classical citrullinemias meaning

[Medicine]
A group of diseases related to a deficiency of the enzyme ARGININOSUCCINATE SYNTHASE which causes an elevation of serum levels of CITRULLINE. In neonates,clinical manifestations include lethargy,hypotonia,and SEIZURES. Milder forms also occur. Childhood and adult forms may present with recurrent episodes of intermittent weakness,lethargy,ATAXIA,behavioral changes,and DYSARTHRIA. (From Menkes,Textbook of Child Neurology,5th ed,p49)