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Abstract 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.

Background: Use of non-vitamin K antagonist oral anticoagulants (NOACs) for stroke prevention in non-valvular atrial fibrillation (NVAF) is common and significantly reduces stroke occurrence. Yet little is known about patients who have a stroke despite treatment. Objective: The aim of this work was to study the epidemiology of patients with stroke despite being treated with NOACs. Methods: We identified a cohort of patients with NVAF admitted to the United Christian Hospital for acute ischemic stroke (AIS) or transient ischemic attack (TIA) while on NOACs. The baseline characteristics, type of NOAC, compliance, duration of use, and dosage were reviewed. Results: Of 2,090 patients admitted for AIS/TIA from 2012 to 2019, 143 were on NOACs before the index episode. After excluding patients with non-compliance and incomplete data, 109 patients were included in the analysis; 65.1% were female and 79.8% were never smokers, with a mean age of 78 years. The mean CHA2DS2-VASc score was 5; 83.5% had hypertension, 59.3% had hyperlipidemia, and 30.3% had diabetes mellitus. Overall, 52.9% presented with lacunar syndrome, suggesting an atherosclerotic cause of stroke. However, their risk factor control was unexpectedly good; none had HbA1c >7% and only 23.9% had a low-density lipoprotein cholesterol level higher than 2.6 mmol/L. Conclusions: Stroke developed in NVAF patients despite being on NOACs, with the majority being female, older, and hypertensive. Surprisingly, in general they had reasonable lipid and diabetic control.