Abstract
Introduction: Cognitive impairment is a well-known complication of classical galactosemia (CG). Differences in patient characteristics and test methods have hampered final conclusions regarding the extent of intellectual disabilities in CG. The primary aim of this systematic review was to assess intellectual performance in early-treated (≤4 weeks of life) individuals with confirmed CG (defined by absent or barely detectable GALT enzyme activity and/or the presence of two null or severe missense variations), assessed with comparable test instruments. The full-scale IQ (FSIQ) was the variable of interest.
Methods: A clinical librarian developed search strategies, and two independent investigators performed the study selection, risk of bias assessment and data extraction. Individual patient data were pooled for meta-analysis using linear mixed-effect models with a random intercept per study and including covariates (age or gender) as fixed effects where appropriate.
Results: Four articles were included in this meta-analysis. Data of 87 individuals (median age 13 years, range 3–38 years) were used to assess mean FSIQ in CG. The FSIQ ranged from 47 to 122, and the mean score was 87 (95% CI, 81–94). Forty-five percent of individuals attained scores <85, almost 40% attained scores of 85–100, and a minority (15%) attained scores above 100. There was no significant correlation between FSIQ and age.
Conclusions: Results from this meta-analysis fortify conclusions from previous studies that early-treated individuals with CG are at risk for having impaired cognitive abilities. However, IQ varies considerably between affected individuals.
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The authors would like to thank Arnold G. E. Leenders for creating the search strategies.
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Communicated by: Ivo Bari, M.D., Ph.D., Professor of Pediatrics
Take-Home Message
Early-treated individuals with classical galactosemia are at risk for having impaired cognitive abilities, but FSIQ scores vary considerably between affected individuals.
Contributions of Individual Authors
All authors participated in analysis and interpretation of data and drafting the article and revising it critically for important intellectual content. Annet M. Bosch, Johanna H. van der Lee, Susan E. Waisbren and Lindsey Welling participated additionally in conception and design of the study.
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Annet M. Bosch.
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Annet M. Bosch is in receipt of research grants from Nutricia and was a member of an advisory board for Nutricia, Merck Serono and BioMarin.
Kevin M. Antshel declares that he has no conflict of interest.
Hugh-Owen Colhoun declares that he has no conflict of interest.
Matthias Gautschi declares that he has no conflict of interest.
Stephanie Grünewald declares that she has no conflict of interest.
Rebecca Holman declares that she has no conflict of interest.
Johanna H. van der Lee declares that she has no conflict of interest.
Eileen P. Treacy declares that she has no conflict of interest.
Susan E. Waisbren declares that she has no conflict of interest.
Lindsey Welling declares that she has no conflict of interest.
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This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.
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Not required for this research study. This article does not contain any studies with human or animal subjects performed by any of the authors.
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Search strategies (DOCX 22 kb)
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Data retrieval (DOCX 52 kb)
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Raw data FSIQ scores classical galactosemia patients (PDF 53 kb)
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Welling, L. et al. (2017). Systematic Review and Meta-analysis of Intelligence Quotient in Early-Treated Individuals with Classical Galactosemia. In: Morava, E., Baumgartner, M., Patterson, M., Rahman, S., Zschocke, J., Peters, V. (eds) JIMD Reports, Volume 37. JIMD Reports, vol 37. Springer, Berlin, Heidelberg. https://doi.org/10.1007/8904_2017_22
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DOI: https://doi.org/10.1007/8904_2017_22
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