p.[G576S; E689K]: pathogenic combination or polymorphism in Pompe disease?
We discuss four cases of acid alpha-glucosidase deficiency (EC, 3.2.1.3/20) without evident symptoms of Pompe disease (OMIM No 232300) in individuals of Asian descent. In three cases, the deficiency was associated with homozygosity for the sequence variant c.[1726G>A; 2065G>A] in the acid alpha-glucosidase gene (GAA) translating into p.[G576S; E689K]. One of these cases was a patient with profound muscular atrophy, another had cardio-myopathy and the third had no symptoms. The fourth case, the mother of a child with Pompe disease, was compound heterozygote for the GAA sequence variants c.[1726G>A; 2065G>A]/c.2338G>A (p.W746X) and had no symptoms either. Further investigations revealed that c.[1726A; 2065A] is a common GAA allele in the Japanese and Chinese populations. Our limited study predicts that approximately 4% of individuals in these populations are homozygote c.[1726A; 2065A]. The height of this figure in contrast to the rarity of Pompe disease in Asian populations and the clinical history of the cases described in this paper virtually exclude that homozygosity for c.[1726A; 2065A] causes Pompe disease. As c.[1726A; 2065A] homozygotes have been observed with similarly low acid alpha-glucosidase activity as some patients with Pompe disease, we caution they may present as false positives in newborn screening programs especially in Asian populations.
Kroos
Marian A
MA
Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands.
Mullaart
Reinier A
RA
Van Vliet
Laura
L
Pomponio
Robert J
RJ
Amartino
Hernan
H
Kolodny
Edwin H
EH
Pastores
Gregory M
GM
Wevers
Ron A
RA
Van der Ploeg
Ans T
AT
Halley
Dicky J J
DJ
Reuser
Arnold J J
AJ
D000293:Adolescent; D000328:Adult; D002478:Cells, Cultured; D002648:Child; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism; D006009:Glycogen Storage Disease Type II / Q000201:enzymology / Q000453:epidemiology / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D007962:Leukocytes / Q000166:cytology / Q000378:metabolism; D008214:Lymphocytes / Q000166:cytology / Q000378:metabolism; D008297:Male; D009132:Muscles / Q000166:cytology / Q000378:metabolism; D011110:Polymorphism, Genetic; D000520:alpha-Glucosidases / Q000235:genetics*
D006003:Glycogen; C509951:GAA protein, human; D000520:alpha-Glucosidases