Localization of the genetic defect in a canine cerebellar ataxia

Abstract

Primary granule cell degeneration (PGD) is an autosomal recessive cerebellar ataxia that has been described in Jack Russell Terriers. This ataxia differs from existing mouse models and most other ataxias in that it has a very early onset and it exhibits primary granule cell loss rather than Purkinje involvement. Homozygosity mapping was used to analyze the canine genome of a small panel of affected animals. This screen included 496 markers, of which 377 were ruled unlikely to be linked to the defective locus. An unexpected level of homozygous and otherwise uninformative markers was seen in this screen, attributable to the close relationship between the animals studied. We were able to rule out 24 of the 38 autosomal chromosomes, leaving 16 possible regions containing the defective locus. Within these regions are 12 relevant genes suggested for further study.