Ullrich-Turner syndrome: neurodevelopmental changes from childhood through adolescence

The contribution of Xp22.31 gene dosage to Turner and Klinefelter syndromes and sex-biased phenotypes

Turner syndrome (TS) is a rare developmental condition in females caused by complete, or partial, loss of the second sex chromosome; it is associated with a number of phenotypes including short stature, ovarian failure and infertility, as well as neurobehavioural and cognitive manifestations. In contrast, Klinefelter syndrome (KS) arises from an excess of X chromosome material in males (typical karyotype is 47,XXY); like TS, KS is associated with infertility and hormonal imbalance, and behavioural/neurocognitive differences from gonadal sex-matched counterparts. Lower dosage of genes that escape X-inactivation may partially explain TS phenotypes, whilst overdosage of these genes may contribute towards KS-related symptoms. Here, I discuss new findings from individuals with deletions or duplications limited to Xp22.31 (a region escaping X-inactivation), and consider the extent to which altered gene dosage within this small interval (and of the steroid sulfatase (STS) gene in particular) may influence the phenotypic profiles of TS and KS. The expression of X-escapees can be higher in female than male tissues; I conclude by considering how lower Xp22.31 gene dosage in males may increase their likelihood of exhibiting particular phenotypes relative to females. Understanding the genetic contribution to specific phenotypes in rare disorders such as TS and KS, and to more common sex-biased phenotypes, will be important for developing more effective, and more personalised, therapeutic approaches.

Reversal Learning Performance in the XY∗ Mouse Model of Klinefelter and Turner Syndromes

Klinefelter syndrome (KS; 47, XXY) and Turner syndrome (TS; 45, XO) are caused by two relatively common sex chromosome aneuploidies. These conditions are associated with an increased odds of neuropsychiatric disorders, including attention deficit/hyperactivity disorder (ADHD), as well as impairments in cognition that include learning delays, attentional dysfunction and impulsivity. We studied cognitive functions in the XY^∗ mouse model, which allows comparison of XXY to XY males (KS model), and XO to XX females (TS model). We evaluated adult mice with and without gonads, using a version of an operant reversal-learning task (RLT) that can be used to measure various facets of learning, impulsivity and attention. In the KS model, only one measure related to impulsivity – perseverative responding under reversal conditions – reliably discriminated gonadally intact XXY and XY mice. In contrast, a fundamental learning impairment (more trials to criterion in acquisition phase) in XXY mice, as compared to XY, was observed in gonadectomized subjects. No other task measures showed differences consistent with KS. In the TS mouse model, XO mice did not show a pattern of results consistent with TS, similar to past observations. Thus, the application of this RLT to these XY^∗ models reveals only limited behavioral impairments relevant to KS.

Perception of Emotional Prosody: Moving Toward a Model That Incorporates Sex-Related Differences

The overall purpose of this article is to review the literature that addresses the theoretical models, neuroanatomical mechanisms, and sex-related differences in the perception of emotional prosody. Specifically, the article focuses on the right-hemisphere model of emotion processing as it pertains to the perception of emotional prosody. This article also reviews more recent research that implicates a role for the left hemisphere and subcortical structures in the perception of emotional prosody. The last major section of this article addresses sex-related differences and the potential influence of hormones on the perception of emotional prosody. The article concludes with a section that offers directions for future research.

Elucidating X chromosome influences on Attention Deficit Hyperactivity Disorder and executive function

OBJECTIVE

To identify distinct behavioral and cognitive profiles associated with ADHD in Turner syndrome (TS), relative to idiopathic ADHD and neurotypical controls, in order to elucidate X-linked influences contributing to ADHD.

METHODS

We used a multilevel-model approach to compare 49 girls with TS to 37 neurotypical females, aged 5-12, on established measures of behavior (BASC-2) and neurocognitive function (NEPSY). We further compared girls with TS to BASC-2 and NEPSY age-matched reference data obtained from children with idiopathic ADHD.

