Autism spectrum disorders in children with a history of infantile spasms: a population-based study

The objective of this article is to describe autistic spectrum disorders in children diagnosed with infantile spasms in the first year of life. The source of data was the records of all 3 pediatric departments in Iceland. Twenty children born between 1981 and 1998 who had infantile spasms were invited to participate. When appropriate, the parents of these children were asked to complete the Social Communication Questionnaire. Children scoring 10 points or higher on the questionnaire were selected for further examination using the Autism Diagnostic Interview- Revised and either the Autism Diagnostic Observation Schedule or the Childhood Autism Rating Scale. All participants were given appropriate cognitive tests or measures of adaptive behavior. The parents of 17 children (10 boys, 7 girls) agreed to participate in the study. Age at assessment ranged from 5 to 19 years with a mean age of 11 years and 6 months. Fourteen children had at least one neurodevelopmental disorder. Six (6/17), or 35.3%, were diagnosed with autism spectrum disorder (3 boys, 3 girls), five of these had a history of symptomatic infantile spasms, and four were profoundly mentally retarded (IQ/DQ<20). If the diagnosis of autism spectrum disorder was restricted to children with a developmental age of 24 months or more (3 cases), the prevalence was 17.6%. The estimates found in this study exceed the estimated prevalence of autism spectrum disorder in the general population.     

Autism spectrum disorders: sex differences in autistic behaviour domains and coexisting psychopathology

The purpose of the present study was to examine possible differences between high-functioning males and females with autism spectrum disorder (ASD) regarding the core symptoms of autism and coexisting psychopathology. A total of 23 females and 23 males matched for age, IQ, and ASD diagnoses were recruited(mean age 11y 9mo [SD 4y 5mo], range 5y-20y 2mo) with an IQ above the range of learning disability (mean IQ 88.8 [SD 18.5], range 70-128). They were compared using the Autism Diagnostic Interview-Revised, the Autism Diagnostic Observation Schedule, and the Child Behavior Checklist/4-18. We did not identify striking differences between males and females for the triad of autism core dysfunctions (deficits in reciprocal social interaction, communication, and repetitive, stereotyped behaviours) as assessed by expert ratings. However, with regard to several domains of coexisting psychopathology, parent reports revealed significantly more symptoms in females than males, particularly social problems (t=4.47, p<0.01, d=1.20), attention problems (t=3.39, p<0.01, d=0.80), and thought problems (t=3.24, p<0.01, d=0.84). These results are discussed with possible interpreting bias by parents who may expect more socially desired behaviour from daughters than from sons. The severity of social and attention problems in high-functioning females with autism emphasizes the need for thorough assessments and interventions in these domains. Future research should compare the cognitive phenotype of autism between sexes.     

Gait function in newly diagnosed children with autism: Cerebellar and basal ganglia related motor disorder

We investigated gait in newly diagnosed children with autism. From our previous study with 6- to 14-year-olds, we hypothesized that motor symptoms indicative of basal ganglia and cerebellar dysfunction would appear across the developmental trajectory of autism. Two groups were recruited: children with autism (eight males, three females; mean age 5 y 10 mo [SD 9 mo]; range 4 y 4 mo-6 y 9 mo) and a comparison group of typically developing children (eight males, three females; mean age 5 y 9 mo [SD 1 y 1 mo]; range 4 y 3 mo-7 y 2 mo). The GAITRite Walkway was used to gather data from average gait and intra-walk measurements. Experienced physiotherapists analyzed gait qualitatively. Groups were matched according to age, height, weight, and IQ; although not statistically significant, IQ was lower in the group with autism. Spatiotemporal gait data for children with autism were compatible with findings from patients with cerebellar ataxia: specifically, greater difficulty walking along a straight line, and the coexistence of variable stride length and duration. Children with autism were also less coordinated and rated as more variable and inconsistent (i.e. reduced smoothness) relative to the comparison group. Postural abnormalities in the head and trunk suggest additional involvement of the fronto-striatal basal ganglia region. Abnormal gait features are stable across key developmental periods and are, therefore, promising for use in clinical screening for autism.     

