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.

Guillain-Barré syndrome in children - High occurrence of Miller Fisher syndrome in East Asian region.

BACKGROUND: Guillain-Barré syndrome (GBS) is a rare acquired immune-mediated polyneuropathy. Updated population-based data concerning paediatric GBS is needed. METHODS: Paediatric patients aged below 18 years diagnosed with GBS between 2009 and 2018 in all 11 paediatric departments in Hong Kong were identified from the Hong Kong Hospital Authority Clinical Data Analysis and Reporting System. The collected data from medical health records were reviewed by paediatric neurologist from each department. Estimated incidence of paediatric GBS was calculated. We also compared our findings with other paediatric GBS studies in Asia. RESULTS: 63 subjects of paediatric GBS were identified, giving an estimated annual incidence of 0.62 per 100,000 population. Half of the subjects had acute inflammatory demyelinating polyneuropathy (AIDP) (n = 31; 49.2%), one quarter had Miller Fisher Syndrome (MFS) (n = 16; 25.4%), one-fifth had axonal types of GBS (n = 12; 19.0%), and four were unclassified. Paediatric subjects with axonal subtypes of GBS compared to the other 2 subtypes, had significantly higher intensive care unit (ICU) admission rates (p = 0.001) and longest length of stay (p = 0.009). With immunomodulating therapy, complete recovery was highest in those with MFS (100%), followed by AIDP (87.1%) and axonal GBS (75%). Our study also confirms a higher MFS rate for paediatric GBS in East Asia region and our study has the highest MFS rate (25.4%). CONCLUSION: Our population-based 10-year paediatric GBS study provides updated evidence on estimated incidence, healthcare burden and motor outcome of each subtype of paediatric GBS and confirmed a higher occurrence of paediatric MFS in East Asia.

Anti-N-methyl-d-aspartate receptor encephalitis in children: Incidence and experience in Hong Kong.

AIM: The study aims to analyze the incidence, clinical features, investigation findings and treatment outcomes of anti-N-methyl-d-aspartate receptor encephalitis in children from Hong Kong. METHOD: A retrospective study was carried out on paediatric patients diagnosed with anti-NMDAR encephalitis in Hong Kong from January 2009 to December 2015. RESULTS: Fifteen patients (67% female, 93% Chinese) were identified over seven years and the estimated incidence in Hong Kong was 2.2/million children per year (95% CI 1.2-3.6). The median age of presentation was 12 years (range 1-17 years). The most common symptom groups observed were abnormal psychiatric behavior or cognitive dysfunction (14/15, 93%) and seizures (14/15, 93%), followed by speech dysfunction (13/15, 87%), movement disorders (12/15, 80%), decreased level of consciousness (10/15, 67%) and autonomic dysfunction or central hypoventilation (5/15, 33%). The median number of symptom groups developed in each patient was 5 (range 3-6). All patients were treated with intravenous immunoglobulin and/or steroids. Three patients (20%) with more severe presentation required additional plasmapheresis and rituximab. Outcome was assessable in 14 patients. Among those eleven patients who had only received intravenous immunoglobulin and/or steroids, nine patients (82%) achieved full recovery. One patient (9%) had residual behavioral problem, while another one (9%) who developed anti-NMDAR encephalitis after herpes simplex virus encephalitis was complicated with dyskinetic cerebral palsy and epilepsy. Among those three patients who required plasmapheresis and rituximab, one (33%) had full recovery and two (66%) had substantial recovery. The median duration of follow up was 20.5 months (range 3-84 months). CONCLUSION: Anti-NMDAR encephalitis is an acquired, severe, but potentially treatable disorder. Ethnicity may play a role in the incidence of anti-NMDAR encephalitis and we have provided a local incidence with the majority of patients being Chinese. The diagnosis of anti-NMDAR encephalitis should be considered in children presenting with a constellation of symptoms including psychiatric and neurological manifestations. Patients may respond to first line immunotherapy. For those who do not, second line therapy is indicated in order to achieve a better outcome.

Isolated adrenocorticotropin deficiency in a child with Kabuki syndrome.

A 6 year-old Chinese boy with Kabuki syndrome presented with hypoglycemic seizure. He was diagnosed to have isolated adrenocorticotropin deficiency. To our knowledge, this is the first case of Kabuki syndrome with isolated adrenocorticotropin deficiency in the literature.

Internal consistency and test-retest reliability of the Chinese version of the self-report health-related quality of life measure for children and adolescents with epilepsy.

PURPOSE: The aim of this validation study was to evaluate the internal consistency (internal reliability) and test-retest reliability (external reliability) of the Chinese version of the self-report health-related quality of life measure for children and adolescents with epilepsy. METHODS: Children and adolescents with epilepsy between the ages of 8 and 18 years were conveniently sampled in two regional hospitals in Hong Kong. They were requested to complete the 25-item questionnaire twice, with a test-retest interval of 10 to 14 days. Internal consistency and test-retest reliability were measured with Cronbach's alpha coefficient and the intraclass correlation coefficient, respectively. RESULTS: A sample of 50 patients completed the first questionnaire. Internal consistency was adequate on four of five subscales and marginal in the remaining one. Forty-two subjects repeated the questionnaire. The test-retest reliability was acceptable for all five subscales. CONCLUSIONS: The Chinese version of the health-related quality of life measure for children and adolescents with epilepsy demonstrated acceptable internal consistency and test-retest reliability. Further studies are required to study other psychometric properties such as construct validity and factor analysis.