Case 1. III.2 (Fig.), a 10-year-old Caucasian male, was first seen at the University of Kansas Medical Center in September 1968, complaining of uncontrollable movements. He was the product of a full-term gestation and uneventful delivery with a birthweight of 4593 g. Other than the main complaint, growth and development had been normal. He had the usual childhood diseases without a history suggestive of rheumatic fever. The family history revealed that two sibs (Cases 2 and 3) were likewise affected, but no similar problem was found in the remaining female sibs nor in any other family member. The mother and father were 30 and 33 years old, respectively, and both were physically and intellectually normal. The three surviving grandparents were in their fifties and were neurologically normal. The deceased paternal grandfather died at the age of 51 of a myocardial infarction, though his previous health had been good. No consanguinity was detected. The unusual movements in the patient were first noted by the maternal grandmother at approximately 4 years of age, and were observed to progress for two or three years before stabilizing in their present intensity. No associated tremors, seizures, or dysphagia were present nor was there gross lack of co-ordination or loss of motor strength. Physical examination at the time of admission revealed a w1ll-developed, well-nourished intelligent male who exhibited constant choreo-athetotic movements of the extremities and neck, absent only during sleep. There was no evidence for cerebellar or posterior column dysfunction and all sensory modalities were intact. Muscle mass, tone, and strength were normal and symmetrical, and there was no tremor, rigidity, or spasm. Deep and superficial reflexes were equal and symmetrical, and the plantar responses were flexor bilaterally. All other aspects of the physical examination were within normal limits. The following laboratory investigations were performed and were found to be normal: urinalysis, complete blood count, fasting blood sugar, serum calcium and phosphorus, blood urea nitrogen, hepatic function studies, serum protein electrophoresis, serum aldolase, caeruloplasmin, and uric acid and urinary lead and copper. Urinary amino acid chromatogram, electroencephalogram, routine chest and skull x-rays, and electromyographic and nerve conduction studies were all normal. A karyotype showed the expected 46/XY pattern. Analysis of the spinal fluid showed nothing unusual, and the opening and closing pressures were normal. There was no change in the patient's condition during his hospital stay and he was discharged on procyclidine. Follow-up studies revealed no substantial change five months after discharge.