Autism and phenylketonuria

Phenylketonuria (PKU) has been also reported in children with infantile autism (IA); however, the frequency of this association is variably reported. Patients with various forms of hyperphenylalaninemia (HPA) were evaluated applying two methods: the Autism Diagnostic Interview-Revised (ADI-R) and the Childhood Autism Rating Scale (CARS). A total of 243 patients were investigated, 97 with classical PKU, 62 identified by neonatal screening, and 35 late diagnosed. None out of 62 patients with classic PKU diagnosed early met criteria for autism. In the group of 35 patients diagnosed late, two boys (5.71%) ages 16 and 13 years fulfilled the diagnostic criteria for autism. The present study confirms that classical PKU is one of the causes of autism, but the prevalence seems to be very low.     

Pervasive developmental disorders in individuals with cerebral palsy

The aim of the present study was to describe the prevalence and associated factors of pervasive developmental disorders (PDD), including autistic disorder and PDD not otherwise specified (NOS), in a clinical sample of 126 children and adolescents (75 males, 51 females; age range 4–18y, mean 8y 8mo, SD 3y 8mo) with tetraplegic, hemiplegic, diplegic, dyskinetic, or mixed types of cerebral palsy (CP); 28% could not crawl or walk even with support, 29% could move with support, and 43% walked independently. Participants were examined for PDD in two stages. In the first stage, probable participants were determined by direct observation, Autism Behavior Checklist score, and medical reports. In the second stage, those with 'probable' symptoms underwent psychiatric examination and their autistic symptoms were scored on the Childhood Autism Rating Scale. The final diagnosis of autistic disorder or PDD-NOS was given according to DSM-IV criteria. Fourteen (11%) and five (4%) of the participants met the criteria for autistic disorder and PDD-NOS respectively. Children with CP and PDD differed from those without PDD in terms of type of CP ( p =0.02), presence of epilepsy ( p <0.001), intellectual level ( p <0.001), and level of speech ( p <0.001). PDD was more common in children with tetraplegic, mixed, and hemiplegic CP, and in children with epilepsy, learning disability, * and low level of speech. The findings corroborate the notion that CP is a complex disorder, often associated with additional impairments. PDD is not rare in CP and should be considered in patients with comorbid conditions such as epilepsy, learning disability, and language delay and in the presence of tetraplegic, mixed, and hemiplegic CP types.     

Autism and diagnostic substitution: evidence from a study of adults with a history of developmental language disorder

Rates of diagnosis of autism have risen since 1980, raising the question of whether some children who previously had other diagnoses are now being diagnosed with autism. We applied contemporary diagnostic criteria for autism to adults with a history of developmental language disorder, to discover whether diagnostic substitution has taken place. A total of 38 adults (aged 15–31y; 31 males, seven females) who had participated in studies of developmental language disorder during childhood were given the Autism Diagnostic Observation Schedule - Generic. Their parents completed the Autism Diagnostic Interview - Revised, which relies largely on symptoms present at age 4 to 5 years to diagnose autism. Eight individuals met criteria for autism on both instruments, and a further four met criteria for milder forms of autistic spectrum disorder. Most individuals with autism had been identified with pragmatic impairments in childhood. Some children who would nowadays be diagnosed unambiguously with autistic disorder had been diagnosed with developmental language disorder in the past. This finding has implications for our understanding of the epidemiology of autism.     

The physical status of children with autism in China

The height, weight and BMI of children with autism was investigated and analyzed to find the physical status of children with autism in China. Three hundred and eighty boys and 49 girls diagnosed with autistic disorder participated. Their parents were interviewed with a questionnaire about general information, and children were evaluated with Childhood Autism Rating Scale, and height and weight were measured. Children with autism had high level height, weight and BMI; the rate of height >or=P(75) was less in 6-11 years old group than that in 2-5 years old group in boys and all children. The prevalence of at-risk-for or being overweight was 31.8% and 17.0% in 2-5 years old group, were 37.9% and 21.8% in 6-11 years old group. At-risk-for-overweight/overweight of children with autism had no relationship with their core symptoms, the older age was the only predictor for lower height and at-risk-for-overweight. Prevalence of at-risk-for-overweight and overweight in children with autism was high. Children's height level decreased, and being at-risk-for-overweight increased with age.     

