[A case of spinocerebellar ataxia type 3 (SCA3) associated with isolated ACTH deficiency]

41-year-old woman who was admitted to our hospital because of an acute onset of unconsciousness on October 22, 1999. The level of blood sugar (BS) was 20 mg/dl. A pituitary hormone secretion test detected an isolated deficiency of ACTH. Neurological examinations showed gaze-evoked horizontal nystagmus in the lateral gaze of both eyes, ataxic speech, a slightly wide-based gait and a slight lack of coordination in the four extremities. A cranial MRI revealed moderate atrophy of the pons and the anterior lobe of the cerebellum. The analysis of SCD gene using white blood cells from the patient found that CAG repeat was abnormally prolonged to 74 CAG repeats in the Machado-Joseph disease 1 (MJD1) gene. We compared our patient with 11 reported cases of cerebellar ataxia associated with pituitary gland hormone deficiencies. Compared with 7 patients of the 11, who were reported as having spinocerebellar ataxia or cerebellar ataxia, none of the 7 received gene analysis of SCD and their deficient hormones differed from ours. Three out of the 7 had chorioretinopathy or chorioretinal atrophy, but the retinas of our patient were normal. One of the remaining 4 patients was diagnosed as having ACTH deficiency as was ours, but the diagnosis of the patient was myoclonus epilepsy associated with ragged red fibers (MERRF). The last 3 patients, who were diagnosed as having Boucher-Neuhäuser syndrome, were similar to ours in terms of cerebellar ataxia but they were different in the presence of different hormone deficiencies and chorionretinopathy. Such an association of SCA3 and isolated ACTH deficiency as found in our patient has not been reported previously. The pathogenic mechanism of this association remains to be solved.