Discriminant analysis of the Ullrich-Turner syndrome neurocognitive profile

Clinical developmental, neuropsychological, and social-emotional features of Turner syndrome

Individuals with Turner syndrome (TS) are at risk for a constellation of neurocognitive and psychosocial differences, although there is significant individual variability in these features. TS is associated with an increased risk for difficulties with visual-spatial reasoning, visual-spatial memory, attention, executive functioning, motor, and math skills. Additionally, increased rates of social difficulties, anxiety, and depression are observed. There can be significant interplay between all of these factors contributing to the behavioral phenotype. Neuropsychological features and previous research are reviewed. Clinical considerations and recommendations for evaluation and treatment of psychological and behavioral difficulties are provided, including consideration of medical features in TS, as well as therapies, educational supports, and medication treatment. Future research is needed to evaluate effectiveness of different treatments for neuropsychological and psychosocial features of TS, including modification and validation of existing evidence-based treatments and new approaches to care.

Sex differences in psychiatric disorders: what we can learn from sex chromosome aneuploidies

The study of sexual dimorphism in psychiatric and neurodevelopmental disorders is challenging due to the complex interplay of diverse biological, psychological, and social factors. Males are more susceptible to neurodevelopmental disorders including intellectual disability, autism spectrum disorder, and attention-deficit activity disorder. Conversely, after puberty, females are more prone to major depressive disorder and anxiety disorders compared to males. One major biological factor contributing to sex differences is the sex chromosomes. First, the X and Y chromosomes have unique and specific genetic effects as well as downstream gonadal effects. Second, males have one X chromosome and one Y chromosome, while females have two X chromosomes. Thus, sex chromosome constitution also differs between the sexes. Due to this complexity, determining genetic and downstream biological influences on sexual dimorphism in humans is challenging. Sex chromosome aneuploidies, such as Turner syndrome (X0) and Klinefelter syndrome (XXY), are common genetic conditions in humans. The study of individuals with sex chromosome aneuploidies provides a promising framework for studying sexual dimorphism in neurodevelopmental and psychiatric disorders. Here we will review and contrast four syndromes caused by variation in the number of sex chromosomes: Turner syndrome, Klinefelter syndrome, XYY syndrome, and XXX syndrome. Overall we describe an increased rate of attention-deficit hyperactivity disorder and autism spectrum disorder, along with the increased rates of major depressive disorder and anxiety disorders in one or more of these conditions. In addition to contributing unique insights about sexual dimorphism in neuropsychiatric disorders, awareness of the increased risk of neurodevelopmental and psychiatric disorders in sex chromosome aneuploidies can inform appropriate management of these common genetic disorders.

Face perception in women with Turner syndrome and its underlying factors

Turner syndrome (TS) is a chromosomal condition that affects development in females. It is characterized by short stature, ovarian failure and other congenital malformations, due to a partial or complete absence of the sex chromosome. Women with TS frequently suffer from various physical and hormonal dysfunctions, along with impairments in visual-spatial processing and social cognition difficulties. Previous research has also shown difficulties in face and emotion perception. In the current study we examined two questions: First, whether women with TS, that are impaired in face perception, also suffer from deficits in face-specific processes. The second question was whether these face impairments in TS are related to visual-spatial perceptual dysfunctions exhibited by TS individuals, or to impaired social cognition skills. Twenty-six women with TS and 26 control participants were tested on various cognitive and psychological tests to assess visual-spatial perception, face and facial expression perception, and social cognition skills. Results show that women with TS were less accurate in face perception and facial expression processing, yet they exhibited normal face-specific processes (configural and holistic processing). They also showed difficulties in spatial perception and social cognition capacities. Additional analyses revealed that their face perception impairments were related to their deficits in visual-spatial processing. Thus, our results do not support the claim that the impairments in face processing observed in TS are related to difficulties in social cognition. Rather, our data point to the possibility that face perception difficulties in TS stem from visual-spatial impairments and may not be specific to faces.

