Nishizawa, Masatoyo

Abstract To elucidate the molecular basis of multiple system atrophy (MSA), a neurodegenerative disease, we conducted a genome-wide association study (GWAS) in a Japanese MSA case/control series followed by replication studies in Japanese, Korean, Chinese, European, and North American samples. In the GWAS stage, rs2303744 on chromosome 19 showed a suggestive association (P = 6.5 × 10− 7) that was replicated in additional Japanese samples (P = 2.9 × 10− 6, odds ratio (OR) = 1.58; 95% confidence interval (CI), 1.30–1.91), and then confirmed as highly significant in a meta-analysis of East Asian population data (P = 5.0 × 10− 15, OR = 1.49; 95% CI 1.35–1.65). The association of rs2303744 with MSA remained significant in combined European/North American samples (P = 0.017, OR = 1.12; 95% CI 1.02–1.23) despite allele frequencies being quite different between these populations. rs2303744 leads to an amino acid substitution in PLA2G4C that encodes the cPLA2γ lysophospholipase/transacylase. The cPLA2γ-Ile143 isoform encoded by the MSA risk allele has significantly decreased transacylase activity compared with the alternate cPLA2γ-Val143 isoform, and may perturb membrane phospholipids and promote oligodendroglial pathology.

Background and purpose The clinical characteristics of colony stimulating factor 1 receptor ( CSF 1R) related adult‐onset leukoencephalopathy with axonal spheroids and pigmented glia ( ALSP ) have been only partially elucidated. Methods Clinical data from CSF 1R mutation carriers who had been seen at our institutions or reported elsewhere were collected and analysed using a specific investigation sheet to standardize the data. Results In all, 122 cases from 90 families with CSF 1R mutations were identified. The mean age of onset was 43 years (range 18–78 years), the mean age at death was 53 years (range 23–84 years) and the mean disease duration was 6.8 years (range 1–29 years). Women had a significantly younger age of onset than men (40 vs. 47 years, P = 0.0006, 95% confidence interval 3.158–11.177). There was an age‐dependent penetrance that was significantly different between the sexes ( P = 0.0013). Motor dysfunctions were the most frequent initial symptom in women whose diseases began in their 20s. Thinning of the corpus callosum, abnormal signalling in pyramidal tracts, diffusion‐restricted lesions and calcifications in the white matter were characteristic imaging findings of ALSP . The calcifications were more frequently reported in our case series than in the literature (54% vs. 3%). Seventy‐nine per cent of the mutations were located in the distal part of the tyrosine kinase domain of CSF 1R (102 cases). There were no apparent phenotype−genotype correlations. Conclusions The characteristics of ALSP were clarified. The phenotype of ALSP caused by CSF 1R mutations is affected by sex.