The allopurinol test in patients with Rett syndrome

The Rett syndrome (RS) is a neurodegenerative disorder of unknown aetiology affecting only girls. Among the heterogeneous biochemical abnormalities that have been described associated with RS, some patients show moderately elevated levels of ammonium (Hagberg et al 1983) and/or increased excretion of orotic acid in basal conditions (Hyman and Batshaw 1986) or after a protein or alanine loading (Clarke et al 1990; Thomas et al 1990; Cameron et al 1991). The objective of this study is to get further information on the possible relationship between RS and urea cycle function using the allopurinol test (Brusilow and Valle 1987)