RECENT FINDINGS: The spectrum of paraneoplastic autoimmune disorders has been expanding with the discovery of new antibodies against cell surface and intracellular antigens. Many of these paraneoplastic autoimmune disorders manifest as a form of movement disorder. With the discovery of new neuronal antibodies, an increasing number of idiopathic or neurodegenerative movement disorders are now being reclassified as immune-mediated movement disorders. These include anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis which may present with orolingual facial dyskinesia and stereotyped movements, CRMP-5 IgG presenting with chorea, anti-Yo paraneoplastic cerebellar degeneration presenting with ataxia, anti-VGKC complex (Caspr2 antibodies) neuromyotonia, opsoclonus-myoclonus-ataxia syndrome, and muscle rigidity and episodic spasms (amphiphysin, glutamic acid decarboxylase, glycine receptor, GABA(A)-receptor associated protein antibodies) in stiff-person syndrome.
SUMMARY: Movement disorders may be a presentation for paraneoplastic autoimmune disorders. Recognition of these disorders and their common phenomenology is important because it may lead to the discovery of an occult malignancy.
METHODS: (1) A population-based study was undertaken to estimate NMOSD prevalence in the multi-ethnic Penang Island, Malaysia, comprising Chinese, Malays, and Indians. Medical records of NMOSD patients followed up at the Penang General Hospital (the neurology referral centre in Penang Island) were reviewed. The 2015 diagnostic criteria of the International Panel for NMO Diagnosis were used for case ascertainment. (2) A review of population-based prevalence studies of NMOSD worldwide was carried out. PubMed and conference proceedings were searched for such studies.
RESULTS: Of the 28 NMOSD patients, 14 were residents of Penang Island on prevalence day [13 (93%) Chinese and one (7%) Malay]. All 14 patients were females and aquaporin 4 seropositive. The prevalence of NMOSD in Penang Island was 1.99/100,000 population; according to ethnicities, the prevalence in Chinese was significantly higher than in Malays (3.31/100,000 vs 0.43/100,000, respectively, p = 0.0195).
CONCLUSION: Based on our and other population-based studies, among Asians, East Asian origin populations (Chinese and Japanese) appear to have higher NMOSD prevalence than other Asian ethnic groups. Worldwide, Blacks seem to have the highest NMOSD prevalence. More studies in different geographical regions and ethnic groups will be useful to further inform about potential factors in NMOSD pathogenesis.
MATERIALS AND METHODS: Eight hundred and twenty-eight subjects (404 PD patients, and 424 age and gender-matched control subjects without neurological disorders) were recruited. Genotyping was done by Taqman® allelic discrimination assay on an Applied Biosystems 7500 Fast Real-Time PCR machine.
RESULTS: The heterozygous A419V genotype was found in only 1 patient with PD, compared to 3 in the control group (0.4% vs 1.3%), giving an odds ratio of 0.35 (95% confidence interval (CI), 0.01 to 3.79; P = 0.624).
CONCLUSION: A419V is not an important LRRK2 risk variant in our Asian cohort of patients with PD. Our data are further supported by a literature review which showed that 4 out of 6 published studies reported a negative association of this variant in PD.
METHODS: Cases (523) which conformed to the United Kingdom PD Brain Bank Criteria for PD were recruited through trained neurologists and age- and ethnically matched controls (491) were individuals free of any neurological disorder. The N551K and R1398H mutations were genotyped using the Taqman SNP genotyping assay.
RESULTS: A significant protective association for N551K was found in those of Malay ancestry, with a protective trend seen for R1398H. A meta-analysis of Chinese individuals in this cohort with other published cohorts of Chinese ancestry indicated a significant protective role for N551K and R1398H.
CONCLUSION: This study reports that the N551K-R1398H haplotype is also relevant to the Malaysian population, with a significant protective effect found in those of Malay and Chinese ancestries.