carrier and affected dogs and thus enable breeders to avoid producing affected dogs. Researchers collected DNA samples from 78 MBTs that were members of families where lens luxation had appeared. (Eight of these dogs were affected.) They sequenced the canine version of the fibrillin gene and compared the sequences with the fibrillin gene of affected Miniature Bull Terriers. The sequences were identical. Additional research is needed to determine whether a fibrillin-gene mutation is the cause of lens luxation in MBTs.