Genetic etiologies of at least 20% of autosomal dominant cerebellar ataxias (ADCAs) have yet to be clarified. We identified a novel spinocerebellar ataxia (SCA) form in four Japanese pedigrees which is caused by an abnormal CAG expansion in the TATA-binding protein (TBP) gene, a general transcription initiation factor. Consequently, it has been added to the group of polyglutamine diseases. This abnormal expansion of glutamine tracts in TBP bears 47--55 repeats, whereas the normal repeat number ranges from 29 to 42. Immunocytochemical examination of a postmortem brain which carried 48 CAG repeats detected neuronal intranuclear inclusion bodies that stained with anti-ubiquitin antibody, anti-TBP antibody and with the 1C2 antibody that recognizes specifically expanded pathological polyglutamine tracts. We therefore propose that this new disease be called SCA17 (TBP disease).

We report a novel mutation of tau (L266V missense mutation in exon 9) which may cause a type of familial frontotemporal dementia. The brain of a patient showed Pick body-like inclusions and unique tau-positive, argyrophilic astrocytes with stout filaments and naked, round, or irregular argyrophilic inclusions with deposits of both three-repeat and four-repeat tau. Recombinant tau with a L266V mutation showed a reduced ability to promote microtubule assembly, which may be the primary effect of the mutation.

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Coiled bodies and interfascicular threads are conspicuous white matter abnormalities of brains of patients with progressive supranuclear palsy (PSP). Both structures are argyrophilic and immunoreactive for the microtubule-binding protein tau. This report concerns the ultrastructural localization of interfascicular threads and their relationship to coiled bodies in five PSP patients. We showed for the first time that abnormal tubules with a 13- to 15-nm diameter and fuzzy outer contours were the common structures of coiled bodies in the oligodendroglial perikarya and of interfascicular threads. Moreover, the tubules were immunolabeled by anti-tau antibodies. The abnormal tau-positive tubules of interfascicular threads were located in the inner loop of the myelin sheath. Our study further indicated that the thread-like structures in the white matter comprised, at least in part, oligodendroglial processes, and that they were also present in gray matter. We consider that the formation of coiled bodies in the perikarya and of interfascicular threads represents a common cytoskeletal abnormality of the oligodendroglia of PSP patients. Moreover, even though the white matter alterations of PSP resemble those of corticobasal degeneration, there are certain ultrastructural differences in the abnormal oligodendroglial tubules of the two diseases.

SUMMARY A male with mitochondrial myopathy, encephalopathy, lactic acidemia, and strokelike episodes is reported. He had also recurrent episodes of ileus. Muscle biopsy revealed ragged-red fibres. The cytochemistry of cytochrome c oxidase (CCO) showed scattered nonstained fibres, while all muscle fibres were heavily stained by immunocytochemistry using CCO antibody. These findings suggest that partical CCO deficiency may be present in the skeletal muscles of the patient. NADH cytochrome c reductase in the patient's muscle mitochondria was low compared with normal controls (about 26%), although succinate cytochrome c reductase was normal. Coenzyme Q1O administration (90mg/day) did not improve CSF lactate levels, but did decrease plasma lactate levels. His muscle weakness slightly improved.Mitochondrial myopathy denotes a group of various disorders with mitochondrial abnormalities. In 1977, Shapira et al' noted a group of diseases characterised by central nervous system (CNS) symptoms, and advocated the term mitochondrial encephalomnyopathy, suggesting the presence of a common metabolic disorder in the muscle and CNS. Among patients with this disorder, Pavlakis et al2 described two of their own and nine in the literature showing mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS), and considered this condition to be a distinct clinical entity. We examined enzyme activity in the mitochondrial electron transport system in a patient with MELAS, and studied the effects of the administration of coenzyme Q0 (CoQO0), an important component of the system. Clinical features as well as the results of th-istreatment are reported.