Longitudinal IQ changes in fragile X males

Hagerman, Randi J.; Schreiner, Rebecca; Kemper, Melinda B.; Wittenberger, Michael D.; Zahn, Betsy; Habicht, Kristin

doi:10.1002/ajmg.1320330422

Cited by 87 publications

(63 citation statements)

References 12 publications

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“…A more appropriate conclusion is that adults with SMS do not show a decline in cognitive abilities, at least not those aged up to 50 years, and they seem to follow the same trend as the general population in showing a slight increase in IQ scores from WISC to WAIS re-testing. This is in contrast to the picture of a decline in IQ scores over time in other genetic disorders like fragile X syndrome (Hagerman et al 1989) and Down syndrome (Dunst 1988).…”

Section: Discussioncontrasting

confidence: 70%

Abilities and attainment in Smith‐Magenis syndrome

Udwin

Horn

2001

Develop Med Child Neuro

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This study reports on cognitive abilities and attainment in 29 children and 21 adults with Smith-Magenis syndrome. There were 13 boys and 16 girls aged 6 to 16 years, and nine men and 12 women aged 16 to 52 years. All had mild to severe learning disabilities* with no differences overall between verbal and performance skills, but with a particular profile of cognitive strengths and weaknesses. Levels of attainment and of adaptive behaviour were strikingly low, and the group of adults emerged as much more dependent on carers than might have been expected from their general level of intellectual functioning. Reasons for this discrepancy are explored in terms of the severe behavioural difficulties characteristic of the syndrome.

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Section: Discussioncontrasting

confidence: 70%

Abilities and attainment in Smith‐Magenis syndrome

Udwin

Horn

2001

Develop Med Child Neuro

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“…Most FRAXA males are moderately to severely mentally retarded, and demonstrate visual-spatial weaknesses and verbal/comprehension strengths . Furthermore, males with the FRAXA full mutation have been shown to experience a decline or plateau in IQ which occurs in early to late childhood [Hagerman et al, 1989;Dykens et al, 1993]. The IQ scores of the two FRAXE subjects presented in this report did not decline with age (Table I).…”

Section: Comparison To Other Fraxe and Fraxa Malesmentioning

confidence: 54%

Cognitive, behavioral, and neuroanatomical assessment of two unrelated male children expressingFRAXE

et al. 1997

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Standardized cognitive, behavioral, and neuroanatomical data are presented on 2 unrelated boys with the FRAXE (FMR2) GCC expansion mutation. In the context of normal IQ, both boys had a history of developmental delay, including significant problems with communication, attention, and overactivity. Additionally, one child was diagnosed with autistic disorder. Data from these 2 cases are compared to analogous information from previous reports about individuals with the FRAXE or FRAXA (FMR1) mutation. These comparisons support the idea that FRAXE is associated with nonspecific developmental delay and possibly high-functioning autism.

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“…In a subsequent prospective study of a different group of 13 girls with FXS, significant IQ decreases were again observed in eight subjects (Fisch et al 1996). Yet, a review of these studies suggests that not all individuals with FXS show declining IQs over time (Hagerman et al 1989;Wright-Talamante et al 1996). Based on a retrospective chart review of 50 males and females with FXS who had repeated standardized IQ testing separated by 7 months to 13 years, intellectual development appeared to depend, in part, on genotypic features such as the presence of incomplete methylation (Wright-Talamante et al 1996).…”

mentioning

confidence: 99%

“…Accordingly, these investigators hypothesized that a subgroup of individuals with higher levels of FMRP may be less vulnerable to IQ decline. It has also been argued that declining IQ in individuals with FXS might also be explained by inherent properties of cognitive tests, which for older children, may place greater emphasis on skills that are known to be specific weaknesses in this disorder (Hagerman et al 1989). As Hay (1994) has also pointed out, interpretation of standardized IQ data in individuals with FXS is extremely problematic because investigators have combined data from different tests, different sources and from different age-groups.…”

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confidence: 99%

Longitudinal Changes in Intellectual Development in Children with Fragile X Syndrome

Hall

Burns

Lightbody

et al. 2008

J Abnorm Child Psychol

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Structural equation modeling (SEM) was used to examine the development of intellectual functioning in 145 school-age pairs of siblings. Each pair included one child with Fragile X syndrome (FXS) and one unaffected sibling. All pairs of children were evaluated on the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) at time 1 and 80 pairs of children received a second evaluation at time 2 approximately 4 years later. Compared to their unaffected siblings, children with FXS obtained significantly lower percentage correct scores on all subtests of the WISC at both time points. During the time between the first and second assessments, the annual rate of intellectual development was approximately 2.2 times faster in the unaffected children compared to the children with FXS. Levels of the fragile X mental retardation protein (FMRP) were highly associated with intellectual ability scores of the children with FXS at both time points (r=0.55 and 0.64 respectively). However, when gender, age, and the time between assessments were included as covariates in the structural equation model, FMRP accounted for only 5% of the variance in intellectual ability scores at time 1 and 13% of the variance at time 2. The results of this study suggest that slower learning contributes to the low and declining standardized IQ scores observed in children with FXS. KeywordsFragile X syndrome; Structural equation modeling; Intellectual functioning; IQ; FMRP Fragile X syndrome occurs in approximately 1 in every 4,000 live births and is the most common inherited form of cognitive and behavioral disability. In 1991, Verkerk and colleagues reported that a single gene on the X chromosome (locus Xq27.3), FMR1, was associated with the symptoms of FXS (Verkerk et al. 1991). Subsequent research revealed that persons with FXS had increased numbers of triplet (CGG) repeats within FMR1. In normal alleles, the CGG repeats vary from 6 to 50, whereas expansions of ~50-200 repeats are associated with the "premutation" form of the gene seen in carrier females and males. The probability of having a child with the full mutation increases as the length of the mothers' CGG repeat length increases-a phenomenon known as genetic anticipation. Larger expansions (200 to thousands) of CGG repeats are considered "full mutations" and are typically associated with excessive methylation of cytosines in the FMR1 promoter. This hallss@stanford.edu. HHS Public AccessAuthor manuscript J Abnorm Child Psychol. Author manuscript; available in PMC 2016 April 04. Author Manuscript Author ManuscriptAuthor ManuscriptAuthor Manuscript modification extinguishes transcription of the FMR1 gene into mRNA, thus stopping translation of the fragile X mental retardation protein (FMRP). FMRP plays an important role in the development of synaptic function, maturation, and plasticity during development, and possibly, on an ongoing basis throughout adult life as well (Reiss et al. 1995).Investigators have reported that individuals with FXS experience weaknesses in executi...

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Longitudinal IQ changes in fragile X males

Cited by 87 publications

References 12 publications

Abilities and attainment in Smith‐Magenis syndrome

Abilities and attainment in Smith‐Magenis syndrome

Cognitive, behavioral, and neuroanatomical assessment of two unrelated male children expressingFRAXE

Longitudinal Changes in Intellectual Development in Children with Fragile X Syndrome

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