Angelman syndrome in Hong Kong Chinese: A 20 years' experience.

AS(OMIM #105830) is a neurodevelopmental disease that characterized by severe intellectual disability, lack of speech, happy disposition, ataxia, epilepsy and distinct behavioural profile. A tertiary wide study was performed in Hong Kong with aim to examine the clinical and molecular features, genotype-phenotype correlation of the Angelman syndrome (AS) patients. There were total 55 molecularly confirmed AS between January 1995 to September 2015 for review. 65.5% of them were caused by maternal microdeletion, 10.9% by paternal uniparental disomy, 3.6% by imprinting center defect and 14.5% by UBE3A gene mutation. Genotype-phenotype correlation showed epilepsy and microcephaly is more common in microdeletion type as compared with non-microdeletional type. We have concluded that the incidence rate, clinical features and underlying genetic mechanisms in Hong Kong Chinese were comparable with other western populations. The overall average age of diagnosis in this cohort was 6.2 years old (95% C.I was 5.0-7.5 years old). It is hope that by increasing awareness and early referral could result in early diagnosis and better management for AS patient.