**2.1 Epidemiology**

This disease entity was believed to affect Asian heritage, given their genetic predisposition. However, it is now a well-known fact that this disease entity can affect American and European ethnicities [3]. This disease has a bimodal distribution of age-specific incidence rates with two peaks in the age groups of 5 years in children andmid-40s in the adults [3, 4]. It is twice more common in females as in males [3]. The incidence estimates of 0.35–0.54/100,000 are found in the Japanese and Korean populations [5]. An incidence of 0.086 cases per 100,000 persons inAmericans, incidence-rate ratios are 4.6 for Asian Americans, 2.2 for blacks, and 0.5 for Hispanics [6].
