title: Low bone mass in Pompe disease: muscular strength as a predictor of bone mineral density.
abstract: Pompe disease is an inherited metabolic myopathy caused by deficiency of acid alpha-glucosidase. The introduction of enzyme replacement therapy as treatment for the disease may change prospects for patients and may require that more attention be paid to co-morbidities such as osteoporosis.
  
  
  METHODS
  Bone mineral status was assessed in children and adults with Pompe disease and compared with reference values by means of dual energy X-ray absorptiometry (DXA) technology (GE Lunar DPX, GE Health Care). Bone mineral density (BMD) of the total body and the lumbar spine (L2-L4) was measured in adults and children; BMD of the femoral neck was measured in adults only. Exclusion criteria were: age<4 years, severe contractures, and inability to transfer the patient.
  
  
  RESULTS
  46 patients were enrolled in the study; 36 adults and 10 children. The BMD was significantly lower in Pompe patients than in healthy individuals. Sixty-seven percent of patients had a BMD Z-score below -1, 26% were classified as osteoporosis/low bone mass for chronological age (T-score<-2.5 in adults or Z-score<-2 in children), 66% had a BMD Z-score below -1 of the femoral neck, and 34% had a BMD Z-score below -1 for the lumbar spine. Osteoporosis/low bone mass for chronological age was more frequent in patients who were wheelchair-bound, but was also observed in ambulant patients. We found a significant correlation between proximal muscle strength and total body BMD. Of the 10 children, 8 (all four patients with the classic infantile form) had a low BMD.
  
  
  CONCLUSIONS
  Low BMD is a frequent finding in patients with Pompe disease and may be causally related to decreased proximal muscle strength. BMD should be monitored at regular intervals. Children deserve specific attention.
authors.affiliation: Department of Pediatrics, Division of Metabolic Diseases and Genetics, Center for Lysosomal and Metabolic Diseases, Erasmus MC University Medical Center, Rotterdam, The Netherlands. l.vandenberg@erasmusmc.nl
authors.forename: Linda E M
authors.initials: LE
authors.lastname: van den Berg
authors.forename: Adrienne A
authors.initials: AA
authors.lastname: Zandbergen
authors.forename: Carine I
authors.initials: CI
authors.lastname: van Capelle
authors.forename: Juna M
authors.initials: JM
authors.lastname: de Vries
authors.forename: Wim C
authors.initials: WC
authors.lastname: Hop
authors.forename: Johanna M
authors.initials: JM
authors.lastname: van den Hout
authors.forename: Arnold J J
authors.initials: AJ
authors.lastname: Reuser
authors.forename: M Carola
authors.initials: MC
authors.lastname: Zillikens
authors.forename: Ans T
authors.initials: AT
authors.lastname: van der Ploeg
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D000328:Adult; D015519:Bone Density; D002648:Child; D002675:Child, Preschool; D005260:Female; D006009:Glycogen Storage Disease Type II / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D000520:alpha-Glucosidases / Q000172:deficiency
chemical_list: D000520:alpha-Glucosidases