Advances in research on the neurological and neuropsychiatric phenotype of Klinefelter syndrome.
ABSTRACT Klinefelter syndrome, 47,XXY is the most common chromosomal aberration among men. It represents a naturally occurring human model for studies of both X-chromosome gene expression and potential androgen effects on brain development and function. The aim of this review is to combine available brain imaging and behavioral data to provide an overview of what we have learned about the neural underpinnings of cognitive, emotional and behavioral dysunctions in Klinefelter syndrome.
The behavioral phenotype of 47,XXY is characterized by language, executive and psychomotor dysfunction, as well as socioemotional impairment. The prevalence of schizophrenia, attention deficit hyperactivity disorder, autism spectrum disorders and affective regulation problems is increased. Neuroimaging studies of children and adults with Klinefelter syndrome syndrome show characteristic structural changes from typical individuals. There are increases in the grey matter volume of the sensorimotor and parietooccipital regions, as well as significant reductions in amygdala, hippocampal, insular, temporal and inferior-frontal grey matter volumes. Widespread white matter abnormalities have been revealed, with reductions in some areas (including anterior cingulate, bilaterally) but increases in others (such as left parietal lobe). Mechanisms underlying these developmental anomalies could include imbalance in gene dosage relative to typical men or women, as well as the potential consequence of endocrinological deficits.
Studies of Klinefelter syndrome could generate important information about the impact of anomalies in sex chromosome gene regulation on the development of cerebral grey and white matter and, ultimately, on human behavior.
- SourceAvailable from: Hsiao-Mei Liao[Show abstract] [Hide abstract]
ABSTRACT: Autism spectrum disorders (ASD) are childhood-onset neurodevelopmental disorders characterized by verbal communication impairments, social reciprocity deficits, and the presence of restricted interests and stereotyped behaviors. Genetic factors contribute to the incidence of ASD evidently. However, the genetic spectrum of ASD is highly heterogeneous. Chromosomal abnormalities contribute significantly to the genetic deficits of syndromic and non-syndromic ASD. In this study, we conducted karyotyping analysis in a sample of 500 patients (447 males, 53 females) with ASD from Taiwan, the largest cohort in Asia, to the best of our knowledge. We found three patients having sex chromosome aneuploidy, including two cases of 47, XXY and one case of 47, XYY. In addition, we detected a novel reciprocal chromosomal translocation between long arms of chromosomes 4 and 14, designated t(4;14)(q31.3;q24.1), in a patient with Asperger's disorder. This translocation was inherited from his unaffected father, suggesting it might not be pathogenic or it needs further hits to become pathogenic. In line with other studies, our study revealed that subjects with sex chromosomal aneuploidy are liable to neurodevelopmental disorders, including ASD, and conventional karyotyping analysis is still a useful tool in detecting chromosomal translocation in patients with ASD, given that array-based comparative genomic hybridization technology can provide better resolution in detecting copy number variations of genomic DNA. © 2013 Wiley Periodicals, Inc.American Journal of Medical Genetics Part B Neuropsychiatric Genetics 10/2013; 162(7):734-41. DOI:10.1002/ajmg.b.32153
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ABSTRACT: The behavioral phenotype of children with XXY has not been extensively studied until recently and this research has been confounded by insufficient study populations and ascertainment biases. The aim of the study was to expand the behavioral aspect of the XXY phenotype as well as investigate the role of existing familial learning disabilities (FLD) on behavioral problems. Behavioral phenotype of XXY includes social anxiety, ADHD, social communication, and atypical peer interactions. The Child Behavior Checklist (CBCL), Social Responsiveness Scale (SRS), and Gilliam Autism Rating Scale (GARS) were completed by the parents of 54 boys with XXY who had not received hormonal replacement prior to participation. Our findings suggest fewer behavioral deficits and lower severity in the general 47,XXY population than previously published and found significant differences between the groups with a positive FLD on the behavioral assessments. Findings demonstrate that boys with FLD exhibit an increased incidence and severity of behavioral problems. Our study expands on the findings of Samango-Sprouse et al. [Samango-Sprouse et al. (2012b) J Intellect Disabil Res] and the significant influence that FLD has on not only neurodevelopment, but also behavioral deficits. Our study suggests that part of the XXY phenotypic profile may be modulated by FLD. Further study is underway to examine the interaction between the many salient factors effecting behavioral and neurodevelopmental progression in XXY and variant forms. © 2013 Wiley Periodicals, Inc.American Journal of Medical Genetics Part C Seminars in Medical Genetics 02/2013; 163(1):27-34. DOI:10.1002/ajmg.c.31353
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ABSTRACT: Affected patients with hypogonadism have unnaturally low amounts of sex hormones that produce male and female sex characteristics. Males who suffer from this condition lack testosterone, while females fail to produce enough estrogen. Hypogonadism may be present at birth, or it may take effect years later following injury or illness to the sex glands. Hypogonadism has remarkable associations with variable medical disorders; however, it is characterized by a distinctive association with variable neurological disorders: such as epilepsy, ataxia, dysmyelination, nerve muscle disease, movement disorders, mental retardation and deafness. The remarkable neurological diseases with hypogonadism should not basically be regarded as coincidental findings, but possibly related to an intrinsic pathophysiological association.Neurological Sciences 01/2013; 34(5). DOI:10.1007/s10072-012-1278-4