Efficacy of very-low-dose betamethasone on neurological symptoms in ataxia-telangiectasia

BACKGROUND: Ataxia-telangiectasia (A-T) is a non-curable neurodegenerative disorder, associated with progressive neurological dysfunction, oculocutaneous telangiectasia, immunodeficiency, predisposition to cancer and radiosensitivity. A recent study documented improvement in neurological symptoms after a short-term therapy with betamethasone in patients with A-T. Aim of this study was to evaluate the minimum therapeutically effective dosage of betamethasone on neurological symptoms of A-T. METHODS: Six responsive patients with A-T, received two 20-day cycles of oral betamethasone at 0.01 and 0.03 mg/kg/day (10% and 30% of the previously used full dosage), each followed by a 20-day washout period. Clinical and laboratory evaluations were carried out at T0 and at the end of each cycle. Neurological assessment was performed through the Scale for the Assessment and Rating of Ataxia (SARA). The glucocorticoid-induced leucine zipper (GILZ) and glucocorticoid receptor (GR) RNA expression were evaluated before and during the trial through real-time PCR. RESULTS: SARA scores significantly improved in all patients at the dosage of 0.03 mg/kg/day. In particular, three patients exhibited an improvement in 5/8 variables and two patients of 7 and 8 variables, respectively. Furthermore, the clinical improvement was already evident after the lower dosage. The basal GILZ and GR RNA expression were significantly lower in patients than in controls. GILZ expression increased in all patients after the beginning of the therapy, whereas no correlation between GR and the response was found. CONCLUSION: Our data indicate that betamethasone is effective in A-T at a minimal dosage and that GILZ may be a useful biomarker of the clinical response. This study provides Class IIIA evidence that betamethasone at very low dosage is effective in improving neurological signs of patients affected with ataxia-telangiectasia.