Electrophysiological signs of supplementary-motor-area deficits in high-functioning autism but not Asperger syndrome: an examination of internally cued movement-related potentials

Aims  Motor dysfunction is common to both autism and Asperger syndrome, but the underlying neurophysiological impairments are unclear. Neurophysiological examinations of motor dysfunction can provide information about likely sites of functional impairment and can contribute to the debate about whether autism and Asperger syndrome are variants of the same disorder or fundamentally distinct neurodevelopmental conditions. We investigated the neurophysiology of internally determined motor activity in autism and Asperger syndrome via examination of movement-related potentials (MRPs).
Method  We used electroencephalography to investigate MRPs, via an internally cued movement paradigm, in the following three groups: (1) individuals with high-functioning autism (14 males, one female; mean age 13y 1mo, SD 4y 2mo, range 7y 8mo to 20y 9mo; mean Full-scale IQ 93.40, SD 20.72); (2) individuals with Asperger syndrome (10 males, two females; mean age 13y 7mo, SD 3y 9mo, range 8y 11mo to 20y 4mo; mean Full-scale IQ 103.25, SD 19.37), and (3) a healthy control group (13 males, seven females; mean age 14y 0mo, SD 3y 11mo; range 8y 4mo to 21y 0mo; mean Full-scale IQ 114.25, SD 11.29).
Results  Abnormal MRPs can reflect disruption of motor-related neural networks involving the basal ganglia, thalamus, and supplementary motor area. There was evidence for abnormal MRPs in autism (e.g. increased post-movement cortical activity, abnormal peak time) but not in Asperger syndrome.
Interpretation  The results support basal ganglia, thalamus, and supplementary motor area involvement as a likely source of motor dysfunction in autism, and provide further evidence for the neurobiological separateness of autism and Asperger syndrome.     

Impairment in movement skills of children with autistic spectrum disorders

Aim  We undertook this study to explore the degree of impairment in movement skills in children with autistic spectrum disorders (ASD) and a wide IQ range.
Method  Movement skills were measured using the Movement Assessment Battery for Children (M-ABC) in a large, well defined, population-derived group of children ( n =101: 89 males,12 females; mean age 11y 4mo, SD 10mo; range 10y–14y 3mo) with childhood autism and broader ASD and a wide range of IQ scores. Additionally, we tested whether a parent-completed questionnaire, the Developmental Coordination Disorder Questionnaire (DCDQ), was useful in identifying children who met criteria for movement impairments after assessment ( n =97 with complete M-ABCs and DCDQs).
Results  Of the children with ASD, 79% had definite movement impairments on the M-ABC; a further 10% had borderline problems. Children with childhood autism were more impaired than children with broader ASD, and children with an IQ less than 70 were more impaired than those with IQ more than 70. This is consistent with the view that movement impairments may arise from a more severe neurological impairment that also contributes to intellectual disability and more severe autism. Movement impairment was not associated with everyday adaptive behaviour once the effect of IQ was controlled for. The DCDQ performed moderately well as a screen for possible motor difficulties.
Interpretation  Movement impairments are common in children with ASD. Systematic assessment of movement abilities should be considered a routine investigation.     

Autism spectrum conditions in individuals with Möbius sequence,CHARGE syndrome and oculo-auriculo-vertebral spectrum: Diagnostic aspects

As part of multidisciplinary surveys of three Behavioural Phenotype Conditions (BPCs); Möbius sequence (Möbius), CHARGE syndrome (CHARGE) and oculo-auriculo-vertebral spectrum (OAV), autism spectrum conditions (ASCs) was diagnosed in 45%, 68% and 42% of the individuals, respectively. Diagnostic difficulties due to additional dysfunctions such as mental retardation (MR), impaired vision, reduced hearing and cranial nerve dysfunction, were experienced in all three BPC groups. The applicability of current autism diagnostic instruments, such as the Autism Diagnostic Interview-Revised (ADI-R), the Childhood Autism Rating Scale (CARS) and the Autistic Behaviour Checklist (ABC), in individuals with ASCs and Möbius/CHARGE/OAV was analysed. Use of an extensive battery of diagnostic instruments, including both observational schedules and parent interviews, and, if possible, independent judgements from two clinicians, is essential in the diagnostics of ASCs in these individuals. Further, in individuals who are deaf and blind the applicability of current autism diagnostic instruments is highly questionable.     

