ARTICLES
Genetic and Environmental Influences on the Cognitive Outcomes of Children With Fragile X Syndrome

https://doi.org/10.1097/00004583-200203000-00002Get rights and content

ABSTRACT

Objectives

To measure the genetic and environmental factors influencing the cognitive outcomes in children with fragile X, a common genetic disorder causing cognitive impairments.

Method

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.

Section snippets

Subjects

Families were recruited from an existing fragile X registry, through advertisements in fragile X association newsletters and web sites, and through referrals from clinicians and families. To determine eligibility, families completed a telephone-screening interview covering basic demographic information, family history of fragile X, and their children's developmental histories. Subjects were excluded because of other known medical problems or signs of current illness. Confirmatory DNA testing

RESULTS

There were no significant differences between unaffected female siblings and unaffected male siblings on any of the IQ scales. Therefore, the unaffected male and female siblings were combined into one comparison group. A multivariate analysis of variance revealed an overall group effect for the three IQ scales: FSIQ (F3 = 324.35, p < .000), PIQ (F3 = 293.26, p < .000), and VIQ (F3 = 254.52, p < .000). Follow-up Tukey honestly significant difference pairwise tests revealed significant group

DISCUSSION

This study aimed to describe the cognitive profiles of girls and boys with fragile X and to investigate the potential contributions of both biological/genetic and environmental factors to the cognitive outcomes of these children. As predicted, girls with fragile X had somewhat higher cognitive abilities than did boys with fragile X and had relative strengths in verbal domains. Importantly, we also observed that both biological/genetic factors and the quality of the home environment contribute

REFERENCES (25)

  • R Willemsen et al.

    Rapid antibody test for fragile X syndrome

    Lancet

    (1995)
  • TL Baumgardner et al.

    Specification of the neurobehavioral phenotype in males with fragile X syndrome

    Pediatrics

    (1995)
  • Bennetto L, Pennington BF (1996), The neuropsychology of fragile X syndrome. In: Fragile X Syndrome: Diagnosis,...
  • ML Boccia et al.

    Behavior and autonomic nervous system function assessed via heart period measures: the case of hyperarousal in boys with fragile X syndrome

    Behav Res Methods Instrum Comput

    (2000)
  • RH Bradley

    Children's home environments, health, behavior, and intervention efforts: a review using the HOME inventory as a marker measure

    Genet Soc Gen Psychol Monogr

    (1993)
  • BM Caldwell et al.

    Home Observation for Measurement of the Environment

    (1984)
  • IL Cohen

    A theoretical analysis of the role of hyperarousal in the learning and behavior of fragile X males

    Mental Retardation Dev Disabilities Res Rev

    (1995)
  • JC DeFries et al.

    Familial resemblance for specific cognitive abilities

    Behav Genet

    (1979)
  • Dyer-Friedman J, Hessl D, Glaser B, Kosaraju A, Reiss AL (2001), The Special Curriculum Opportunity Rating Scale...
  • E Dykens et al.

    Trajectories and profiles of adaptive behavior in males with fragile X syndrome: multicenter studies

    J Autism Dev Disord

    (1996)
  • GS Fisch et al.

    Longitudinal study of cognitive abilities and adaptive behavior levels in fragile X males: a prospective multicenter analysis

    Am J Med Genet

    (1996)
  • LS Freund et al.

    A neurocognitive phenotype of young males and females with fragile X

    Neuropsychiatry Genet

    (1996)
  • Cited by (0)

    This work was supported by NIH grants MHO1142 and MH50047. Further support was received from the Packard Foundation and the Lynda and Scott Canel Fund for Fragile X Research. The authors thank Christine Blasey for statistical consultation.

    View full text