Empathy, autistic traits, and motor resonance in adults with Turner syndrome

Turner syndrome is a genetic condition resulting from the partial or complete absence of an X-chromosome in phenotypic females. Individuals with Turner syndrome often display social difficulties that are reminiscent of those associated with autistic spectrum disorders (ASD), conditions associated with empathy and mirror-neuron system (MNS) deficits. The goal of the present study was (1) to investigate the extent to which adults with Turner syndrome display autistic and empathic traits, and (2) to probe the integrity of the MNS in this neurogenetic disorder. Sixteen individuals with Turner syndrome and 16 age-, sex-, and IQ-matched controls took part in a neuropsychological assessment where the Weschler Abbreviated Scale of Intelligence, the Autism Spectrum Quotient and the Empathy Quotient were administered. Functioning of the MNS was assessed by measuring motor cortex activity with transcranial magnetic stimulation during an action-observation task. Results show that individuals with Turner syndrome do not differ significantly from controls regarding autistic or empathic traits, and present normal functioning of the MNS during action observation. Correlational analysis showed a significant positive relationship between scores on the Empathy Quotient and motor facilitation during action observation, bringing further support to the hypothesis that MNS activity is related to sociocognitive competence.

Impact of cognitive profile on social functioning in prepubescent females with Turner syndrome

Social deficits are prevalent in Turner syndrome (TS); however, the extent to which these difficulties are secondary to characteristic cognitive impairments is not well known. Here, we sought to establish the relative contribution of executive functions, visuospatial abilities, and IQ to social difficulties in young girls with TS. Forty TS girls and 19 typically developing (TD) children were assessed with the Social Responsiveness Scale (SRS), the Motor-Free Visual Spatial Test (MVPT-3), the Behavior Rating Inventory of Executive Function (BRIEF), and an IQ test. Hierarchical multiple regression analyses were conducted with the SRS subscales as outcome variables. In a first step, the cognitive factors were entered (verbal IQ, BRIEF global score, MVPT-3, and age), followed by the group variable in a second step. In comparison to TD, TS participants were significantly impaired on all main measures. All six regression models with the SRS subscales were significant and revealed that global executive functions explained the largest portion of the variance on all subscales and the total score. Even after controlling for cognitive elements, the group factor still explained a significant portion of the variance of the Social Cognition, Social Awareness, and Autistic Mannerisms subscales. In contrast, the group factor was not a significant predictor of Social Motivation and Social Communication scores. These results suggest that executive dysfunctions play a role in social impairments encountered in TS, but also that some specific aspects of social behavior are altered beyond what can be attributed to cognitive difficulties in this population.

Psychosocial functioning and social cognitive processing in girls with Turner syndrome

OBJECTIVE

Turner syndrome (TS) is a common genetic disorder caused by partial or complete absence of the second X chromosome in females and is associated with a characteristic neurocognitive profile traditionally described by discrepancy between verbal and performance IQ. Difficulties in social functioning have also been increasingly identified in this population. The purpose of this study was to examine elements of social competence and cognition in a pre-estrogen population of girls with TS.

METHODS

The authors administered psychosocial and neurocognitive measures to examine metrics of social function and intelligence in a group of young girls with TS, pre-estrogen treatment (n = 42) and control peers (n = 32), aged between 3 and 12 years.

RESULTS

Girls with TS demonstrated significantly decreased social competency on all dimensions of the Social Responsiveness Scale, with the exception of the Social Motivation subscale, where ratings were comparable with typically developing peers. Performance on social cognitive tasks was also impaired on NEPSY Memory for Faces and Theory of Mind tasks. Differences were further observed on Behavioral Assessment Scales for Children subscales of Hyperactivity, Atypicality, Attention, Social Skills, Activities of Daily Living, and Functional Communication. Group differences in social cognition or behavior remained significant after adjusting for verbal IQ.

CONCLUSION

This study supports the hypothesis that young girls with TS who have not yet received estrogen treatment demonstrate significantly impaired social cognition. Improved understanding of differences in social competence and cognition can increase awareness and inform clinical approaches to identifying and treating social difficulties in individuals with TS.

