Pulmonary outcome measures in long-term survivors of infantile Pompe disease on enzyme replacement therapy: A case series

Objectives: To report the respiratory function of school-aged children with infantile Pompe disease (IPD) who started enzyme replacement therapy (ERT) in infancy and early childhood.

Study design: This is a retrospective chart review of pulmonary function tests of: (a) patients with IPD 5 to 18 years of age, (b) who were not ventilator dependent, and (c) were able to perform upright and supine spirometry. Subjects were divided into a younger (5-9 years) and older cohort (10-18 years) for the analysis. Upright and supine forced vital capacity (FVC), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP) were analyzed.

Results: Fourteen patients, all cross-reactive immunologic material (CRIM)-positive, met the inclusion criteria and were included in this study. Mean upright and supine FVC were 70.3% and 64.9% predicted, respectively, in the 5- to 9-year-old cohort; and 61.5% and 52.5% predicted, respectively, in the 10- to 18-year-old group. Individual patient trends showed stability in FVC overtime in six of the 14 patients. MIPs and MEPs were consistent with inspiratory and expiratory muscle weakness in the younger and older age group but did not decline with age.

Conclusion: Data from this cohort of CRIM-positive patients with IPD showed that ERT is able to maintain respiratory function in a subgroup of patients whereas others had a steady decline. There was a statistically significant decline in FVC from the upright to a supine position in both the younger and older age groups of CRIM-positive ERT-treated patients. Before ERT, patients with IPD were unable to maintain independent ventilation beyond the first few years of life.