"LPN1 is a polyneuropathy resulting from a 10 base pair deletion within the gene ARHGEF10; dogs homozygous (D/D) for the LPN1 mutation typically develop clinical signs of disease before they reach 3 years of age. At present, LPN1 D/D dogs represent ~11% of all diagnosed cases of Leonberger polyneuropathy; a further 24% of dogs in our research population with a phenotype consistent with or diagnosis of unexplained polyneuropathy have the LPN1-D/N genotype (compared to 12.5% of healthy control dogs). The average age that clinical signs are first noted in these LPN1-D/N dogs, if they develop at all, is 6 years. Due to other causes of neuropathy in Leonbergers, the exact mode of inheritance of the LPN1 form of neuropathy cannot yet be stated for certain." [From University of MN] We have also identified LPN1 homozygous affected Saint Bernards with a biopsy confirmed polyneuropathy and clinical signs consistent with the disease. The LPN1 test can also be used in the Saint Bernard breed to aid in the diagnosis of polyneuropathy and to identify carriers in the breeding population. "The test for LPN1 does not account for all confirmed or suspected cases of laryngeal paralysis and polyneuropathy in the Saint Bernard breed. Until additional DNA-based test(s) are developed, the only way to confirm a suspected diagnosis of laryngeal paralysis is via laryngoscopy and/or nerve conduction study; polyneuropathy is diagnosed via a nerve and muscle biopsy." [From University of MN]