Developmental malformation of the corpus callosum: a review of typical callosal development and examples of developmental disorders with callosal involvement

This review provides an overview of the involvement of the corpus callosum (CC) in a variety of developmental disorders that are currently defined exclusively by genetics, developmental insult, and/or behavior. I begin with a general review of CC development, connectivity, and function, followed by discussion of the research methods typically utilized to study the callosum. The bulk of the review concentrates on specific developmental disorders, beginning with agenesis of the corpus callosum (AgCC)-the only condition diagnosed exclusively by callosal anatomy. This is followed by a review of several genetic disorders that commonly result in social impairments and/or psychopathology similar to AgCC (neurofibromatosis-1, Turner syndrome, 22q11.2 deletion syndrome, Williams yndrome, and fragile X) and two forms of prenatal injury (premature birth, fetal alcohol syndrome) known to impact callosal development. Finally, I examine callosal involvement in several common developmental disorders defined exclusively by behavioral patterns (developmental language delay, dyslexia, attention-deficit hyperactive disorder, autism spectrum disorders, and Tourette syndrome).

Cognitive profile of Turner syndrome

Turner syndrome (TS) is a relatively common neurogenetic disorder characterized by complete or partial monosomy-X in a phenotypic female. TS is associated with a cognitive profile that typically includes intact intellectual function and verbal abilities with relative weaknesses in visual-spatial, executive, and social cognitive domains. In this report, we review previous and current research related to the cognitive profile of TS. We also discuss how cognitive impairments in this syndrome may reflect integrative rather than modular deficits. For example, the less commonly reported areas of verbal difficulty in TS and certain visual-spatial deficits seem significantly influenced by impairments in executive function and spatially loaded stimuli. We provide a summary of cognitive testing measures used in the assessment of visual-spatial and executive skills, which includes test domain descriptions as well as a comprehensive examination of social cognitive function in TS. This review concludes with a discussion of ecological interpretations regarding the meaning of cognitive deficits in TS at the individual level.

Syndrome diagnosis: human intuition or machine intelligence?

The aim of this study was to investigate whether artificial intelligence methods can represent objective methods that are essential in syndrome diagnosis. Most syndromes have no external criterion standard of diagnosis. The predictive value of a clinical sign used in diagnosis is dependent on the prior probability of the syndrome diagnosis. Clinicians often misjudge the probabilities involved. Syndromology needs objective methods to ensure diagnostic consistency, and take prior probabilities into account. We applied two basic artificial intelligence methods to a database of machine-generated patients - a 'vector method' and a set method. As reference methods we ran an ID3 algorithm, a cluster analysis and a naive Bayes' calculation on the same patient series. The overall diagnostic error rate for the the vector algorithm was 0.93%, and for the ID3 0.97%. For the clinical signs found by the set method, the predictive values varied between 0.71 and 1.0. The artificial intelligence methods that we used, proved simple, robust and powerful, and represent objective diagnostic methods.

Paternal X could relate to arithmetic function; study of cognitive function and parental origin of X chromosome in Turner syndrome

BACKGROUND

45,X Turner syndrome (TS) female subjects have visuospatial skill and social cognition deficits that may arise from X-linked imprinting. The aim of the present study was to compare phenotypic characteristics and neurocognitive pattern of 12 monosomic TS girls, according to X-linked imprinting.

METHODS

Microsatellite markers were used to determine the parental origin of the missing chromosome X. Wechsler Intelligence Scale for Children-Revised (WISC-R) was administered as measures of general intellectual functioning. The results were compared in TS patients with maternally derived X chromosome (Xm) and paternally derived X chromosome (Xp).

RESULTS

Six out of 12 patients (50%) had Xm, and the other six (50%) had Xp chromosome. There was no difference in the total, verbal and performance IQ score between the TS subgroups with Xm and Xp. When the WISC-R subtest score patterns were compared, the mean arithmetic scores were significantly poorer in the Xm TS than in the Xp TS.