RESULTS

Within the TS group, 51% scored at or above the "at-risk" range for ADHD-associated behaviors on the BASC-2 (TS/+ADHD). The BASC-2 behavioral profile in this TS/+ADHD-subgroup was comparable to a reference group of boys with ADHD with respect to attentional problems and hyperactivity. However, the TS/+ADHD-subgroup had significantly higher hyperactivity scores relative to a reference sample of girls with ADHD (p = 0.016). The behavioral profile in TS was associated with significantly lower attention and executive function scores on the NEPSY relative to neurotypical controls (p = 0.015); but was comparable to scores from a reference sample of children with idiopathic ADHD. Deficits in attention and executive function were not observed in girls with TS having low levels of ADHD-associated behavior (TS/-ADHD).

CONCLUSIONS

ADHD-associated behavioral and cognitive problems in TS are prevalent and comparable in severity to those found in children with idiopathic ADHD. The ADHD phenotype in TS also appears relatively independent of cognitive features typically associated with TS, like visuospatial weaknesses. These findings suggest that X-linked haploinsufficiency and downstream biological effects contribute to increased risk for ADHD.

Gender based variation in cognitive functions in adolescent subjects

Background

Cognition can be defined as all mental activities that are involved in acquisition, processing, storage and retrieval of information.

Purpose

There is paucity of the data related to cognitive function amongst healthy adolescent age group which limits our ability to distinguish and compare cognitive changes that occur across the adult lifespan in female and male subjects separately and can provide some help to understand dementia related conditions.

Methods

Cognitive function was assessed in 100 healthy subjects of each sex of 17–20 years by using ‘Montreal Cognition Assessment Test’, a 10 minutes: 30-points test which is used in assessing a wide range of cognitive abilities on 7 subscales : 1) Visuospatial Skills, 2) Language, 3) Memory, 4) Attention, 5) Mathematical ability, 6) Abstraction, and 7) Orientation.

Results

Overall score (Male: 25.16 ± 1.8, Female: 25.72 ± 1.8) of cognition functions was statistically significantly higher in female adolescents (p=<0.02). However male subjects showed higher score in Mathematical ability.

Conclusion

There are variations in the cognitive functions in male and female individuals and neuroanatomical and physiological differences contribute to these variations.

Functional plasticity in childhood brain disorders: when, what, how, and whom to assess

At every point in the lifespan, the brain balances malleable processes representing neural plasticity that promote change with homeostatic processes that promote stability. Whether a child develops typically or with brain injury, his or her neural and behavioral outcome is constructed through transactions between plastic and homeostatic processes and the environment. In clinical research with children in whom the developing brain has been malformed or injured, behavioral outcomes provide an index of the result of plasticity, homeostasis, and environmental transactions. When should we assess outcome in relation to age at brain insult, time since brain insult, and age of the child at testing? What should we measure? Functions involving reacting to the past and predicting the future, as well as social-affective skills, are important. How should we assess outcome? Information from performance variability, direct measures and informants, overt and covert measures, and laboratory and ecological measures should be considered. In whom are we assessing outcome? Assessment should be cognizant of individual differences in gene, socio-economic status (SES), parenting, nutrition, and interpersonal supports, which are moderators that interact with other factors influencing functional outcome.

Aberrant parietal cortex developmental trajectories in girls with Turner syndrome and related visual-spatial cognitive development: a preliminary study

Turner syndrome (TS) arises from partial or complete absence of the X-chromosome in females. Girls with TS show deficits in visual-spatial skills as well as reduced brain volume and surface area in the parietal cortex which supports these cognitive functions. Thus, measuring the developmental trajectory of the parietal cortex and the associated visual-spatial cognition in TS may provide novel insights into critical brain-behavior associations. In this longitudinal study, we acquired structural MRI data and assessed visual-spatial skills in 16 (age: 8.23 ± 2.5) girls with TS and 13 age-matched controls over two time-points. Gray and white matter volume, surface area and cortical thickness were calculated from surfaced based segmentation of bilateral parietal cortices, and the NEPSY Arrows subtest was used to assess visual-spatial ability. Volumetric and cognitive scalars were modeled to obtain estimates of age-related change. The results show aberrant growth of white matter volume (P = 0.011, corrected) and surface area (P = 0.036, corrected) of the left superior parietal regions during childhood in girls with TS. Other parietal sub-regions were significantly smaller in girls with TS at both time-points but did not show different growth trajectories relative to controls. Furthermore, we found that visual-spatial skills showed a widening deficit for girls with TS relative to controls (P = 0.003). Young girls with TS demonstrate an aberrant trajectory of parietal cortical and cognitive development during childhood. Elucidating aberrant neurodevelopmental trajectories in this population is critical for determining specific stages of brain maturation that are particularly dependent on TS-related genetic and hormonal factors.

