J Korean Neurol Assoc.  2021 May;39(2):75-81. 10.17340/jkna.2021.2.3.

Multicenter Targeted Population Screening of Late Onset Pompe Disease in Unspecified Myopathy Patients in Korea

Affiliations
  • 1Department of Neurology, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
  • 2Department of Neurology, Pusan National University Yangsan Hospital, Pusan National University School of Medicine, Yangsan, Korea
  • 3Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
  • 4Department of Neurology, Sungkyunkwan University School of Medicine, Seoul, Korea
  • 5Department of Neurology, Cheonan Hospital, Soonchunhyang University College of Medicine, Cheonan, Korea
  • 6Department of Neurology, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea
  • 7Department of Neurology, Chonnam National University Medical School, Gwangju, Korea
  • 8Department of Neurology, Pusan National University School of Medicine, Busan, Korea
  • 9Department of Neurology, School of Medicine, Kyungpook National University, Daegu, Korea
  • 10Kim Sook Za's Children Hospital, Cheongju, Korea
  • 11Department of Neurology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea

Abstract

Background
Pompe disease is a rare autosomal recessive disorder caused by the deficiency of a lysosomal enzyme, acid alpha-glucosidase (GAA). Early diagnosis and initiation of treatment with enzyme replacement therapy have remarkable effects on the prognosis of Pompe disease. We performed the expanded screening for late onset Pompe disease (LOPD) at eight centers in Korea.
Methods
From September 1, 2015, GAA activity were measured from both dried blood spot (DBS) and mixed leukocyte for 188 available patients. For 12 patients with low GAA activity, we performed Sanger sequencing of GAA gene.
Results
Among 188 patients, 115 were males. The mean of age of symptom onset and diagnosis were 34.3 years and 41.6 years. Among 12 patients with decreased GAA activity, two patients were confirmed to have LOPD with genetic test (c.1316T>A [p.M439K] + c.2015G>A [p.R672Q], c.1857C>G [p.S619R] + c.546G>C [leaky splicing]). Other two patients had homozygous G576S and E689K mutation, known as pseudodeficiency allele.
Conclusions
This study is expanded study of LOPD screening for targeted Korean population. We found two patients with LOPD, and the detection rate of LOPD is 1.06%. With application of modified GAA cutoff value (0.4), which was previously reported, there were no false positive results of GAA activity test using DBS. Therefore, it could be an appropriate screening test for LOPD in especially East-Asian population, in which pseudodeficiency allele is frequent.

Keyword

Glycogen storage disease type II; Alpha-glucosidases; Enzyme assays; Genetic testing
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