Movement-related potentials in high-functioning autism and Asperger's disorder

Autism and Asperger's disorder (AD) are neurodevelopmental conditions that affect cognitive and social-communicative function. Using a movement-related potential (MRP) paradigm, we investigated the clinical and neurobiological issue of 'disorder separateness' versus 'disorder variance' in autism and AD. This paradigm has been used to assess basal ganglia/supplementary motor functioning in Parkinson's disease. Three groups (high functioning autism [HFA]: 16 males, 1 female; mean age 12y 5mo [SD 4y 4mo]; AD: 11 males, 2 females; mean age 13y 5mo [SD 3y 8mo]; comparison group: 13 males, 8 females; mean age 13y 10mo [SD 3y 11mo]) completed a cued motor task during electroencephalogram recording of MRPs. The HFA group showed reduced peak amplitude at Cz, indicating less activity over the supplementary motor area during movement preparation. Although an overall significant between-group effect was found for early slope and peak amplitude, sub-analysis revealed that the group with AD did not differ significantly from either group. However, it is suggested that autism and AD may be dissociated on the basis of brain-behaviour correlations of IQ with specific neurobiological measures. The overlap between MRP traces for autism and Parkinson's disease suggests that the neurobiological wiring of motor functioning in autism may bypass the supplementary motor area/primary motor cortex pathway.     

Can Asperger syndrome be diagnosed at 26 months old? A genetic high-risk single-case study

Asperger syndrome, a heritable condition entailing empathy deficits together with unusually narrow interests in individuals of normal or even above-average intelligence, was recognized only recently. Here we report the first-ever prospective study of a child born to two adults with a formal diagnosis of Asperger syndrome. The child's parents are both scientists (a mathematician and a chemist). The aim of study 1 was to test if the child also developed Asperger syndrome, given the heritability of the condition, and if Asperger syndrome can be detected at 26 months. At 18 months, the child was given the Checklist for Autism in Toddlers, and at 26 months, she was assessed diagnostically for autism spectrum conditions using the Autism Diagnostic Interview-Revised and the Autism Diagnostic Observational Scale. The child failed the Checklist for Autism in Toddlers at 18 months and met the criteria for Asperger syndrome at 26 months. This single case is consistent with the hypersystemizing, assortative mating theory of autism. This theory requires further testing with large samples. This study also demonstrates that Asperger syndrome can be diagnosed by age 26 months. The aim of study 2 was to test if dyadic eye contact in infancy is intact in a child later diagnosed with Asperger syndrome. The same child's eye contact was measured at three time points (3, 6, and 9 months) over her first year of life and compared with that of age-matched controls. Although the child had low rates of eye contact at 6 months, it was within the normal range at all three points in the first year of life. We conclude that low levels of eye contact are not predictive of later development of Asperger syndrome.     

Developing a schedule to identify social communication difficulties and autism spectrum disorder in young children with visual impairment

Available observational tools used in the identification of social communication difficulties and diagnosis of autism spectrum disorder (ASD) rely partly on visual behaviours and therefore may not be valid in children with visual impairment. A pilot observational instrument, the Visual Impairment and Social Communication Schedule (VISS), was developed to aid in identifying social communication difficulties and ASD in young children with visual impairment affected by congenital disorders of the peripheral visual system (disorders of the globe, retina, and anterior optic nerve). The VISS was administered to 23 consecutive children (age range 1 y 9 mo-6 y 11 mo, mean 4 y 1 mo [SD 1.6]; 12 males, 11 females) with visual impairment (nine with severe and 14 with profound visual impairment). Item analysis was carried out by fit of the items to the Rasch model. Validity of the VISS was explored by comparison with the Childhood Autism Rating Scale (CARS) score, and the clinical ASD diagnosis (n=9). Correlation between the VISS and CARS total scores was highly significant (Spearman's rho=-0.89; p=0.01). Below threshold rating on the VISS (score of 35) showed good agreement with the clinical ASD diagnosis (sensitivity 89%, specificity 100%). This preliminary study shows the VISS to be a promising schedule to aid the identification of ASD in young children with visual impairment.     

