Genetic and environmental influences on the cognitive outcomes of children with fragile X syndrome.
OBJECTIVE
To measure the genetic and environmental factors influencing the cognitive outcomes in children with fragile X, a common genetic disorder causing cognitive impairments.


METHODS
In-home evaluations were conducted on 120 children (80 boys and 40 girls) with the fragile X full mutation and their unaffected siblings.


RESULTS
Multiple regression analyses show that the cognitive outcomes for girls with fragile X are most strongly predicted by the mean IQ of their parents, with a small proportion of the variance accounted for by the quality of their home environment. FMR1 protein (FMRP) was associated with girls' levels of distractibility. Mean parental IQ was associated only with boys' Performance IQs, while FMRP was associated with boys' Full Scale IQs. The quality of boys' home environments accounted for more of the variance in their cognitive outcomes than it did for affected girls.


CONCLUSIONS
Both biological/genetic factors and environmental factors are significant predictors of IQ in children with fragile X syndrome; however, the influence of specific factors differs between girls and boys. These findings lay the foundation for further investigation into biological and environmental interventions.
Dyer-Friedman
Jennifer
J
Department of Psychiatry, Stanford University School of Medicine, CA 94305-5719, USA. jennydf@stanford.edu
Glaser
Bronwyn
B
Hessl
David
D
Johnston
Cindy
C
Huffman
Lynne C
LC
Taylor
Annette
A
Wisbeck
Jacob
J
Reiss
Allan L
AL
D002648:Child; D003072:Cognition Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology; D004777:Environment; D005260:Female; D005600:Fragile X Syndrome / Q000150:complications / Q000453:epidemiology / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests