Abstract
A case of ring chromosome 6 was presented as the first case in Japan. Clinical and cytogenetic studies were carried out on a l-year-six-month-old boy with epileptic seizures, psychomotor retardation, polydactylia, small head, epicanthus and hypertelorism.
The parents were non consanguineous. The delivery was normal and his birth weight was 2, 370g. His initial motor development was almost normal until about 10 months after birth. At 8 months after birth he developed nuchal atonic seizures (neck flexon toward right foreward) with eye ball elevation. These attacks were seen five to six times per hour only on waking and did not occur in series.
Physical status on admission revealed a small boy with slightly apathetic facial appearance. DQ was 50 (Tsumori-Inage method). Routine laboratory examination revealed no abnormalities. The C-banding technique showed a ring 6 chromosome, with the break points located on bands p25 and q27. By C-band staining 80 per cent of cells showed the monocentric ring and 20 per cent of cells showed the dicentric ring.
Only nine cases of ring chromosome 6 (including propositus) have been reported in the world. Specific clinical manifestations are not yet known in this disease. Polydactylia and intractable seizures with hypsarhythmia have not been recorded in the previous cases. The seizures were not typical of infantile spasms, and could not be controlled completely although the frequency of attacks was reduced by PB, DPA, BZP and Vitamin B6.