Assessing gonadal hormone contributions to affective psychopathologies across humans and animal models

Despite increasing acknowledgement of hormonal contributions to mood and anxiety disorders, the underlying mechanisms by which gonadal hormones influence psychopathology-related behaviours remain unknown. This review focuses on recent research that examines the influence of gonadal steroid hormones, including androgens, oestrogens, and progesterone, on mood and anxiety-related behaviours in human health and disease. To this aim, the literature was surveyed for studies that assess conditions with suspected underlying hormonal imbalances in otherwise healthy participants (e.g., premenstrual dysphoric disorder, postmenopausal depression) as well as conditions linked to congenital endocrine abnormalities (e.g., Turner Syndrome, Klinefelter Syndrome, polycystic ovary syndrome, congenital adrenal hyperplasia, familial male precocious puberty, androgen insensitivity syndrome). Furthermore, to better inform clinical work and to create a translational bridge, a second goal was to set human psychopathologies and animal models of these conditions side-by-side. In the second part of the review, based on consistencies revealed in the existing literature across conditions, a new model for the impact of gonadal hormones on anxious and depressed behavioural states is proposed. Finally, we conclude by proposing directions for future research, including the development of specific tasks suitable for cross-species comparisons to increase our knowledge of the role of gonadal hormones in mood and anxiety.

Sex hormone replacement in Turner syndrome

The cardinal features of Turner syndrome (TS) are short stature, congenital abnormalities, infertility due to gonadal dysgenesis, with sex hormone insufficiency ensuing from premature ovarian failure, which is involved in lack of proper development of secondary sex characteristics and the frequent osteoporosis seen in Turner syndrome. But sex hormone insufficiency is also involved in the increased cardiovascular risk, state of physical fitness, insulin resistance, body composition, and may play a role in the increased incidence of autoimmunity. Severe morbidity and mortality affects females with Turner syndrome. Recent research emphasizes the need for proper sex hormone replacement therapy (HRT) during the entire lifespan of females with TS and new hypotheses concerning estrogen receptors, genetics and the timing of HRT offers valuable new information. In this review, we will discuss the effects of estrogen and androgen insufficiency as well as the effects of sex HRT on morbidity and mortality with special emphasis on evidence based research and areas needing further studies.

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.

Psychiatric features in children with genetic syndromes: toward functional phenotypes

Neurodevelopmental disorders with identified genetic etiologies present a unique opportunity to study gene-brain-behavior connections in child psychiatry. Parsing complex human behavior into dissociable components is facilitated by examining a relatively homogenous genetic population. As children with developmental delay carry a greater burden of mental illness than the general population, familiarity with the most common genetic disorders will serve practitioners seeing a general child population. In this article, basic genetic testing and 11 of the most common genetic disorders are reviewed, including the evidence base for treatment. Based on their training in child development, family systems, and multimodal treatment, child psychiatrists are well positioned to integrate cognitive, behavioral, social, psychiatric, and physical phenotypes, with a focus on functional impairment.

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).

Psychiatric features in children with genetic syndromes: toward functional phenotypes

Neurodevelopmental disorders with identified genetic etiologies present a unique opportunity to study gene-brain-behavior connections in child psychiatry. Parsing complex human behavior into dissociable components is facilitated by examining a relatively homogenous genetic population. As children with developmental delay carry a greater burden of mental illness than the general population, familiarity with the most common genetic disorders will serve practitioners seeing a general child population. In this article basic genetic testing and 11 of the most common genetic disorders are reviewed, including the evidence base for treatment. Based on their training in child development, family systems, and multimodal treatment, child psychiatrists are well positioned to integrate cognitive, behavioral, social, psychiatric, and physical phenotypes, with a focus on functional impairment.

