Fragile X syndrome in females with autism

A Multimethod Analysis of Pragmatic Skills in Children and Adolescents With Fragile X Syndrome, Autism Spectrum Disorder, and Down Syndrome

PURPOSE

Pragmatic language skills are often impaired above and beyond general language delays in individuals with neurodevelopmental disabilities. This study used a multimethod approach to language sample analysis to characterize syndrome- and sex-specific profiles across different neurodevelopmental disabilities and to examine the congruency of 2 analysis techniques.

METHOD

Pragmatic skills of young males and females with fragile X syndrome with autism spectrum disorder (FXS-ASD, n = 61) and without autism spectrum disorder (FXS-O, n = 40), Down syndrome (DS, n = 42), and typical development (TD, n = 37) and males with idiopathic autism spectrum disorder only (ASD-O, n = 29) were compared using variables obtained from a detailed hand-coding system contrasted with similar variables obtained automatically from the language analysis program Systematic Analysis of Language Transcripts (SALT).

RESULTS

Noncontingent language and perseveration were characteristic of the pragmatic profiles of boys and girls with FXS-ASD and boys with ASD-O. Boys with ASD-O also initiated turns less often and were more nonresponsive than other groups, and girls with FXS-ASD were more nonresponsive than their male counterparts. Hand-coding and SALT methods were largely convergent with some exceptions.

CONCLUSION

Results suggest both similarities and differences in the pragmatic profiles observed across different neurodevelopmental disabilities, including idiopathic and FXS-associated cases of ASD, as well as an important sex difference in FXS-ASD. These findings and congruency between the 2 language sample analysis techniques together have important implications for assessment and intervention efforts.

Signaling of noncomprehension in communication breakdowns in fragile X syndrome, Down syndrome, and autism spectrum disorder

The ability to indicate a failure to understand a message is a critical pragmatic (social) language skill for managing communication breakdowns and supporting successful communicative exchanges. The current study examined the ability to signal noncomprehension across different types of confusing message conditions in children and adolescents with fragile X syndrome (FXS), Down syndrome (DS), autism spectrum disorder (ASD), and typical development (TD). Controlling for nonverbal mental age and receptive vocabulary skills, youth with comorbid FXS and ASD and those with DS were less likely than TD controls to signal noncomprehension of confusing messages. Youth with FXS without ASD and those with idiopathic ASD did not differ from controls. No sex differences were detected in any group. Findings contribute to current knowledge of pragmatic profiles in different forms of genetically-based neurodevelopmental disorders associated with intellectual disability, and the role of sex in the expression of such profiles.

LEARNING OUTCOMES

Upon completion of this article, readers will have learned about: (1) the social-communicative profiles of youth with FXS, DS, and ASD, (2) the importance of signaling noncomprehension in response to a confusing message, and (3) the similarities and differences in noncomprehension signaling in youth with FXS (with and without ASD), DS, idiopathic ASD, and TD.

Do Anomalies of Handedness Exist in Children With Fragile-X Syndrome?

Hand preference and skill were assessed in 27 children with Fragile-X syndrome, 30 children with Down's Syndrome, and 29 normal developing children. Three separate and specific anomalies of handedness that have been reported in other learning-disordered groups were examined: increased incidence of left-handedness; ambiguous or inconsistent handedness; and preference-skill discordance. The results revealed no difference between the subject groups in the distribution of left-handedness or ambiguous handedness. The main differences was the percentage of children who were discordant for hand preference and hand skill. In the Fragile-X group 37% preferred to use their right hand but demonstrated no overall difference in skilled performance between the hands. In contrast, only 13% of children with Down's Syndrome and 17% of normal controls showed this pattern of hand discordance. The results are discussed in the context of past research that has shown a similar dissociation of preference and skill in children with autism.

Towards a neurodevelopmental model of clinical case formulation

Rapid advances in molecular genetics and neuroimaging over the last 10 to 20 years have been a catalyst for research in neurobiology, developmental psychopathology, and translational neuroscience. Methods of study in psychiatry, previously described as "slow maturing," now are becoming sufficiently sophisticated to more effectively investigate the biology of higher mental processes. Despite these technologic advances, the recognition that psychiatric disorders are disorders of neurodevelopment, and the importance of case formulation to clinical practice, a neurodevelopmental model of case formulation has not yet been articulated. The goals of this article, which is organized as a clinical case conference, are to begin to articulate a neurodevelopmental model of case formulation, to illustrate its value, and finally to explore how clinical psychiatric practice might evolve in the future if this model were employed.

