OBJECTIVES: I. Evaluate the efficacy of oral ribose in patients with a complex 5'-nucleotidase syndrome who have not received uridine (UR) and thymidine (TDR).

II. Evaluate the efficacy of UR/oral ribose and UR/TDR. III. Evaluate the efficacy of oral ribose given in combination with UR/TDR.

PROTOCOL OUTLINE: Newly identified patients receive ribose daily for 8 weeks. Patients who improve continue therapy. If improvement then reaches a plateau, uridine (UR) and thymidine (TDR) are added to the regimen.

Patients who receive no benefit after 8 weeks of ribose are treated with UR/TDR. Patients who improve after 8 weeks of this combination continue therapy.

Ribose is added to the treatment regimen for patients on UR/TDR at entry. At maximal improvement, TDR and UR are sequentially tapered.

PROTOCOL ENTRY CRITERIA:

--Disease Characteristics-- Complex syndrome with excessive skin fibroblast 5'-nucleotidase activity characterized by: Recurrent infection Seizure disorder Speech impairment Attention deficit and behavior problems --Prior/Concurrent Therapy-- Concurrent uridine and thymidine therapy allowed --Patient Characteristics-- Other: No pregnant women