Testing of dogs: HN
Hereditary Nephropathy in English Springer Spaniel
The hereditary nephropathy (HN) is a fatal progressive renal disease, which typically causes renal failure in dogs that are 6 months to 2 years of age. The renal failure is caused by the defect of the glomerular basement membranes that results in alteration of their structure and function in the kidneys of the affected dog. The membrane defects are caused by mutation of a gene that is responsible for the formation of collagen chains. The integrity of the whole collagen network is progressively damaged, and this leads to progressive renal disorders that result in total failure of kidney function.
The affected dogs typically develop severe renal disease by the time they are 6-24 months of age. The clinical signs are often not observed until late in the course of the disease, although proteinuria can be diagnosed through a laboratory test a few months before other clinical signs of the disease can be detected. The histological examination of the kidneys shows various degrees of changes in glomeruli structure.
There is no cure for this disease; treatments can be only symptomatic and therefore genetic testing is of great importance as it may prevent spreading of the disease in the population of English Springer Spaniels.
Nephropathy in English Springer Spaniels is caused by mutation c.2806c>T in exon 3 of COL4A4-gene. The disease has an autosomal recessive pattern of inheritance. The symptoms develop only in individuals who inherit the mutated gene from both parents (mutated homozygote P/P). An individual (heterozygote N/P), who inherits the mutated gene only from one parent, is clinically healthy, however can transfer the mutated gene to its offspring. It is therefore important that in a breeding pair a heterozygous dog is mated only to a healthy mutation-free one (N/N).
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Reference:
Nowend, K.L., Starr-Moss, A.N., Lees, G.E., Berridge, B.R., Clubb, F.J., Kashtan, C.E., Nabity, M.B., Murphy, K.E.: Characterization of the genetic basis for autosomal recessive hereditary nephropathy in the English Springer Spaniel. J Vet Intern Med 26:294-301, 2012. Pubmed reference: 22369189.