EFHC2 SNP rs7055196 is not associated with fear recognition in 45,X Turner syndrome

The neurocognitive phenotype of Turner syndrome (TS) includes deficits in social cognitive skills such as recognition of the facial affect expressing fear. A TS social cognition locus was previously mapped to a 5 megabase interval of Xp11.3-p11.4 by Good et al. 2003. A recent study by these same workers found evidence for association of a SNP in the EFHC2 gene, rs7055196, within this interval with fear recognition in 45,X TS. As EFHC2 was not a biological candidate gene for this phenotype a priori, we sought to replicate their finding in an independent cohort of 45,X TS subjects, using the same instrument to measure facial affect fear recognition. In contrast to the previous results, we find no evidence of an association between rs7055196 genotype and fear recognition. Other variations in EFHC2 and other candidate genes should be tested for association with social cognition in 45,X TS.

What it is said versus how it is said: comprehension of affective prosody in men with Klinefelter (47,XXY) syndrome

Difficulties in social communication in individuals with Klinefelter syndrome (XXY chromosomal pattern) have largely been attributed to deficits in left hemisphere-mediated, language functions. This study examined the ability of XXY men to decode emotions from tone of voice, a pragmatic aspect of social communication that may be associated with right hemisphere functioning. A total of 26 XXY men and 20 men from the general population completed tasks involving emotion discrimination in speech, based on verbal content or tone of voice. The XXY group displayed relative difficulties in discriminating emotions in tone of voice, and, to a lesser extend, in verbal content. This finding suggests that the XXY chromosomal pattern may not only be associated with difficulties in semantic aspects of language, but with prosodic aspects, as well. Our findings may contribute to the development of more comprehensive models addressing the role of the X chromosome in normal and abnormal development of social communication.

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.

X-monosomy effects on visuospatial attention in mice: a candidate gene and implications for Turner syndrome and attention deficit hyperactivity disorder

BACKGROUND

The loss of all, or part of an X chromosome, in Turner syndrome (TS, 45,XO) results in deficits in attentional functioning.

METHODS

Using a 39,XO mouse model, we tested the hypothesis that X-monosomy and/or parental origin of the single X chromosome may influence visuospatial attentional functioning in a 5-choice serial reaction time task (5-CSRTT).

RESULTS

Under attentionally demanding conditions 39,XO mice displayed impaired discriminative response accuracy and slowed correct reaction times relative to 40,XX mice; these deficits were alleviated in a version of the task with reduced attentional demands. Parental origin of the X did not affect performance of the 5-CSRTT. In contrast, the attentional phenotype was rescued in 40,XY*X mice possessing a single maternally inherited X chromosome and a small Y*X chromosome that comprises a complete pseudoautosomal region (PAR), and a small X-specific segment.

CONCLUSIONS

Our findings are consistent with an X-monosomy effect on attention and suggest the existence of X-linked gene(s) that escape X-inactivation, are present on the small Y*X chromosome and impact on attentional functioning; the strongest candidate gene is Sts, encoding steroid sulfatase. The data inform the TS literature and indicate novel genetic mechanisms that may be of general significance to the neurobiology of attention.

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.

The 39,XO mouse as a model for the neurobiology of Turner syndrome and sex-biased neuropsychiatric disorders

Turner syndrome (TS) is a developmental disorder most frequently arising from the loss of a complete X chromosome (karyotype 45,XO). The disorder is characterised by physiological abnormalities (notably short stature and ovarian dysfunction), emotional anomalies (including heightened anxiety) and by a neuropsychological profile encompassing deficits in visuospatial skills, memory, attention, social cognition and emotion recognition. Moreover, TS subjects are at significantly increased risk of developing attention deficit hyperactivity disorder (ADHD) and autism. At the neuroanatomical level, TS subjects display abnormalities across a number of brain structures, including the amygdala, hippocampus and orbitofrontal cortex. The TS phenotype arises due to reduced dosage of X-linked genes, and may also be modulated by parental origin of the single X chromosome. In this review, we discuss the utility of a mouse model of TS, the 39,XO mouse, in which the parental origin of the single X chromosome can be varied. This model provides the opportunity to investigate the effects of X-linked gene dosage/parent-of-origin effects on neurobiology in the absence of gross physiological abnormalities. Initial findings indicate that several features of the TS behavioural phenotype may be accurately recapitulated in the mouse. Furthermore, as X-linked gene dosage/imprinting can influence sex-specific neurobiology, investigations in the 39,XO mouse are also likely to offer insights into why certain neuropsychiatric disorders (including ADHD and autism) affect the sexes differently.