The influence of environmental and genetic factors on behavior problems and autistic symptoms in boys and girls with fragile X syndrome

OBJECTIVE

Fragile X syndrome, caused by mutations in a single gene of the X chromosome (FMR1), is associated with neurobehavioral characteristics including social deficits with peers, social withdrawal, gaze aversion, inattention, hyperactivity, anxiety, depression, and autistic behavior. However, there is considerable variability in the behavioral and psychiatric problems among children with this condition. The purpose of this study was to measure genetic and environmental factors influencing behavior problems and autistic symptoms in children with fragile X syndrome.

DESIGN

We conducted an in-home evaluation of 120 children (80 boys and 40 girls) with the fragile X full mutation and their unaffected siblings, including measurements of the FMR1 protein (FMRP), quality of the home environment, maternal and paternal psychopathology, effectiveness of educational and therapeutic services, and child behavior problems.

RESULTS

Results of multiple regression analyses showed that for boys with fragile X, effectiveness of educational and therapeutic services and parental psychological problems predicted internalizing and externalizing types of problems, while the quality of the home environment predicted autistic behavior. For girls with fragile X, the results emphasized significant effects of FMRP on behavior, in particular social withdrawal and anxious/depressed behavior.

CONCLUSIONS

These findings are among the first to link FMRP expression to behavior. They also emphasize the significance of home- and school-based environmental variables in the neurobehavioral phenotype and help to lay the foundation for studies designed to identify specific interventions for reducing problem behavior in children with fragile X syndrome.

Absence of the fragile X CGG trinucleotide repeat expansion in girls diagnosed with a pervasive developmental disorder

The purpose of this study was to determine the prevalence of the fragile X (FRAX) CGG trinucleotide expansion in a population of young girls (n = 45) diagnosed with pervasive developmental disorder (PDD). Their mean age was 43.7 months (range, 25 to 132 months). Diagnoses included autistic disorder (n = 20), PDD (n = 23), and Asperger's syndrome (n = 2). Molecular FRAX testing was performed on all patients by using the Southern gene blot technique. Genomic DNA was digested with both EcoRI and EagI, fractionated on agarose gel, and blotted and probed with the radiolabeled StB12.3 FMR-1 probe. None of the subjects were found to have an expansion of CGG in either the 2.8 kb or 5.2 kb fragments. A 95% CI, for the prevalence of the FRAX mutation in female subjects with PDD, has an upper bound of 2.9%. We conclude that the prevalence of FRAX positivity in girls with PDD is lower than previously reported. This raises the question of whether any association between FRAX and PDD in female subjects is specific to PDD or is related rather to the presence of mental retardation.

Evaluation of school children at high risk for fragile X syndrome utilizing buccal cell FMR-1 testing

We describe a pilot project utilizing saliva to identify the FMR-1 mutation in high-risk special education students from four public school districts in Colorado. The program included presentations to special education teachers regarding fragile X syndrome, parental consent for testing, completion of a behavior checklist by the teachers, identification of special education students at high risk for fragile X syndrome, subsequent brief examination of face and hands, collection of a saliva sample by either Gatorade swish or brushing of the inside of the cheek, and analysis for the FMR-1 mutation by PCR. Equivocal samples were studied by direct DNA testing using Southern blot analysis, and abnormal results were confirmed by a blood analysis for the FMR-1 mutation. Mutant individuals received genetic counseling and medical and educational assessments to optimize treatment and intervention. This pilot project was met with enthusiasm by the schools. Of the first 439 students evaluated, 68% were male with an average age of 7.75 years; 13% were mentally retarded or autistic. Most students referred for the evaluation were learning disabled (51%) and/or had an Attention Deficit Hyperactivity Disorder (ADHD) (35%). The overall prevalence of the FMR-1 mutation was 5 of 439 or 1.1%. This relatively low yield is probably due to the high number of non-retarded but learning disabled students tested. Of the mentally retarded patients tested, 3.5% were positive for the FMR-1 mutation; however, of the non-retarded or learning disabled patients, only 0.79% were FMR-1 positive.(ABSTRACT TRUNCATED AT 250 WORDS)

Autism and related behaviours

Childhood autism is conceptualized as a behavioural syndrome with several different aetiologies. Its prevalence is estimated at about one in every thousand children born. The male:female ratio is considerably higher than in the general population, but possibly not as high as 3-4:1 (as has been suggested for almost 50 years in the literature). A number of specific medical conditions are associated with autism and a comprehensive medical work-up is required in all cases with pervasive autistic symptomatology. Genetic factors contribute to the development of autism in some cases. Recent neurobiological and psychological studies contribute to a concept of the autistic syndrome as but one of several different syndromes characterized by impaired empathy skills.

What is associated with the fragile X syndrome?

