A far advanced case of gyrate atrophy in a 12‐year‐old girl

Abstract

Gyrate atrophy (GA; McKusick 25887) is a progressive chorioretinal dystrophy with an autosomal recessive mode of inheritance. In this disorder there is a deficiency of the mitochondrial matrix enzyme ornithine-f-aminotransferase (OAT). Ocular symptoms usually present late in the first decade of life. Ophthalmological findings include myopia, constricted visual fields, elevated dark adaptation thresholds (night blindness), very small or absent electroretinographic responses, and characteristic patchy chorioretinal atrophy distributed circumferentially around the peripheral fundus. Gradually the round patches of atrophy coalesce to form widespread chorioretinal atrophy extending to the posterior pole. Cataracts develop requiring surgical intervention, and eventually blindness occurs due to progressive loss of functional retina at the age of 40 to 50 (Valle and Simell, 1989). Plasma ornithine levels range from 400 to 1400/~mol/L, and 0.5 to 10mmol of ornithine is excreted daily. Glutamate, glutamine, lysine, creatine and creatinine concentrations in plasma are modestly reduced. The pathophysiological mechanism responsible for the chorioretinal dystrophy in GA is not known. Hyperornithinaemia or associated secondary metabolic abnormalities may play an important role, but until the pathophysiology is understood, there is no assurance that correction of biochemical abnormalities in plasma will actually be beneficial (Berson et al., 1981). Four general therapeutic approaches have been used: pharmacological doses of pyridoxine, reducing the intake of arginine and administration of creatine or proline. In this paper we described a 12-year-old patient with night blindness and myopia as the first symptoms of gyrate atrophy with ornithinaemia.