Early cognitive development in children with infantile Pompe disease

This report describes the cognitive development of 17 children with infantile Pompe disease who participated in a 52-week clinical trial of enzyme replacement therapy (ERT) via biweekly infusion of Myozyme® (alglucosidase alfa). Subjects were six months of age or younger (adjusted for gestational age) upon initiation of ERT. The Mental Scale of the Bayley Scales of Infant Development-Second Edition (BSID-II) was administered to obtain a Mental Development Index (MDI) at baseline and weeks 12, 26, 38, and 52 of ERT to assess cognitive development in this treated cohort. Data regarding motor development were also obtained at the same visits and these were used to determine correlations between cognitive and motor development. Over the course of the study, two subgroups of subjects emerged: high responders who were sitting independently and/or ambulating by week 52 (n=13) and limited responders who showed minimal motor gains throughout the first year of ERT (n=4). In the high responder group, MDI scores on the BSID-II remained stable throughout the study and were within normal limits. Positive correlations between cognitive and motor development were also present. These data suggest that the cognitive function of infants up to 18 months of age with Pompe disease is unaffected by the possible presence of glycogen in the central nervous system. Continued investigation of the cognitive development of older survivors is warranted.