Glutaric aciduria type 1 is caused by inherited deficiency of
glutaryl-CoA dehydrogenase and subsequent accumulation of neurotoxic
metabolites. Clinically, the disease is characterized by striatal damage
and dystonic movement disorder in untreated infants. Despite newborn
screening and pre-symptomatic therapy start, about one-third of patients
still develop neurological symptoms. Furthermore, progressive white
matter changes and chronic kidney disease highlights the need for
improved therapies. To elucidate the potential of substrate reduction
therapy for GA1 we investigated whether aminoadipate-semialdehyde
synthetase, the first enzyme of the lysine oxidation pathway, could
serve as therapeutic target. Therefore, we studied whether Gcdh knockout (KO) mice, a known animal model for GA1, were rescued by additional knockout of Aass. Gcdh/Aass
KO mice were clinically indistinguishable from wild-type mice and
showed a marked reduction of glutaric acid in brain (20.9 µg/mg protein
vs. 59.2 µg/mg protein; p = 0.001), liver (23.5 µg/mg protein vs. 104.8 µg/mg protein; p = 0.001), and urine (11.9 mol/mol creatinine vs. 166.5 mol/mol creatinine; p = 0.001). The effect was less pronounced for 3-hydroxyglutaric acid. Unlike Gcdh KO mice, Gcdh/Aass KO mice did not develop a severe phenotype under high-lysine diet. In conclusion, knockout of Aass partially rescues the severe phenotype of Gcdh KO mice, providing a potential therapeutic target.