ISOLATED SULFITE OXIDASE DEFICIENCY PRESE NTING AS A LEIGH-SYNDROME

Background. - An enzyme deficiency can be demonstrated in 15 to 20% of cases of Leigh syndrome. A case of isolated sulphite oxidase deficien cy is reported in a girl presenting with Leigh syndrome. Case report. - An 8 month-old girl was admitted suffering from hypotonia and slow i ncrease of head circumference (- 1 SD). Examination showed spastic qua driplegia, dyskinesia, axial hypotonia and difficulties in swallowing. The patient had a coarse face, broad nasal bridge, long philtrum and ectopia lentis. Brain CT scan showed bilateral hypodensity of lenticul ar nuclei and moderate cortical atrophy. Amino acid chromatography sho wed accumulation of 5 sulfocysteine and low levels of cysteine. The su lphite test was positive. Sulphite oxidase activity in fibroblasts and liver was undetectable contrasting with a normal activity of xanthine oxidase. Progressive brain damage led to death at 1 year of age Prena tal diagnosis of sulphite oxidase deficiency was made in two further p regnancies. Conclusions. - The search for sulphite oxidase deficiency must be included in discussing the etiology of Leigh syndrome; the sul phite test is a simple method of screening such cases.