Potential conflict of interest: Nothing to report.
SCARB2 mutations in progressive myoclonus epilepsy (PME) without renal failure†
Version of Record online: 22 JUN 2009
Copyright © 2009 American Neurological Association
Annals of Neurology
Volume 66, Issue 4, pages 532–536, October 2009
How to Cite
Dibbens, L.M., Michelucci, R., Gambardella, A., Andermann, F., Rubboli, G., Bayly, M.A., Joensuu, T., Vears, D.F., Franceschetti, S., Canafoglia, L., Wallace, R., Bassuk, A.G., Power, D.A., Tassinari, C.A., Andermann, E., Lehesjoki, A.E. and Berkovic, S.F. (2009), SCARB2 mutations in progressive myoclonus epilepsy (PME) without renal failure. Ann Neurol., 66: 532–536. doi: 10.1002/ana.21765
- Issue online: 8 OCT 2009
- Version of Record online: 22 JUN 2009
- Accepted manuscript online: 22 JUN 2009 12:00AM EST
- Manuscript Accepted: 22 MAY 2009
- Manuscript Revised: 30 APR 2009
- Manuscript Received: 17 MAR 2009
- Australian National Health and Medical Research Council (NHMRC)
- Andrew Thyne Reid Trust
- Folkha lsan Research Foundation
- Sigrid Jusélius Foundation
- Academy of Finland (Center of Excellence Programme 2006–2011)
Mutations in SCARB2 were recently described as causing action myoclonus renal failure syndrome (AMRF). We hypothesized that mutations in SCARB2 might account for unsolved cases of progressive myoclonus epilepsy (PME) without renal impairment, especially those resembling Unverricht-Lundborg disease (ULD). Additionally, we searched for mutations in the PRICKLE1 gene, newly recognized as a cause of PME mimicking ULD.
We reviewed cases of PME referred for diagnosis over two decades in which a molecular diagnosis had not been reached. Patients were classified according to age of onset, clinical pattern, and associated neurological signs into “ULD-like” and “not ULD-like.” After exclusion of mutations in cystatin B (CSTB), DNA was examined for sequence variation in SCARB2 and PRICKLE1.
Of 71 cases evaluated, 41 were “ULD-like” and five had SCARB2 mutations. None of 30 “not ULD-like” cases were positive. The five patients with SCARB2 mutations had onset between 14 and 26 years of age, with no evidence of renal failure during 5.5 to 15 years of follow-up; four were followed until death. One living patient had slight proteinuria. A subset of 25 cases were sequenced for PRICKLE1 and no mutations were found.
Mutations in SCARB2 are an important cause of hitherto unsolved cases of PME resembling ULD at onset. SCARB2 should be evaluated even in the absence of renal involvement. Onset is in teenage or young adult life. Molecular diagnosis is important for counseling the patient and family, particularly as the prognosis is worse than classical ULD. Ann Neurol 2009;66:532–536