Le syndrome de Turner☆☆Cet article est publié en partenariat avec Orphanet et disponible sur le site www.orpha.net. © 2007 Orphanet. Publié par Elsevier Masson SAS. Tous droits réservés

Turner syndrome occurs in 1:5000 live births (1:2,500 females) and is caused not only by X-chromosome monosomy, but also in a large degree, by the presence of a mosaicism (45,X) and/or an abnormal X or Y chromosome (deletion, isochromosome X, dicentric chromosome). Clinical features are heterogeneous and typical physical anomalies are often mild or absent. In all cases, patients are short but final height has been improved by growth hormone therapy. Ovarian failure, with variable onset depending on the chromosomal anomalies, is frequent. Others visceral diseases (bone anomalies, lymphedema, deafness, and cardiovascular, thyroid, gastrointestinal diseases) are less common and need a screening at diagnosis, then a survey during adolescence and adulthood. During gestation, typical forms can be diagnosed by ultrasound examination, but mild forms are discovered incidentally during amniocentesis for unrelated reasons (advanced maternal age) and prenatal advice is difficult. The quality of life and social life is better when puberty is not induced too late, and in absence of cardiac disease or deafness. Deafness can lead to learning difficulties and, during adulthood, sterility can have a negative effect on quality of life. The prognosis depends on heart diseases, obesity, arterial hypertension and osteoporosis. Therefore, a long-term follow-up is necessary.

The development of mental state attributions in women with X-monosomy, and the role of monoamine oxidase B in the sociocognitive phenotype

We hypothesized that women with Turner syndrome (45,X) with a single X-chromosome inherited from their mother may show mentalizing deficits compared to women of normal karyotype with two X-chromosomes (46,X). Simple geometrical animation events (two triangles moving with apparent intention in relation to each other) which usually elicit mental-state descriptions in normally developing people, did not do so to the same extent in women with Turner syndrome. We then investigated the potential role in this deficit played by monoamine oxidase B enzymatic activity. MAO-B activity reflects central serotonergic activity, and by implication the functional integrity of neural circuits implicated in mentalizing. Platelet MAO-B was substantially reduced in Turner syndrome. However, contrary to prediction, in this (relatively small) sample there was no association between MAO-B enzymatic activity and mentalizing skills in participants with and without Turner syndrome.

Fetal testosterone and sex differences in typical social development and in autism

Experiments in animals leave no doubt that androgens, including testosterone, produced by the testes in fetal and/or neonatal life act on the brain to induce sex differences in neural structure and function. In human beings, there is evidence supporting a female superiority in the ability to read nonverbal signals, specific language-related skills, and theory of mind. Even more striking than the sex differences seen in the typical population is the elevated occurrence of social and communicative difficulties in human males. One such condition, autism, occurs four times more frequently in boys than in girls. Recently, a novel theory known as the "extreme male brain" has been proposed. It suggests that the behaviors seen in autism are an exaggeration of typical sex differences and that exposure to high levels of prenatal testosterone might be a risk factor. In this article, we argue that prenatal and neonatal testosterone exposures are strong candidates for having a causal role in sexual dimorphism in human behavior, including social development, and as risk factors for conditions characterized by social impairments, particularly autism spectrum conditions.

Turner syndrome: an update and review for the primary pediatrician

Turner syndrome (TS) is among the most common of the sex chromosomal aneuploidies. It results from the absence of one sex chromosome (or part of an X chromosome) in a female, leaving only one X chromosome present in the cell. Primary care physicians should be able to recognize the presenting signs and symptoms of TS, and once the diagnosis is confirmed by a chromosome analysis, they should be able to serve as a valuable source of support for the patient and her family and understand the most current treatments available.

Effects of Growth Hormone on Cognitive Function

Whether growth hormone deficiency (GHD) and/or treatment in childhood and adolescence influences cognitive outcome in children with GHD or girls with Turner syndrome (TS) is controversial. Previous studies also suggest that quality of life (QoL) is reduced in adults with GHD, particularly in the areas of social isolation and fatigue. Baseline QoL scores were significantly lower in patients with GHD than in the general population of the same age, gender, and nationality. Unfortunately, few data are available describing QoL in children with GHD. TS is a genetic disorder characterized by short stature, gonadal dysgenesis, and a particular neurocognitive profile of normally developed language abilities (particularly verbal intelligence quotients) and impaired visual-spatial and/or visual-perceptual abilities. This study evaluated the effects of GH treatment on neurocognitive function in girls with TS who were enrolled in a long-term, double-blind, placebo-controlled trial of the effects of GH treatment on final adult height. Treatment duration ranged from 1 to 7 years. The major result of this study was the absence of GH treatment effects on cognitive function in girls with TS. GHD and/or treatment in childhood and adulthood influences cognitive and/or QoL outcomes in some but not all studies. This study did not support a role for GH in influencing the characteristic nonverbal neurocognitive deficits associated with TS. However, evaluation of QoL should be a part of the routine clinical management of patients with GHD or TS.

