Kotaro Endo

Unstable expansion of CAG repeat in hereditary dentatorubral–pallidoluysian atrophy (DRPLA)

Hereditary dentatorubral–pallidoluysian atrophy (DRPLA) is an autosomal dominant neurologic disorder characterized by variable combinations of myoclonus, epilepsy, cerebellar ataxia, choreoathetosis and dementia. By specifically searching published brain cDNA sequences for the presence of CAG repeats we identified unstable expansion of a CAG in a gene on chromosome 12 in all the 22 DRPLA patients examined. A good correlation between the size of the CAG repeat expansion and the ages of disease onset is found in this group. Patients with earlier onset tended to have a phenotype of progressive myoclonus epilepsy and larger expansions. We propose that the wide variety of clinical manifestations of DRPLA can now be explained by the variable unstable expansion of the CAG repeat.

GTP cyclohydrolase I gene in hereditary progressive dystonia with marked diurnal fluctuation.

We previously reported four different mutations in the coding region of GTP cyclohydrolase I (GCH-I) gene in patients with hereditary progressive dystonia with marked diurnal fluctuation (HPD). We found two independent new mutations (leucine 79 proline and a deletion in exon 4) in patients with HPD. We also found four families of HPD without any mutations in the coding region of GCH-I gene.

Machado-Joseph disease in four Chinese pedigrees Molecular analysis of 15 patients including two juvenile cases and clinical correlations

Article abstract-Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disorder associated with the expansion of a (CAG)n array in the MJD1 gene. We analyzed the sizes of the (CAG)n array using DNA samples from 61 members of four Chinese MJD families and 18 Chinese normal control subjects and confirmed that the (CAG)n array in 15 MJD chromosomes was expanded to 72-86 repeat units. There were no subjects with (CAG)n array sizes intermediate between those of normal and MJD affected groups. Meanwhile, we found a significant negative correlation between the age of onset of symptoms and (CAG)n array size. The largest (CAG)n array of 86 repeat units was in the youngest patient, whose age of onset was 5 years. The intergenerational increase in number of CAG repeat units was associated with the clinical phenomenon of anticipation. NEUROLOGY 1997;48: 482-485

Strong linkage disequilibrium and haplotype analysis in Japanese pedigrees with Machado-Joseph disease

To identify the markers tightly linked to Machado-Joseph disease (MJD) and to investigate whether a limited number of ancestral chromosomes are shared by Japanese MJD pedigrees, a detailed linkage analysis employing D14S55, D14S48, D14S67, D14S291, D14S280, AFM343vf1, D14S81, D14S265, D14S62, and D14S65 was performed. The results of multipoint linkage analysis as well as detection of critical recombination events indicate that the gene for MJD is localized in a 4-cM region between D14S280-D14S81. We found strong linkage disequilibria at AFM343vf1 and D14S81, and association of a few common haplotypes with MJD. These results indicate that there is an obvious founder effect in Japanese MJD and suggest the possibility of the existence of predisposing haplotypes which are prone to expansions of CAG repeats.

A possible variant of neuro-Behçet disease presenting chronic progressive ataxia without mucocutaneo-ocular symptoms

Behçet disease (BD) is a chronic relapsing multisystem disorder of unknown etiology, which preferentially affects the oral and genital mucous membranes, skin, and eyes. Neurological involvement is one of the most serious manifestations of BD, known as neuro-Behçet disease (NBD). We here describe clinical, radiological, and neuropathological findings for two patients with a possible variant of NBD, who manifested progressive ataxia in the absence of mucocutaneo-ocular signs characteristic for BD. Both patients presented a slowly progressive cerebellar phenotype, accompanied by behavioral changes and sphincter disturbance. Brain MRI scan revealed mild atrophy in pons and cerebellum. Both patients showed a mild CSF pleocytosis, and were positive for HLA-B51. The post-mortem examination performed in one patient, showed widespread foci of chronic encephalitis, consistent with the diagnosis of NBD. Steroid pulse therapy was effective in one patient. Identifying the progressive ataxia phenotype of NBD without mucocutaneo-ocular symptoms is important, because these patients may benefit from early steroid therapy.

Isolated bilateral masseter atrophy in X-linked recessive bulbospinal neuronopathy

Now that it is possible to distinguish X-linked recessive bulbospinal neuronopathy (SBMA) from similar diseases using genetic analysis of the androgen receptor (AR) gene, there are case reports of unusual clinical features of SBMA. [1,2] We report a very atypical patient who had isolated bilateral masseter weakness and relatively short elongation of the CAG repeats in the AR gene. A 50-year-old Japanese man, whose family history included brothers with hand tremor, gradually …