Huntington's disease prevalence in Asia: a systematic review and meta-analysis.

Abstract

The epidemiological studies on Huntington's disease (HD) in the Asian population suggest that prevalence rates are significantly lower than in the Western population. We conducted a systematic review of epidemiological studies of HD in Asia to compare the level of impact of the disease on the Asian population. Original articles and reviews about HD prevalence in the Asian population were found through databases such as Embase, Medline, and PsychInfo. Relevant articles were analysed by scrutinising of references, including specific key words. A meta-analysis was performed on prevalence rates to find the degree of similarities with I2. Point Prevalence was measured as the number of people affected by HD in a 100,000 population and expressed as Point Prevalence (PP)= Number of people affected/100,000 with 95% Confidence Intervals (CI95). Results from the random-effect meta-analysis show the highest point prevalence of HD in the Middle East with PP=4.0 (CI95=2.90-5.30). The lowest point prevalence was found in the Chinese population with PP=0.25 (CI95=0.16-0.36). Europe remains at a high prevalence compared to Asian countries with PP=1.00 (CI95=0.82-1.19). The overall prevalence in Asia is PP=0.70 (CI95=0.44-1.0). Our study reveals that HD disease affects the population of Asia to a lesser extent than in Europe. The plausible explanation for differences in prevalence is that in some countries, the affected individuals will not self-refer to HD screening for fear of social stigma, negative influence in marriage, and lack of genetic and neurological testing. Another explanation is that studies that used genetic testing exclusively were able to identify the CAG repeats, subgroups of CAG repeat A1 & A2, and haplogroup C, which has less predisposition to high HD prevalence in Asians compared to the Caucasian population.