Motor stereotypies in children with autism and other developmental disorders

The purpose of the study was to count and characterize the range of stereotypies – repetitive rhythmical, apparently purposeless movements – in developmentally impaired children with and without autism, and to determine whether some types are more prevalent and diagnostically useful in children with autism. We described each motor stereotypy recorded during 15 minutes of archived videos of standardized play sessions in 277 children (209 males, 68 females; mean age 4y 6mo [SD 1y 5mo], range 2y 11mo–8y 1mo), 129 with autistic disorder (DSM-III-R), and 148 cognitively-matched non-autistic developmentally disordered (NADD) comparison children divided into developmental language disorder and non-autism, low IQ (NALIQ) sub-groups. The parts of the body involved and characteristics of all stereotypies were scored blind to diagnosis. More children with autism had stereotypies than the NADD comparison children. Autism and, to a lesser degree, nonverbal IQ (NVIQ) <80, especially in females contributed independently to the occurrence, number, and variety of stereotypies, with non-autistic children without cognitive impairment having the least number of stereotypies and children with autism and low NVIQ the most. Autism contributed independently to gait and hand/finger stereotypies and NVIQ <80 to head/trunk stereotypies. Atypical gazing at fingers and objects was rare but virtually limited to autism. Stereotypies are environmentally modulated movement disorders, some highly suggestive, but not pathognomonic, of autism. Their underlying brain basis and genetic correlates need investigation.     

Characterization of autism in young children with tuberous sclerosis complex

Both cognitive impairment and autism are common in the tuberous sclerosis complex, but the relationship between the 2 diagnoses has not been formally explored. The authors evaluated 20 clinic-referred children with tuberous sclerosis complex at ages 18, 24, 36, and 60 months and classified them as autism, autism spectrum disorder, or normal on the basis of the Autism Diagnostic Observation Schedule. Using the Mullen Scale of Early Learning, cognitive function in each subgroup was assessed. The authors then analyzed the subscores of the Autism Diagnostic Observation Schedule in children with autism. Children with autism showed significantly more global cognitive impairment than those without autism. In addition, all children had some baseline cognitive impairment and the majority had deficits in play scores. The authors conclude that clinic-referred children with tuberous sclerosis complex and autism are at considerable risk for cognitive impairment. These characteristics may help to guide more tailored services for these high-risk children.     

Motor abilities of children diagnosed with fragile X syndrome with and without autism

Background   Previous studies suggested that children diagnosed with fragile X syndrome (FXS) often meet criteria for autism or PDD. This study describes the fine motor abilities of children diagnosed with FXS with and without autism spectrum disorder, and compares the motor scores of those groups controlling for cognitive level.
Method   Forty-eight children, ages 12–76 months (SD = 16) diagnosed with FXS were assessed with the Mullen Scales of Early Learning, and the Autism Diagnostic Observation Schedule. Their parents were interviewed with the Autism Diagnostic Interview-Revised. We used a one-way analysis of variance to determine if the fine motor scale of the Mullen would show group differences based on autism classifications for the sample. In addition, we used Pearson correlation coefficient to examine the relationship between the cognitive level, the autism severity and the motor abilities. Lastly, we conducted a one-way analysis of covariance to determine the difference between the motor abilities of the Autism Spectrum Disorder groups controlling for cognitive level.
Results   We found that 60% of the children with FXS met criteria for autism or Pervasive Developmental Disorder – Not otherwise specified (PDD-NOS). Children with FXS with autism and PDD-NOS had lower fine motor scores than those without. However, there was no significant association between degree of motor impairment and communication and social impairments after controlling for cognitive level, indicating that cognitive level contributes to impaired motor abilities of children diagnosed with FXS and autism, more than the severity of autism symptoms.
Conclusion   children with FXS and autism are at risk for impaired motor abilities. Implications for development and intervention are discussed.     

The Autism Diagnostic Interview-Revised and the Childhood Autism Rating Scale: Differences Between Diagnostic Systems and Comparison Between Genders

Diagnoses for autism based on the Autism Diagnostic Interview-Revised (ADI-R) and the Childhood Autism Rating Scale (CARS) were examined for 83 individuals with suspected autism. Agreement between systems reached 85.7%. Participants receiving diagnosis of autism based on only one system were significantly younger in age than individuals receiving diagnoses according to both systems. Individuals who did not receive diagnosis of autism on the ADI-R had lower chronological and mental ages and lower CARS scores compared to individuals who received diagnosis of autism based on the ADI-R. Eighteen females and 18 males were matched to examine possible gender differences. No significant findings were revealed, suggesting that the symptoms of autism according to the ADI-R and CARS do not differ between males and females when matched for chronological and mental ages.     

Diagnostic Stability in Very Young Children with Autism Spectrum Disorders

Autism Spectrum Disorders (ASD) diagnosis in very young children may be delayed due to doubts about validity. In this study, 77 children received a diagnostic and developmental evaluation between 16 and 35 months and also between 42 and 82 months. Diagnoses based on clinical judgment, Childhood Autism Rating Scale, and the Autism Diagnostic Observation Schedule were stable over time. Diagnoses made using the Autism Diagnostic Interview were slightly less stable. According to clinical judgment, 15 children (19%) moved off the autism spectrum by the second evaluation; none moved onto the spectrum. Results indicate diagnostic stability at acceptable levels for diagnoses made at age 2. Movement off the spectrum may reflect true improvement based on maturation, intervention, or over-diagnosis at age 2.     

