Epilepsy is a common neurological disorder, and mutations in genes encoding ion channels or neurotransmitter receptors are frequent causes of monogenic forms of epilepsy. Here we show that abnormal expansions of TTTCA and TTTTA repeats in intron 4 of SAMD12 cause benign adult familial myoclonic epilepsy (BAFME). Single-molecule, real-time sequencing of BAC clones and nanopore sequencing of genomic DNA identified two repeat configurations in SAMD12. Intriguingly, in two families with a clinical diagnosis of BAFME in which no repeat expansions in SAMD12 were observed, we identified similar expansions of TTTCA and TTTTA repeats in introns of TNRC6A and RAPGEF2, indicating that expansions of the same repeat motifs are involved in the pathogenesis of BAFME regardless of the genes in which the expanded repeats are located. This discovery that expansions of noncoding repeats lead to neuronal dysfunction responsible for myoclonic tremor and epilepsy extends the understanding of diseases with such repeat expansion.

Several lines of evidence have suggested altered functions of the brain-derived neurotrophic factor (BDNF) in the pathogenesis of neurodegenerative diseases including Alzheimer's disease (AD).In the search for polymorphisms in the 5Ј-flanking and 5Ј-noncoding regions of the BDNF gene, we found a novel nucleotide substitution (C270T) in the noncoding region. We performed an association study between this polymorphism and AD in a Japanese sample of 170 patients with sporadic AD (51 early-onset and 119 late-onset) and 498 controls. The frequency of individuals who carried the mutated type (T270) was significantly more common in patients with late-onset AD than in controls (P = 0.00004, odds ratio: 3.8, 95% CI 1.9-7.4). However, there was no significant difference in the genotype distribution between the patients with early-onset AD and the controls, although this might be due to the small sample size of the early-onset group. Our results suggest that the C270T polymorphism of the BDNF gene or other unknown polymorphisms, which are in linkage disequilibrium, give susceptibility to late-onset AD. We obtained no evidence for the possible interactions between the BDNF and apolipoprotein E (APOE) genes, suggesting that the possible effect of the BDNF gene on the development of late-onset AD might be independent of the APOE genotype. Molecular Psychiatry (2001) 6, 83-86.Alzheimer's disease (AD) is a neurodegenerative disease characterized by loss and atrophy of basal forebrain cholinergic neurons and the limbic structures.

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Gastrointestinal dysfunction, especially constipation, is one of the major problems in the daily life of patients with Parkinson's disease (PD). About 60 to 80% of PD patients suffer from constipation. Several studies have proven that constipation appears about 10 to 20 years prior to motor symptoms. More recently, Abbott et al. have found from a large scale prospective study that lower frequency bowel movements predict the future risk of PD. Furthermore, Braak et al. have found that Lewy neuritis and Lewy bodies, the hallmarks of PD pathology, appear in the dorsal nucleus of vagus in the earliest stage of the disease and then extend upward through the brain stem to reach the substantia nigra in the third stage. They also hypothesize that some yet undefined toxins break through the mucosal barrier of the intestine and are incorporated into the axon terminal of the vagus nerve and transported in a retrograde manner to the vagus nucleus. In this study, we assessed bowel movements and nutritional status in Japanese patients with PD. We found that intake of water was significantly decreased in PD patients from early life and associated with their constipation. Ninety four patients with PD (M 50, F 44) were enrolled. Nutritional status was assessed using the Self-administered Diet History Questionnaire (DHQ). Total water intake was calculated from the consumption of coffee, green tea, and tea. We also questioned the behavior of water drinking from the early stage of life. The questionnaire for bowel movements concerned the frequency of defecation, age of onset of constipation, and age of onset of motor dysfunction. Less than one bowel movement in 3 days was defined as constipation. The nutritional status of PD patients did not differ significantly from those of controls though several studies have shown excess intake of animal fats or reduced consumption of coffee are risks in PD. In contrast, water intake was significantly lower in PD patients than controls (604.0+/-377.2 ml/d vs 909.5+/-531.6 ml/d; P<0.0001). Interestingly, PD patients tended not to feel thirsty and thus they had no desire to drink water throughout their life. Seventy four patients out of 94 (78.7 %) complained of constipation. Mean bowel frequency was once per 3.3+/-1.1 days and 71.1% of patients were defined as having constipation. Women suffered from constipation more frequently than men (82.4% vs 61.9 %). In 33 patients out of 74 (44.6 %), onset of constipation preceded motor disturbance by an average time of 18.1+/-18.8 years. Furthermore, the amount of water intake correlated inversely with the severity of constipation and the depletion of water intake preceded constipation in most cases. The present results support previous findings that constipation precedes the onset of motor dysfunction in PD. To our knowledge, this is the first report to point out latent water depletion in PD patients. It is not certain at present whether coffee or caffeine themselves are the protective factor for PD or alternatively the amount of water in coffee drinking...

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