Mapping of autosomal dominant cerebellar ataxia without the pathogenic PPP2R2B mutation to the locus for spinocerebellar ataxia 12.

OBJECTIVES: To map the disease locus and to identify a gene mutation in a Japanese family with autosomal dominant cerebellar ataxia. DESIGN: A genome-wide linkage analysis was performed using the Affymetrix genome-wide human single-nucleotide polymorphism array containing 909 622 single-nucleotide polymorphisms. Direct nucleotide sequencing of a candidate gene was performed. SETTING: Hokkaido University Graduate School of Medicine and Tokyo University Graduate School of Medicine. Patients  Four affected and 6 healthy individuals in a family with autosomal dominant cerebellar ataxia. RESULTS: One locus on chromosome 5q had a multipoint logarithm of odds score of 2.408, the theoretical maximum. This locus was flanked by markers rs681591 and rs32582 and includes PPP2R2B (protein phosphatase 2, regulatory subunit B, beta isoform), the causative gene of autosomal dominant spinocerebellar ataxia 12 (SCA12). However, unlike SCA12, no CAG repeat expansions in the promoter region and no nucleotide substitution or insertion-deletion mutations in the exons of the PPP2R2B gene were found. CONCLUSION: Autosomal dominant cerebellar ataxia mapping to 5q31-q33.1 has no CAG repeat expansion or other mutations of the PPP2R2B gene.

Associations between multiple system atrophy and polymorphisms of SLC1A4, SQSTM1, and EIF4EBP1 genes.

Multiple system atrophy (MSA) is an adult-onset sporadic neurodegenerative disease. Although the etiology of MSA remains obscure, recent studies suggest that oxidative stress is associated with the pathogenesis of MSA. The aim of this study was to evaluate genetic associations between the candidate genes involved in oxidative stress and MSA in a case-control study. We examined 119 Japanese patients with MSA and 123 controls, and genotyped single-nucleotide polymorphisms (SNPs) of the following eight genes: CCAAT/enhancer-binding protein homologous protein, activating transcription factor 3, CCAAT/enhancer-binding protein-beta, sequestosome 1 (SQSTM1), cysteinyl-tRNA synthetase, solute carrier family 1A4 (SLC1A4), activating transcription factor 4, and eukaryotic translation initiation factor 4E-binding protein 1 (EIF4EBP1). SLC1A4 SNP +28833 (V398I, rs759458, genotype: Pc = 0.0186, allele: Pc = 0.0303, Pc: P-value with Bonferroni correction), two major haplotypes of SLC1A4 "T-C-C-G" and "T-C-T-A" (Pc = 0.0261 and 0.000768), two-SNP haplotypes of SQSTM1 "C-T" and "A-T" (Pc = 0.0136 and 0.0369), and the most common haplotype of EIF4EBP1 "C-T-G-C" (Pc = 0.0480) showed significant associations. This study revealed genetic associations of SLC1A4, SQSTM1, and EIF4EBP1 with MSA. These results may lend genetic support to the hypothesis that oxidative stress is associated with the pathogenesis of MSA.

[Spastic paraplegia caused by a novel mutation in the spastin gene (1207C-->G, P361R)--clinical features of a patient without family history].

A 52-year-old man with no apparent family history of neurodegenerative diseases developed gait disturbance at age 47. Neurological examination at aged 52 revealed spastic paraplegia, generalized hyperreflexia, decreased of vibration sense in the lower limbs, and pollakisuria. Ocular symptoms, deafness, cerebellar ataxia, extrapyramidal signs, mental deterioration, dementia, peripheral neuropathy, retinal pigment degeneration, ichthyosis and syndactyly were absent. MRI of the brain was normal. A pure form of hereditary spastic paraplegia was diagnosed. Genetic analysis revealed a novel missense mutation in the spastin gene (1207C --> G, P361R). The clinical features of this patient were consistent with those of patient with the pure form of SPG4. Gene analysis should be considered for patients with spastic paraplegia even in the absence of any family history.

Four mutations of the spastin gene in Japanese families with spastic paraplegia.

Hereditary spastic paraplegia (HSP) is a group of genetically heterogeneous neurodegenerative disorders characterized by slowly progressive spasticity and weakness of the lower limbs. HSP is caused by failure of development or selective degeneration of the corticospinal tracts, which contain the longest axons in humans. The most common form of HSP is caused by mutations of the spastin gene (SPAST), located on chromosome 2p21-p22, which encodes spastin, one of the ATPases associated with diverse cellular activities (AAA). In this study, we detected four causative mutations of SPAST among 14 unrelated patients with spastic paraplegia. Two missense mutations (1447A-->G, 1207C-->G) and two deletion mutations (1465delT, 1475-1476delAA) were located in the AAA cassette region. Three of these four mutations were novel. Previous reports and our results suggest that the frequency of SPAST mutations is higher among Japanese patients with autosomal dominant HSP, although SPAST mutations are also observed in patients with sporadic spastic paraplegia.