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.

Amygdala and hippocampal volumes in Turner syndrome: a high-resolution MRI study of X-monosomy

Turner syndrome (TS) results from partial or complete X-monosomy and is characterized by deficits in visuospatial functioning as well as social cognition and memory. Neuroimaging studies have demonstrated volumetric differences in the parietal region of females with TS compared to controls. The present study examined amygdala and hippocampus morphology in an attempt to further understand the neural correlates of psychosocial and memory functioning in TS. Thirty females with TS age 7.6-33.3 years (mean = 14.7 +/- 6.4) and 29 age-matched controls (mean age = 14.8 +/- 5.9; range = 6.4-32.7) were scanned using high resolution MRI. Volumetric analyses of the MRI scans included whole brain segmentation and manual delineation of the amygdala and hippocampus. Compared to controls, participants with TS demonstrated significantly larger left amygdala gray matter volumes, irrespective of total cerebral tissue and age. Participants with TS also showed disproportionately reduced right hippocampal volumes, involving both gray and white matter. Amygdala and hippocampal volumes appear to be impacted by X-monosomy. Aberrant morphology in these regions may be related to the social cognition and memory deficits often experienced by individuals with TS. Further investigations of changes in medial temporal morphology associated with TS are warranted.

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.

Intonation abilities of children with speech and language impairments

Intonation has been little studied in children with speech and language impairments, although deficits in related aspects of prosody have been hypothesized to underlie specific language impairment. In this study a new intonation battery, the Profiling Elements of Prosodic Systems-Child version (PEPS-C), was administered to 18 children with speech and/or language impairments (LI). PEPS-C comprises 16 tasks (8 x 8, Input x Output) tapping phonetic and functional aspects of intonation in four areas: grammar, affect, interaction, and pragmatics. Scores were compared to a chronological age (CA) matched group of 28 children and a group of 18 children matched for language comprehension (LC). Measures of language comprehension, expressive language, nonverbal intelligence, and segmental phonology were also taken. The LI group did not score significantly below the LC group on any PEPS-C task. On 5 of 16 tasks, the LI group scored significantly lower than the CA group. In the LI group, there were just 2 significant correlations between a PEPS-C task and 1 of the nonprosodic measures. The results support the view that intonation is relatively discrete from other levels of speech and language while suggesting some specific areas of possible vulnerability: auditory memory for longer prosodic strings and the of prosody for pragmatic/interactional purposes.

Are you looking at me? Accuracy in processing line-of-sight in Turner syndrome

The behavioural phenotype of women with Turner syndrome (X-monosomy, 45,X) is poorly understood, but includes reports of some social development anomalies. With this in mind, accuracy of direction of gaze detection was investigated in women with Turner syndrome. Two simple experimental tasks were used to test the prediction that the ability to ascertain gaze direction from face photographs showing small lateral angular gaze deviations would be impaired in this syndrome, compared with a control population of men and women. The prediction was confirmed and was found to affect both the detection of egocentric gaze from the eyes ('is the face looking at me?') and the detection of allocentric gaze, where the eyes in a photographed face inspected one of a number of locations of attention ('where is she looking?'). We suggest that dosage-sensitive X-linked genes contribute to the development of gaze-monitoring abilities.

