Assignment of the canine paired-box 3 (PAX3) gene to chromosome 37q16-->q17 by in situ hybridization

Congenital sensorineural deafness in dogs: a molecular genetic approach toward unravelling the responsible genes

Deafness is often diagnosed in different dog breeds and has been identified as a significant problem for breeders, owners and clinicians. The aetiology can be inherited or acquired, and a distinction must be made between sensorineural and conductive forms of deafness. This paper provides a brief overview of the varieties of findings in different dog breeds and in one breed in particular including prevalence, phenotypic and gender associations, histology, modes of inheritance and the number of contributing genes in congenital sensorineural deafness. We have also described molecular genetic approaches to canine hearing loss and discuss how comparative genomics could help reduce the prevalence of deafness in affected breeds leading to new insights into the molecular mechanisms of auditory function in both dogs and humans.

Characterization and mapping of canine microsatellites isolated from BAC clones harbouring DNA sequences homologous to seven human genes

Human primers specific for the genes LEP, HBB, PAX3, ESR2, TPH1, ABCA4 and ATP2A2 were used to identify clones in a canine BAC library. Subcloning of the positive BACs in plasmids, screening with microsatellite motifs and subsequent sequencing allowed for the identification of eight novel microsatellites. The presence of the gene of interest was confirmed by sequencing the polymerase chain reaction (PCR) products amplified in the positive BACs. Fluorescent in situ hybridization (FISH) using the positive BACs as probes allowed for the chromosomal localization of the insert DNAs in two canid species, dog (Canis familiaris) and red fox (Vulpes vulpes). The use of gene-associated microsatellites may accelerate the identification of candidate genes for phenotypic traits in linkage studies.

Analysis of the 5' region of the canine PAX3 gene and exclusion as a candidate for Dalmatian deafness

The causative mutation in a gene related to hearing loss in Dalmatians has been elusive. Because of its role in melanocyte migration and differentiation as integral component of the inner ear, we hypothesized that the canine PAX3 (paired box homeotic gene 3) gene could be a candidate for Dalmatian deafness. Therefore, we isolated the canine PAX3 gene and searched for causative mutations within the coding region of important regulatory domains of PAX3. However, no mutations were identified when comparing the DNA sequences of healthy and affected dogs. These results were confirmed by a two-point linkage analysis in 203 Dalmatians transmitting deafness. Our data clearly show that the canine PAX3 gene can be excluded as candidate for Dalmatian deafness.