איבחון וטיפול ביתר פנילאלנינמיה ממאירה על רקע חסר האנזים

תקציר

Treatment of Phenyl-Ketonuria due to Dihydropteridinereductase Deficiency 

B. Sela, J. Blonder, I. Peled, G. Schwartz

Institute for Pathological Chemistry and Child Development, Sheba Medical Center, Tel Hashomer; Clinical Biochemistry Dept., Sackler Faculty of Medicine, Tel Aviv University

Most cases of hyper-phenylalaninemia are due to deficiency of phenyl-alanine hydroxylase that converts phenyl-alanine to tyrosine. This enzymic reaction is facilitated by the co-factor tetrahydrobiopterin (BH₄). A defect in the latter substrate leads to increased phenyl-alanine in 1-2 cases per million live births. Such cases are characterized by a degenerative brain process, and pronounced neurologic symptoms that cannot be prevented by a low phenyl-alanine diet alone.

In 3 male newborns a deficiency of dihydropteridine reductase (DHPR) activity was diagnosed, the last in a sequence of 3 enzymes involved in the formation of BH₄. Successful outcome of treatment as well as the results of failure to diagnose and treat affected newborns are described, with emphasis on the logistic problems involved in mass screening.