Cognitive and behavioral characteristics of turner syndrome: exploring a role for ovarian hormones in female sexual differentiation

To better understand factors contributing to behavioral development, we studied patients with Turner syndrome (TS), a disorder typically marked by prenatal onset of ovarian dysfunction. We compared girls and women (ages 12 and up) with TS (n = 21) to matched controls (n = 21) in cognitive and motor skills, as well as sex-typed personality characteristics and activity preferences. Measures were categorized (based on prior studies) as showing an average male advantage (male-superior measures), female advantage (female-superior measures), or no sex difference (sex-neutral measures). It was hypothesized that, if gonadal function contributes to behavioral development, effects of this deficiency would be more prominent on sexually differentiated than sex-neutral measures and thus that patient-control differences would be most marked for measures that show sex differences. Our findings indicated that TS patients and controls differed more on cognitive and motor domains that show sex differences than on sex-neutral domains. Patients also had more "undifferentiated" personalities and showed reduced sex-typed interests and activities. Differing experiences, as indexed by interests and activities, did not explain the observed cognitive and motor differences. These results are consistent with a role for ovarian hormones acting on the brain to influence cognitive and behavioral development, although they do not rule out other possible interpretations.

Persistent cognitive deficits in adult women with Turner syndrome

BACKGROUND

Turner syndrome (TS) has a characteristic neurocognitive profile. Verbal abilities are, in general, normal; however, women with TS, as a group, have specific deficits in visual-spatial abilities, visual-perceptual abilities, motor function, nonverbal memory, executive function, and attentional abilities. Observed deficits could be caused by genetic or endocrine factors.

OBJECTIVE

To evaluate the specific cognitive deficits that appear to persist in adulthood, are not estrogen-responsive, and may be genetically determined.

METHODS

The cognitive performance of adult women with TS (n = 71) who were estrogen repleted was compared with verbal IQ- and socioeconomic status-matched female controls (n = 50). Sixty-one women with TS had ovarian failure and received estrogen replacement and 10 had preserved endogenous ovarian function and were not receiving estrogen replacement at the time of evaluation.

RESULTS

Similar to children and adolescents with TS, adults with TS have normal verbal IQ but have relative difficulty on measures of spatial/perceptual skills, visual-motor integration, affect recognition, visual memory, attention, and executive function despite estrogen replacement. These deficits are apparent in women with TS despite apparently adequate estrogen effect, either endogenous or by hormone replacement.

CONCLUSION

The cognitive phenotypes of adults with TS, with or without ovarian failure, are similar, indicating that estrogen replacement does not have a major impact on the cognitive deficits of adults with TS.

Behavioral phenotypes of genetic syndromes: a reference guide for psychiatrists

OBJECTIVE

To review the literature on behavioral phenotypes of genetic syndromes, displaying the data as a reference guide for everyday practice.

METHOD

A computerized search was performed for articles published in the past 10 years, and selected papers were surveyed.

RESULTS

The behavioral phenotypes of 11 major genetic syndromes were reviewed including the following topics: genetic etiology, genetic counseling, physical features, medical problems, cognitive and behavioral profile, and psychopathology. The speculated correlation between the identified gene and the pathophysiology of the cognitive and behavioral features is discussed.

CONCLUSIONS

Updated knowledge of behavioral phenotypes will help psychiatrists identify these conditions, refer the patient and his/her family for genetic diagnosis and counseling, make specific treatment recommendations, and contribute to research and syndrome delineation.

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.

Neurobehavioral phenotype of Klinefelter syndrome

A defined genetic syndrome with neurobehavioral components offers an unusual paradigm for the correlation of genetic defects with neurodevelopmental abnormalities. The power of the combination of detailed behavioral, neuroanatomical, and genetic studies has been demonstrated in studies of other conditions involving the sex chromosomes, such as Fragile X syndrome (Mazzocco [2000] Ment Retard Develop Disabil Res Rev. 6:96-106) and Turner syndrome (Ross [2000] Ment Retard Develop Disabil Res Rev. 6:135-141). Although the behavioral and neurologic difficulties that have been identified in Klinefelter syndrome (KS) are in most cases milder than the consequences of many other genetic syndromes, the deficits in KS cause significant morbidity, representing a more common, but poorly understood, subtype of those with learning disabilities. Both as children and as adults, KS subjects appear to offer a powerful genetic model for the study of language and language-based learning disabilities. Although it has been proposed that the language-based learning difficulties of KS boys are similar to those of nonaneuploidic dyslexics [Bender et al., 1986; Geschwind et al., 1998], this is not yet well established. The co-morbid frontal-executive dysfunction observed in KS is also a likely contributor to learning difficulties and, perhaps, social cognition, in many KS patients. It is also proposed that altered left-hemisphere functioning, whether causing, or due to, altered functional and anatomical cerebral dominance, is at the core of KS subjects' language problems. Although X chromosomal loci can provide only part of the picture, the study of KS subjects, a population with a relatively homogeneous etiology for dyslexia/dysphasia and frontal-executive dysfunction, offers many advantages over such a study in the general population, in which both dyslexia and attentional disorders are quite genetically heterogeneous [Decker and Bender, 1988; Pennington, 1990; Grigorenko et al., 1997; Geschwind et al., 1998]. Furthermore, the interaction of genetic factors and hormonal influences in the cognitive phenotypes described remains an unexplored area for future investigation. MRDD Research Reviews 2000;6:117-124.