CONCLUSION

In monosomic TS cases, paternal imprinting may predict arithmetic ability, on the other hand, reductionist consideration defined by genetic imprinting is not sufficient to confirm this. Further studies should be undertaken to clarify this situation.

Turner Syndrome

Turner syndrome is a neurogenetic disorder characterized by partial or complete monosomy-X. It is associated with certain physical and medical features, including estrogen deficiency, short stature, and increased risk for several diseases, with cardiac conditions being among the most serious. The cognitive-behavioral phenotype associated with the syndrome includes strengths in verbal domains with impairments in visuospatial, executive function, and emotion processing. Less is known regarding psychosocial and psychiatric functioning in Turner syndrome, but essential aspects of psychotherapeutic treatment plans are suggested. Future investigations should include continued genetic studies and determination of candidate genes for physical and cognitive features. Multimodal, interdisciplinary studies are essential for identifying optimal, syndrome-specific interventions for improving the lives of individuals who have Turner syndrome.

A Turner syndrome neurocognitive phenotype maps to Xp22.3

BACKGROUND

Turner syndrome (TS) is associated with a neurocognitive phenotype that includes selective nonverbal deficits, e.g., impaired visual-spatial abilities. We previously reported evidence that this phenotype results from haploinsufficiency of one or more genes on distal Xp. This inference was based on genotype/phenotype comparisons of individual girls and women with partial Xp deletions, with the neurocognitive phenotype considered a dichotomous trait. We sought to confirm our findings in a large cohort (n = 47) of adult women with partial deletions of Xp or Xq, enriched for subjects with distal Xp deletions.

METHODS

Subjects were recruited from North American genetics and endocrinology clinics. Phenotype assessment included measures of stature, ovarian function, and detailed neurocognitive testing. The neurocognitive phenotype was measured as a quantitative trait, the Turner Syndrome Cognitive Summary (TSCS) score, derived from discriminant function analysis. Genetic analysis included karyotyping, X inactivation studies, fluorescent in situ hybridization, microsatellite marker genotyping, and array comparative genomic hybridization.

RESULTS

We report statistical evidence that deletion of Xp22.3, an interval containing 31 annotated genes, is sufficient to cause the neurocognitive phenotype described by the TSCS score. Two other cardinal TS features, ovarian failure and short stature, as well as X chromosome inactivation pattern and subject's age, were unrelated to the TSCS score.

CONCLUSION

Detailed mapping suggests that haploinsufficiency of one or more genes in Xp22.3, the distal 8.3 megabases (Mb) of the X chromosome, is responsible for a TS neurocognitive phenotype. This interval includes the 2.6 Mb Xp-Yp pseudoautosomal region (PAR1). Haploinsufficiency of the short stature gene SHOX in PAR1 probably does not cause this TS neurocognitive phenotype. Two genes proximal to PAR1 within the 8.3 Mb critical region, STS and NLGN4X, are attractive candidates for this neurocognitive phenotype.

