title: Rapid progressive course of later-onset Pompe disease in Chinese patients.
abstract: BACKGROUND
  Pompe disease presents with a wide variety of phenotypes ranging from a fatal disease in infancy (the infantile-onset form) to other milder later-onset forms. Currently, the clinical manifestations in Chinese patients with later-onset Pompe disease are still not well understood.
  
  
  METHODS
  Fifteen Chinese patients who were clinically diagnosed with Pompe disease at later than one year of age at the National Taiwan University Hospital from 1993 to 2009 were included in this study. Confirmatory diagnosis included both biochemical and molecular tests. Patient outcomes after recombinant human acid α-glucosidase (GAA) therapy were also evaluated by assessing the percentage of predicted forced vital capacity in the upright position, hours of daily ventilator use, and the functional status change using Walton Gardner Medwin Scale.
  
  
  RESULTS
  The median age at symptom onset was 15 (12-35)years, and the median age at diagnosis was 21 (10-38)years. At the time of diagnosis or shortly after, 8 patients (53%) required mechanical ventilation. A quadriceps muscle biopsy from a 13-year-old boy already showed extensive glycogen storage and muscle fiber destruction. Mutation analysis revealed that the two dual mutations in the GAA gene c.[1935C>A; 1726G>A] (p.[D645E; G576S]) and c.[2238G>C; 1726G>A] (p.[W746C; G576S]) represented 66.5% of the mutated chromosomes. Using mutagenesis, we showed that the p.G576S pseudodeficiency mutation significantly decreased the residual enzyme activity of p.W746C. Most patients responded poorly to recombinant human GAA.
  
  
  CONCLUSIONS
  Chinese patients with later-onset Pompe disease often showed onset of symptoms in their second decade of life with rapid disease progression, which is probably due to a specific pattern of GAA gene mutation. Therefore, early diagnosis and early treatment would be necessary to improve the prognosis of these patients.
authors.affiliation: Department of Neurology, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan.
authors.forename: Chih-Chao
authors.initials: CC
authors.lastname: Yang
authors.forename: Yin-Hsiu
authors.initials: YH
authors.lastname: Chien
authors.forename: Ni-Chung
authors.initials: NC
authors.lastname: Lee
authors.forename: Shu-Chuan
authors.initials: SC
authors.lastname: Chiang
authors.forename: Shuan-Pei
authors.initials: SP
authors.lastname: Lin
authors.forename: Yung-Ting
authors.initials: YT
authors.lastname: Kuo
authors.forename: Shun-Sheng
authors.initials: SS
authors.lastname: Chen
authors.forename: Yuh-Jyh
authors.initials: YJ
authors.lastname: Jong
authors.forename: Wuh-Liang
authors.initials: WL
authors.lastname: Hwu
mesh_terms: D000293:Adolescent; D000328:Adult; D044466:Asian People; D056947:Enzyme Replacement Therapy; D006009:Glycogen Storage Disease Type II / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology*; D006801:Humans; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation / Q000235:genetics; D012121:Respiration, Artificial; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013624:Taiwan; D016896:Treatment Outcome; D000520:alpha-Glucosidases / Q000008:administration & dosage / Q000235:genetics* / Q000627:therapeutic use*
chemical_list: C509951:GAA protein, human; D000520:alpha-Glucosidases