CRIM Status and Follow-up of Individuals with Pompe Disease

Infantile-onset Pompe disease is an inherited disorder that is normally diagnosed within the first months of life. It is caused by lack of or defect in an enzyme (a special protein that carries out normal chemical reactions within the body) called acid alpha-glucosidase (GAA). GAA normally breaks down glycogen (stored sugar) in lysosomes (the part of the cell that digests food and other chemicals). Pompe disease is one of many lysosomal storage diseases (LSDs). LSDs are diseases caused by the malfunction of the lysosome or one of their digestive enzymes. Patients with Pompe disease cannot break down lysosomal glycogen. This causes glycogen to build up and damage cells throughout the body, especially in the heart and muscles. Current treatment for Pompe disease involves enzyme replacement therapy (ERT). In this treatment, the drug alglucosidase alfa (Myozyme) is put into your blood. The drug provides a form of the GAA enzyme to replace the enzyme that is missing or not working properly in the patient's blood. This treatment has allowed babies to live longer and achieve developmental milestones. In this study, researchers will learn about the patient's ability to tolerate ERT. Cross-Reactive Immunological Material (CRIM) is a measurement of natural GAA production. A patient's CRIM status (either positive or negative) is an important factor that affects how he or she responds to ERT with Myozyme. Children who produce some natural GAA are classified as CRIM+, while children who do not produce any natural GAA are classified as CRIM-. Children who are CRIM+ generally tolerate ERT well. But, children who are CRIM-, and some children classified as CRIM+, have a poor response to ERT. Patients who have a poor response to ERT have complications because their body sees Myozyme as "foreign" and triggers an immune response to try to remove it from the body. Treatments are currently being developed to stop this immune response and prevent complications from ERT. We will enroll patients with Infantile Pompe disease in this longitudinal natural history (observational) study. The specific aims of this study are: To determine and correlate Cross-Reactive Immunological Material (CRIM) status with the GAA gene mutations found on these patients To validate an approach for determining CRIM status from whole blood sample, with the gold standard determination of CRIM status by skin fibroblasts and mutation analysis To explore the clinical treatment response and natural history of CRIM-positive and CRIM-negative Pompe disease patients with and without immune modulation To investigate the role of immune response to treatment ]]> BASELINE SUBJECT INFORMATION FOR PATIENTS WITH POMPE DISEASESUBJECT INFORMATION FOR PATIENTS WITH POMPE DISEASEConclusion of Study ParticipationInclusion criteria: Subjects will be included in this study if they meet the following inclusion criteria: Subject has a confirmed and documented diagnosis of infantile, atypical or juvenile onset Pompe disease Subject is less than 18 years of age at the time of enrollment Subjects will be allowed to participate in every other aspect of the study except from giving blood samples for blood-based CRIM analysis if: The subject has received enzyme therapy within the past 6 days. If the subject is on ERT at the time of identification, samples can instead be obtained immediately prior to their next ERT infusion, when enzyme levels are lowest (ideally 14 days after previous treatment). The subject has received a blood transfusion within the last 30 days. The blood transfusion should not affect Western blood and DNA mutation analysis. Exclusion Criteria: Subjects will be excluded from the study if 18 years of age or older.]]> Study Activated February 8, 2012 First Accrual January 12, 2008 ]]>