Differences in finger length ratio between males with autism, pervasive developmental disorder-not otherwise specified, ADHD, and anxiety disorders

Children with autism have a relatively shorter index finger (2D) compared with their ring finger (4D). It is often presumed that the 2D:4D ratio is associated with fetal testosterone levels and that high fetal testosterone levels could play a role in the aetiology of autism. It is unknown whether this effect is specific to autism. In this study, 2D:4D ratios of 144 males aged 6 to 14 years (mean age 9y 1 mo [SD 1y 11 mo]) with psychiatric disorders were compared with those of 96 males aged 6 to 13 years from the general population (mean age 9y 1 mo [SD 1y 10 mo]). Psychiatric disorders were divided into autism/Asperger syndrome (n=24), pervasive developmental disorder-not otherwise specified (PDD-NOS; n=26), attention-deficit-hyperactivity disorder (ADHD)/oppositional defiant disorder (ODD; n=68), and anxiety disorders (n=26). Males with autism/Asperger syndrome (p<0.05) and ADHD/ODD (p<0.05) had significantly lower (though not significantly; p=0.52) ratios than males with an anxiety disorder, and males with autism/Asperger syndrome had lower ratios than those in the comparison group. These results indicated that higher fetal testosterone levels may play a role, not only in the origin of autism, but also in the aetiology of PDD-NOS and of ADHD/ODD. Males with anxiety disorders might have been exposed to lower prenatal testosterone levels.     

Sex chromosomes and the brain: a study of neuroanatomy in XYY syndrome

Aim To assess global and regional brain matter variations associated with XYY syndrome by comparison with Klinefelter syndrome and typical development. Methods We used two conceptually distinct voxel‐based magnetic resonance imaging methods to examine brain structure in young males with XYY syndrome: (1) volumetric comparison to assess global grey and white matter volumes and (2) support vector machine‐based multivariate pattern classification analysis to assess regional neuroanatomy. We assessed verbal, non‐verbal, and spatial abilities with the Differential Ability Scales (DAS), and we measured autism diagnostic criteria in eight males with XYY syndrome using the Social Responsiveness Scale and the Autism Diagnostic Interview‐Revised (ADI‐R). Results A comparison of 36 typically developing males (mean age 11y, SD 1y 9mo), 31 males with Klinefelter syndrome (mean age 9y 8mo, SD 1y 8mo), and eight males with XYY syndrome (mean age 11y 6mo, SD 1y 11mo) showed that total white and grey matter volumes were significantly, or nearly significantly, higher in males with XYY syndrome than in males belonging to the other two groups (grey matter: XYY males vs typically developing males, p<0.006; XYY vs males with Klinefelter syndrome, p<0.001; white matter: XYY males vs typically developing males, p=0.061; XYY males vs males with Klinefelter syndrome, p=0.004). Voxel‐based multivariate pattern classification analysis indicates that, after controlling for global volumes, regional brain variations in XYY syndrome are more like those found in Klinefelter syndrome than those occurring in typical development. Further, visualization of classification parameters suggests that insular and frontotemporal grey matter and white matter, including known language areas, are reduced in males with XYY syndrome, similar to what is seen in Klinefelter syndrome. In males with XYY syndrome, DAS verbal and non‐verbal scores were significantly lower than in typically developing participants (both p<0.001). DAS scores were not significantly different between XYY and Klinefelter syndrome groups. In five of eight males with XYY syndrome, the Social Responsiveness Scale score exceeded the cut‐off for a likely diagnosis of autism spectrum disorder (ASD). In three of eight males with XYY syndrome, the ADI‐R score met the cut‐off for ASD diagnosis; in another two, ADI‐R scores within the social and communication domains met the cut‐off values for a diagnosis of ASD. Interpretation The results suggest that genetic variations associated with XYY syndrome result in increased brain matter volumes, a finding putatively related to the increased frequency of ASDs in individuals with this condition. In addition, frontotemporal grey and white matter reductions in XYY syndrome provide a likely neuroanatomical correlate for observed language impairments.