OBJECTIVES: Prior studies have documented that patients with classic galactosemia (CG) are at increased risk for developmental deficits despite early detection and rigorous dietary restriction of galactose. However, whether these complications progress over time has not been confirmed. Here, we explore this question using both cross-sectional and longitudinal analyses.

METHODS: 158 patients with CG, ≤30 years old, were assessed over several years using ≥1 of the following: the Developmental Profile-3 (DP3), the Adaptive Behaviors Assessment System-3 (ABAS-3), and the Vineland-3. For each assessment, we calculated mean ± standard deviation of the composite and domain-specific standard scores. 84 unaffected siblings served as controls. We compared scores by age cross-sectionally across instruments and longitudinally among those with repeated -- but differing -- measures. Of cases, 37(23.4%) completed the DP3 (mean age, 8.9 years), 103(65.2%) the ABAS3 (11.9 years), and 56(35.4%) the Vineland-3 (9.4 years).

RESULTS: As expected, all 3 instruments revealed higher prevalence of deficits among cases than controls. Specifically, composite standard scores ranged from 76.1±15.4 (DP3) to 91.8±14.7 (Vineland-3) for cases and from 99.3±14.1 (DP3) to 104.9±10.8 (Vineland-3) for controls. Domain-specific analyses also showed lower scores among cases, with the majority of those impacted scoring below average on more than one domain. Cross-sectional linear regression analyses demonstrated that, with increasing age, composite and domain-specific scores declined slightly among cases but not controls for both the ABAS-3 and Vineland-3, whereas DP3 scores decreased slightly among both cases and controls. In contrast, longitudinal analyses using ≥2 instruments did not show decline for most cases and controls.

CONCLUSIONS: Whether developmental function in CG declines over time is presently unclear. While cross-sectional analyses demonstrate declines with older age, longitudinal analyses across multiple tools , do not demonstrate worsening of deficits with time. Ongoing efforts using one standardized instrument longitudinally will allow better understanding of progression by age.