PDP1 deficiency for Clumber and Sussex Spaniels

PDP 1 is a hereditary disease occurs in Clumber and Sussex Spaniels known as Exercise Intolerance Syndrome. Disease is caused by deficiency of pyruvate dehydrogenase phosphatase 1 (PDP1) that participates in activating of pyruvatdehydrogenase complex (PDHc). This enzyme complex is presented in every cell of the body and is involved in the conversion of food into energy. Phosphatase enzyme is fundamental for the cell function and for survival.

PDP1 gene in Clumber and Sussex Spaniels is very similar to human PDP1 in chromosome 8q22.1. PDP1 gene in dogs was found on the 29th chromosome. PDP1 deficiency causal mutation is known as substitution c.754C> T. This mutation leads to premature stop codon (p.Q252X) during phosphatase enzyme synthesis.

PDP1 deficiency in Clumber and Sussex Spaniels clinically appears as an exercise intolerance. Symptoms include cardiac, pulmonary and neurological complications that result in shortened of affected dog's live. Physical load can occur complete collapse of the dog's body. Some studies suggest association of PDP1 deficiency with fetal and newborn mortality. Disease progression can be decelerated by early instituting of ketogenic diet (food rich in fats and low in sugar) (Abramson et al, 2004).

PDP1 is inhered as an autosomal recessive trait. That means the disease affects dogs with P/P (positive / positive) genotype only. The dogs with P/N (positive /negative) genotype are clinically without any symptom. They are genetically considered carriers of the disease (heterozygotes). In offspring of two heterozygous animals following genotype distribution can be expected: 25 % N/N (healthy non-carriers), 25 % P/P (affected), and 50 % N/P (healthy carriers).
Up to 20% of today's Clumber and Sussex Spaniels population are PDP1 deficiency carriers (Cameron et al, 2007).

.

References:

Abramson,C.J., Platt,S.R. and Shelton,G.D. (2004) Pyruvate dehydrogenase deficiency in a Sussex spaniel. Journal of Small Animal Practice 45 162-165

Cameron,J.M., Maj,M.C., Levandovskiy,V., MacKay,N., Shelton,G.D., Robinson,B.H. (2007) Identification of a canine model of pyruvate dehydrogenase phosphatase 1 deficiency. Molecular Genetics and Metabolism 90 15-23