AB084. Cause of death and clinical characteristics of 34 mortality patients with mucopolysaccharidosis II in Taiwan, 1995-2012
Hsiang-Yu Lin1,2,3,4,5, Chih-Kuang Chuang3,6,7, Ming-Ren Chen1,2,4, Shio Jean Lin8, Pao Chin Chiu9,10, Dau-Ming Niu5,11, Fuu-Jen Tsai12, Wuh-Liang Hwu13, Yin-Hsiu Chien13, Ju-Li Lin14, Shuan-Pei Lin1,2,3,4,15
Background and objective: Mucopolysaccharidosis type II (MPS II; Hunter syndrome; OMIM +309900) is an X-linked recessive, multisystemic lysosomal storage disorder caused by iduronate-2-sulfatase (I2S) deficiency, which catalyzes a step in the catabolism of glycosaminoglycans (GAGs). It leads to accumulation of GAGs in the lysosomes of many organs and tissues, causing progressive cellular dysfunction. MPS II has a variable age of onset and variable rate of progression. In Asian countries, there is a relatively higher incidence of MPS II compared to other types of MPS. The study aims to delineate the cause of death and natural history of Taiwanese patients with MPS II.
Methods: A retrospective analysis was carried out of 34 Taiwanese MPS II patients who died between 1995 and 2012. The clinical characteristics, medical records, age at death, and cause of death were evaluated to better understand the natural progression of this disease.
Results: Among these 34 mortality patients, 31 were severe form with significant cognitive impairment, two were mild form without cognitive involvement, and one was intermediate form. The mean age at death was 14.2±4.2 years. The mean ages at onset of symptoms and confirmed diagnosis were 2.5±2.1 and 4.8±3.1 years, respectively (n=32). The mean gestational age and birth weight were 39.2±1.8 weeks and 3,522±581 grams, respectively (n=24). The mean age at death of 31 severe form was 13.2±3.2 years, compared with 22.6±4.3 years of three patients with mild or intermediate forms (P<0.001). Among the 27 patients with available records of primary cause of death, respiratory failure was the leading cause (70%), followed by cardiac failure (22%), post-traumatic organ failure (4%), and infection (sepsis) (4%). Age at onset of symptoms was positively correlated with life expectancy (P<0.01). The longevity also increased gradually over time between 1995 and 2012 (P<0.05).
Conclusions: The life expectancy of Taiwanese MPS II patients has improved in recent decades. With the implementation of National Health Insurance in Taiwan since 1995, it is possible that referral of patients to specialist and improvement in multidisciplinary care underlie this trend. These findings can be used to develop quality of care strategies for these patients.
Keywords: Cause of death; Hunter syndrome; mortality; mucopolysaccharidosis II (MPS II); Taiwan