CSF HYPOCRETIN CONCENTRATION IN VARIOUS NEUROLOGICAL AND SLEEP DISORDERS

Recent CSF and postmortem brain hypocretin measurements in human narcolepsy suggest that hypocretin deficiency is involved in the pathophysiology of the disease. Thus, it is important to study whether neurological disorders also have abnormal CSF hypocretin levels. We therefore measured hypocretins in the CSF of various neurological disorders and obstructive sleep apnea syndrome (OSAS) to identify altered hypocretin levels. CSF hypocretin levels in patients with OSAS and neurological diseases were almost within the normal range in Japanese populations. While, hypocretin levels in patients with narcolepsy-cataplexy are very low. The measurement of hypocretin levels is a useful diagnostic tool in Japanese patients with narcolepsycataplexy

Mutations in the NHLRC1 gene are the common cause for Lafora disease in the Japanese population

Lafora disease (LD) is a rare autosomal recessive genetic disorder characterized by epilepsy, myoclonus, and progressive neurological deterioration. LD is caused by mutations in the EMP2A gene encoding a protein phosphatase. A second gene for LD, termed NHLRC1 and encoding a putative E3 ubiquitin ligase, was recently identified on chromosome 6p22. The LD is relatively common in southern Europe, the Middle East, and Southeast Asia. A few sporadic cases with typical LD phenotype have been reported from Japan; however, our earlier study failed to find EPM2A mutations in four Japanese families with LD. We recruited four new families from Japan and searched for mutations in EPM2A . All eight families were also screened for NHLRC1 mutations. We found five independent families having novel mutations in NHLRC1. Identified mutations include five missense mutations (p.I153M, p.C160R, p.W219R, p.D245N, and p.R253K) and a deletion mutation (c.897insA; p.S299fs13). We also found a family with a ten base pair deletion (c.822-832del10) in the coding region of EPM2A. In two families, no EPM2A or NHLRC1 mutation was found. Our study, in addition to documenting the genetic and molecular heterogeneity observed for LD, suggests that mutations in the NHLRC1 gene may be a common cause of LD in the Japanese population