Mitochondrial diseases in Hong Kong: prevalence, clinical characteristics and genetic landscape.

OBJECTIVE: To determine the prevalence of mitochondrial diseases (MD) in Hong Kong (HK) and to evaluate the clinical characteristics and genetic landscape of MD patients in the region. METHODS: This study retrospectively reviewed the phenotypic and molecular characteristics of MD patients from participating public hospitals in HK between January 1985 to October 2020. Molecularly and/or enzymatically confirmed MD cases of any age were recruited via the Clinical Analysis and Reporting System (CDARS) using relevant keywords and/or International Classification of Disease (ICD) codes under the HK Hospital Authority or through the personal recollection of treating clinicians among the investigators. RESULTS: A total of 119 MD patients were recruited and analyzed in the study. The point prevalence of MD in HK was 1.02 in 100,000 people (95% confidence interval 0.81-1.28 in 100,000). 110 patients had molecularly proven MD and the other nine were diagnosed by OXPHOS enzymology analysis or mitochondrial DNA depletion analysis with unknown molecular basis. Pathogenic variants in the mitochondrial genome (72 patients) were more prevalent than those in the nuclear genome (38 patients) in our cohort. The most commonly involved organ system at disease onset was the neurological system, in which developmental delay, seizures or epilepsy, and stroke-like episodes were the most frequently reported presentations. The mortality rate in our cohort was 37%. CONCLUSION: This study is a territory-wide overview of the clinical and genetic characteristics of MD patients in a Chinese population, providing the first available prevalence rate of MD in Hong Kong. The findings of this study aim to facilitate future in-depth evaluation of MD and lay the foundation to establish a local MD registry.

Association between high cumulative dose of benzodiazepine in Chinese patients and risk of dementia: a preliminary retrospective case-control study.

BACKGROUND: Evidence describing the association between high-dose benzodiazepine use and dementia has been conflicting. Most previous studies involved Caucasian populations, with only limited data on Chinese subjects. Possible differences exist between Chinese and Caucasian populations with regard to metabolism and prescription practice. This study aimed to assess the association between high-dose benzodiazepine use and dementia in a Chinese population. METHOD: A retrospective case-control study was carried out in all public hospitals under the Hong Kong Hospital Authority Hong Kong West Cluster between 2000 and 2015. The study recruited 273 Chinese adults (91 cases, 182 controls) aged 75 and over, with at least 6 years of follow-up data. Each dementia case was matched with two controls according to sex, age group, and duration of follow-up. The number of patients with benzodiazepine ever-use and the exposure density based on the prescribed daily doses were assessed. Prescribed daily doses were categorized as either <1096 or ≥1096. Odds ratios and 95% confidence intervals were computed by multivariate analysis. RESULTS: The difference in exposure density between the dementia and control groups was statistically significant between prescribed daily doses <1096 and ≥1096 (P = 0.02). There were two multivariate analyses models; one factored in depression (model 1), and the other (model 2) did not. Model 2 showed a statistically significant association (odds ratio = 1.71, 95% confidence intervals = 1.02-2.89, P = 0.04) between benzodiazepine exposure density and dementia. CONCLUSION: High-dose benzodiazepine use may be associated with dementia in the Chinese population. Prospective studies are required.