Successful pregnancy outcome in a woman with argininosuccinate lyase deficiency

Abstract

Argininosuccinic aciduria (ASAD) is caused by deficiency of the fourth enzyme of the urea cycle, argininosuccinic acid lyase (EC 4.3.2.1; McKusick 207900). It results in the accumulation of large amounts of argininosuccinic acid in tissues and all the body fluids (Brusilow and Horwich 1995). The disorder may vary in severity from neonatal hyperammonaemia, which if untreated is fatal, to a biochemical abnormality without apparent clinical sequelae (Brusilow and Horwich 1995). A number of patients survive to adulthood and an increasing number have normal or near normal intelligence (Brusilow and Horwich 1995). There are, however, few reports of pregnancy outcome in women affected with this condition. Those available suggest that the offspring may not be at risk for development delay (Ward et al 1990; Worthington et al 1996). We report here the birth of two children to a woman affected with this disorder. Both were entirely normal developmentally as judged by formal testing. It supports the notion that this condition may not be embryotoxic due either to the inherent nontoxic nature of argininosuccinate or to its failure to cross the placenta in adequate amounts.