In addition to mental retardation (MR), fragile X[fra(X)] syndrome has been associated with a variety of other disorders. Despite earlier reports, it has been shown that MR fra(X) males are at no greater risk for autism than is any MR male. Therefore, studies in which fra(X) has been associated with behavioral, developmental, and psychopathological disabilities were examined to determine whether fra(X) individuals were at an increased risk for these dysfunctions as well. Psychiatric disorders among fra(X) individuals were found not to occur more frequently than in other individuals with cognitive deficits. It was also observed that hyperactivity and attention deficit disorder among MR fra(X) individuals do not occur more frequently than in other MR individuals. Pooled results from studies of cognitive profiles used to characterize fra(X) phenotypes also indicated that there are no consistent patterns in either males or females. Plausible explanations for a variable phenotype include allelic heterogeneity and pleitropy.

Prevalence of the fragile X anomaly amongst autistic twins and singletons

Early screening studies of autistic individuals suggested that up to one-quarter of cases were associated with the Fragile X anomaly. Recent studies find that the usual behavioural phenotype of the Fragile X anomaly is distinct from autism as usually defined, and that a variety of methodological factors contribute to the variability of the prevalence estimates. We report the prevalence of the Fragile X anomaly, using strict cytogenetic criteria, in a large sample of autistic individuals whose diagnosis was confirmed using a standardised diagnostic instrument. The anomaly was detected in 1.6% of tested autistic individuals from a combined sample of: autistic twins; clinic attenders; and, individuals from families multiplex for autism or related cognitive phenotypes. The anomaly was not detected in greater than 2.5% of any of the constituent samples and accounted for only a small proportion of the genetic influences amongst concordant twins and multiplex families. The anomaly was detected in 5% of the 40 tested autistic females, confirming reports that the prevalence of the anomaly is similar amongst autistic individuals of both sexes.

The fragile-X syndrome. On the way to a behavioural phenotype

The fragile-X syndrome accounts for up to 10% of individuals with mental handicap, and 50% of cases of X-linked mental retardation. Knowledge of the genetic basis of mental functioning, psychopathology, and neuropsychology is being furthered by this recently recognised condition. The disorder has considerable significance for psychiatrists, particularly, but by no means exclusively, those working in the field of mental handicap and with children. This review outlines the slow clarification of this complex and important behavioural phenotype and the implications of these advances for identification, diagnosis, genetic counselling and a wide range of management interventions.

Neuropsychological, psychiatric, and physical manifestations in 149 members from 18 fragile X families

One hundred forty-nine subjects from 18 families with fragile X [fra(X)] syndrome were evaluated for their neuropsychological, psychiatric, and physical characteristics. The 36 fra(X) males had intelligence quotients ranging from less than 20 to 61, which prevented the delineation of a reliable neuropsychological profile. Behaviour fitted DSM-III-R and ADI diagnostic criteria of autism in only 2 subjects, both with very low intelligence level (IQ less than 20). Of 36 heterozygotes (HZ), 22 had an IQ between 20 and 80 and 14 between 81 and 99. The neuropsychological profile of the latter was compared with IQ-age-environment-matched 14 normal females and 14 normal males. Significantly poorer results in HZ were found on immediate digit memory and on Raven's progressive matrices (a visuo-spatial test of logical capabilities). The latter result, in conjunction with those results on the Bender visual-motor gestalt test and on some WAIS subtests, suggests a frequent deficit in spatial capabilities in such subjects. Such results tended to be confirmed by the profiles of the 22 HZ with IQ 20-80. No psychiatric abnormalities were found in HZ, except in one subject with IQ less than 20 which fitted DSM-III-R and ADI criteria for autism. Typical physical manifestations, especially cranio-facial, were more frequently present in the HZ group with lower IQ. Subnormal IQ was probably the most reliable abnormality for the detection of HZ in 49 females at 50% and 25% risk of heterozygosity.

Prevalence of fra(X) and other specific diagnoses in autistic individuals in a Danish county

In a Danish county (the island of Funen) cytogenetic screening for fragile X [fra(X)] of 32 autistic individuals aged 0-23 years showed a prevalence of 2/20 among boys and 0/12 among girls. In both cases additional fra(X) positive relatives were found. In 3 patients other chromosome aberrations were demonstrated and in one female Rett syndrome was diagnosed, initially suspected from observations of her behavior on videotapes. The presence of an underlying cause of autism in 6/32, of the patient group encourages an active search for a specific diagnosis among autistic males and females. Future screening of autistic individuals should include 1) fra(X) search also in females, 2) search for other chromosomal disorders, and 3) observation of behavior, in order to diagnose, i.e., Rett syndrome.