Distinctive patterns of memory function in subgroups of females with Turner syndrome: evidence for imprinted loci on the X-chromosome affecting neurodevelopment

X-monosomy is a form of Turner syndrome (TS) in which an entire X chromosome is missing. It is usually assumed that neuropsychological deficits in females with TS result from insufficient dosage of gene products from alleles on the sex chromosomes. If so, then parental origin of the single X chromosome should be immaterial. However, if there are imprinted genes on the X chromosome affecting brain development, neuropsychological development will depend on the parental origin of the single X chromosome. We contrasted verbal and visuospatial memory in females with a single paternal X chromosome (45,X(p)) and those with a single maternal X (45,X(m)). Neither group showed any impairment on immediate story recall; if anything, performance was above control levels. Groups did not differ on a measure of delayed recall. However, when delayed recall was considered after adjusting for level of immediate recall, 45,X(m) females showed enhanced verbal forgetting relative to controls over a delay. On the Rey figure, both groups were poor at copying the figure, but, after adjusting scores for initial copy score and strategy, only the 45,X(p) females showed disproportionate forgetting relative to controls. We propose there may be one or more imprinted genes on the X chromosome that affect the development of lateralised brain regions important for memory function.

Mental rotation: a task for the assessment of visuospatial skills of children

7 girls and 5 boys, ranging in age from 7 to 12 years, participated in the pilot testing of a mental rotation task developed for use in a comprehensive test battery of visuoperceptual abilities. Two asymmetric, three-dimensional objects were constructed from wood strips such that one object was the mirror-image of the other. Black and white photographs were taken of these objects in various spatial orientations along a horizontal plane. 16 photographs depicted the object right-side-up and in 16 the object was upside-down (rotated 180 degrees in the vertical plane). These photographs were presented to the children who were asked to match each with the corresponding object. Analysis indicated correct judgements of the right-side-up images occurred more frequently than the upside-down images (t11 = 4.73, p < .001). Using these data, adjustments were made to the task instructions to provide greater clarity for the young participants.

Discriminant analysis of the Ullrich-Turner syndrome neurocognitive profile

Ullrich-Turner syndrome (UTS), or monosomy X, is a genetic disorder characterized by short stature, gonadal dysgenesis, and a particular neurocognitive profile of normally developed language abilities (particularly verbal IQ) and impaired visual-spatial and/or visual-perceptual abilities. The most frequently described profile in UTS includes difficulty with tasks involving memory and attention, decreased arithmetic skills, and impaired visual spatial processing. We used discriminant function analysis (DFA) to distinguish between the neurocognitive profiles of girls with UTS vs. controls matched for age, height, IQ, and socioeconomic status. DFA is a statistical method for deriving a linear function that optimally weights parameters to permit sensitive and specific differentiation among groups. We developed a modified discriminant function, based on seven cognitive test scores, that successfully discriminated between the UTS and control subjects with a sensitivity of 0.45 and a specificity of 0.97. To validate its performance, we applied the discriminant function to a small group of 45,X UTS subjects (n = 13) and control female subjects (n = 25), ages 7-16 years, who were not part of the previous analyses. The discriminant function (DF) identified 54% of these 13 UTS subjects as having the "UTS neurocognitive profile" and 92% of the 25 control subjects as not having the profile. We also compared the DF scores of UTS girls with various mosaic karyotypes and found that the group with 46,XX mosaicism had significantly higher scores (i.e., closer to normal controls) than the other two mosaic groups (t = 2.86, P < 0.005). The results of this study should be useful for genetic counseling and planning educational programs for girls with UTS.