Cognition and the sex chromosomes: studies in Turner syndrome

Turner syndrome (TS) is a human genetic disorder involving females who lack all or part of one X chromosome. The complex phenotype includes ovarian failure, a characteristic neurocognitive profile and typical physical features. TS features are associated not only with complete monosomy X but also with partial deletions of either the short (Xp) or long (Xq) arm (partial monosomy X). Impaired visual-spatial/perceptual abilities are characteristic of TS children and adults of varying races and socioeconomic status, but global developmental delay is uncommon. The cognitive phenotype generally includes normal verbal function with relatively impaired visual-spatial ability, attention, working memory, and spatially dependent executive function. The constellation of neurocognitive deficits observed in TS is most likely multifactorial and related to a complex interaction between genetic abnormalities and hormonal deficiencies. Furthermore, other determinants, including an additional genetic mechanism, imprinting, may also contribute to cognitive deficits associated with monosomy X. As a relatively common genetic disorder with well-defined manifestations, TS presents an opportunity to investigate genetic and hormonal factors that influence female cognitive development. TS is an excellent model for such studies because of its prevalence, the well-characterized phenotype, and the wealth of molecular resources available for the X chromosome. In the current review, we summarize the hormonal and genetic factors that may contribute to the TS neurocognitive phenotype. The hormonal determinants of cognition in TS are related to estrogen and androgen deficiency. Our genetic hypothesis is that haploinsufficiency for gene/genes on the short arm of the X chromosome (Xp) is responsible for the hallmark features of the TS cognitive phenotype. Careful clinical and molecular characterization of adult subjects missing part of Xp links the TS phenotype of impaired visual spatial/perceptual ability to specific distal Xp chromosome regions. We demonstrate that small, nonmosaic deletion of the distal short arm of the X chromosome in adult women is associated with the same hallmark cognitive profile seen in adult women with TS. Future studies will elucidate the cognitive deficits and the underlying etiology. These results should allow us to begin to design cognitive interventions that might lessen those deficits in the TS population.

Interpreting gaze in Turner syndrome: impaired sensitivity to intention and emotion, but preservation of social cueing

Women with Turner's syndrome (TS), who lack a complete X-chromosome, show an impairment in remembering faces and in classifying "fear" in face images. Could their difficulties extend to the processing of gaze? Three tasks, all of which rely on the ability to make use of the eye-region of a pictured face, are reported. Women with TS were impaired at judging mental state from images of the upper face ("reading the mind in the eyes"). They were also specifically impaired at interpreting "fear" from displays of the eye-region of the face. However, they showed normal susceptibility to direction of gaze as an attentional cue (social cueing), since they were as sensitive as controls to the validity of the cue, under conditions where it should be ignored. In this task, unlike those of reading the upper face for intention or expression, PIQ accounted for a significant amount of individual variance in task performance. The processing of displays of the eye region affording social and affective information is specifically affected in TS. We speculate that amygdala dysfunction is likely to be implicated in this anomalous behaviour. The presence in the female karyotype of two complete X-chromosomes is protective for some socio-cognitive abilities related to the modulation of behaviour by the interpretation of gaze.

The Turner syndrome-associated neurocognitive phenotype maps to distal Xp

Turner syndrome (TS) is associated with a characteristic neurocognitive profile that includes impaired visuospatial/perceptual abilities. We used a molecular approach to identify a critical region of the X chromosome for neurocognitive aspects of TS. Partial deletions of Xp in 34 females were mapped by FISH or by loss of heterozygosity of polymorphic markers. Discriminant function analysis optimally identified the TS-associated neurocognitive phenotype. Only subjects missing approximately 10 Mb of distal Xp manifested the specified neurocognitive profile. The phenotype was seen with either paternally or maternally inherited deletions and with either complete or incomplete skewing of X inactivation. Fine mapping of informative deletions implicated a critical region of <2 Mb within the pseudoautosomal region (PAR1). We conclude that haploinsufficiency of PAR1 gene(s) is the basis for susceptibility to the TS neurocognitive phenotype.

Quality of life in Turner syndrome is related to chromosomal constitution: implications for genetic counselling and management

Issues of self-appraisal, friendships and academic attainments are uniquely salient for all adolescents. For girls with Turner syndrome, social problems and learning difficulties often become more serious at this time, yet may be unacknowledged by those responsible for paediatric care because their focus is on growth and sexual maturation. Data on the social and educational adjustment of 110 45,X (monosomic) females aged between 6 and 25 years is presented. Detailed information on the patients' precise karyotype was used to demonstrate systematic differences in adjustment between those whose single X chromosome was maternally derived and those in whom it was paternal. Implications for educational support and parental guidance are discussed.

Turner syndrome and haploinsufficiency

Turner syndrome was one of the first human genetic disorders ascribed to haploinsufficiency but the identification of specific genes responsible for the phenotype has been problematic. Recent data point to several candidate genes, some new and some old, for specific aspects of the phenotype associated with monosomy X in humans.