Increased prevalence of seizures in boys who were probands with the FMR1 premutation and co-morbid autism spectrum disorder.

Seizures are a common co-occurring condition in those with fragile X syndrome (FXS), and in those with idiopathic autism spectrum disorder (ASD). Seizures are also associated with ASD in those with FXS. However, little is known about the rate of seizures and how commonly these problems co-occur with ASD in boys with the FMR1 premutation. We, therefore, determined the prevalence of seizures and ASD in boys with the FMR1 premutation compared with their sibling counterparts and population prevalence estimates. Fifty premutation boys who presented as clinical probands (N = 25), or non-probands (identified by cascade testing after the proband was found) (N = 25), and 32 non-carrier controls were enrolled. History of seizures was documented and ASD was diagnosed by standardized measures followed by a team consensus of ASD diagnosis. Seizures (28%) and ASD (68%) were more prevalent in probands compared with non-probands (0 and 28%), controls (0 and 0%), and population estimates (1 and 1.7%). Seizures occurred more frequently in those with the premutation and co-morbid ASD particularly in probands compared with those with the premutation alone (25 vs. 3.85%, p = 0.045). Although cognitive and adaptive functioning in non-probands were similar to controls, non-probands were more likely to meet the diagnosis of ASD than controls (28 vs. 0%, p < 0.0001). In conclusion, seizures were relatively more common in premutation carriers who presented clinically as probands of the family and seizures were commonly associated with ASD in these boys. Therefore, boys with the premutation, particularly if they are probands should be assessed carefully for both ASD and seizures.

Autism profiles of males with fragile X syndrome.

Autism, which is common in individuals with fragile X syndrome, is often difficult to diagnose. We compared the diagnostic classifications of two measures for autism diagnosis, the ADOS and the ADI-R, in addition to the DSM-IV-TR in 63 males with this syndrome. Overall, 30% of the subjects met criteria for autistic disorder and 30% met criteria for PDD-NOS. The classifications on the ADOS and DSM-IV-TR were most similar, whereas the ADI-R classified subjects as autistic much more frequently. We further investigated the relationship of both FMRP and FMRI mRNA to symptoms of autism in this cohort and found no significant relationship between the measures of autism and molecular features, including FMRP, FMRI mRNA, and CGG repeat number.

Penetrance of the fragile X-associated tremor/ataxia syndrome in a premutation carrier population.

CONTEXT: Premutation expansions (55-200 CGG repeats) of the fragile X mental retardation 1 (FMR1) gene are frequent in the general population, with estimated prevalences of 1 per 259 females and 1 per 813 males. Several articles have recently described the presence of late-onset neurological symptoms in male carriers of premutation (FMR1) alleles. The main clinical features described in this newly identified syndrome are cerebellar ataxia and intention tremor. Additional documented symptoms include short-term memory loss, executive functional deficits, cognitive decline, parkinsonism, peripheral neuropathy, lower-limb proximal muscle weakness, and autonomic dysfunction. OBJECTIVE: To study the penetrance of the fragile X-associated tremor/ataxia syndrome (FXTAS) among premutation carriers. DESIGN, SETTING, AND PARTICIPANTS: Family-based study of 192 individuals (premutation carriers and controls) whose families belong to the Northern or Southern California Fragile X Associations. Data were collected (March 2002-April 2003) through a survey and a standardized neurological examination, which was videotaped and subsequently scored in a blinded fashion. MAIN OUTCOME MEASURES: Penetrance of intention tremor and ataxia among adult carriers (aged > or =50 years) of premutation expansions of the FMR1 gene. RESULTS: Data from the survey of 192 individuals demonstrated an age-related penetrance of the combination of reported intention tremor and gait ataxia in male carriers (17%, 38%, 47%, and 75% [lower-bound estimates] for participants aged 50-59, 60-69, 70-79, and > or =80 years, respectively). The male carrier group had an age-adjusted 13-fold increased risk (95% confidence interval, 3.9-25.4; P =.003) of combined intention tremor and gait ataxia when compared with male controls. The clinical examination data from 93 individuals demonstrated that male carriers experienced more difficulties on each of 3 standardized neurological rating scales compared with controls (P<.05). Female carrier scores were also higher than those of female controls (P<.05) on 2 of the 3 neurological rating scales, but no participant was identified with probable or definite FXTAS. CONCLUSIONS: The study demonstrates that older male carriers of premutation alleles of the FMR1 gene are at high risk of developing FXTAS. Since male premutation carriers are relatively common in the general population, older men with ataxia and intention tremor should be screened for the FMR1 mutation, especially if these signs are accompanied by parkinsonism, autonomic dysfunction, or cognitive decline, regardless of family history.

Influence of stimulants on electrodermal studies in Fragile X syndrome.

Attention Deficit Hyperactivity Disorder (ADHD) is seen in the majority of children with Fragile X Syndrome (FraX). Previous work has documented an enhanced sweat response to stimuli in children with FraX compared to controls utilizing electrodermal response (EDR) measures. The present study assesses the EDRs both on and off stimulants in 19 children with ADHD and FraX compared to 17 age- and IQ-matched control patients with ADHD and developmental delays. Although the baseline EDRs were comparable between FraX patients and controls, the patients with FraX had a significant decrease in EDR amplitude and number of peaks when treated with stimulants compared to controls. This suggests that patients with FraX are more responsive to the enhancement of inhibitory systems that occur with stimulant use for ADHD. The use of a quantifiable measure, such as EDR, is recommended in future studies of treatment efficacy.