Article

Advances in research on the neurological and neuropsychiatric phenotype of Klinefelter syndrome.

Department of Clinical Neuroscience, Karolinska Institute, Solna, Stockholm, Sweden.
Current opinion in neurology (Impact Factor: 5.43). 04/2012; 25(2):138-43. DOI: 10.1097/WCO.0b013e32835181a0
Source: PubMed

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.

0 Bookmarks
 · 
101 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The Klinefelter syndrome (KS), with an incidence of 1 to 2 per 1000 male neonates, is one of the most frequent congenital chromosome disorders. The 47,XXY karyotype causes infertility, testosterone deficiency and a spectrum of further symptoms and comorbidities. In recent years, significant progress has been made in the elucidation of the pathophysiology and the treatment of the KS. It became clear that, to a large extent, the clinical picture is determined by gene dosage effects of the supernumerary X-chromosome. The origin of the extra X-chromosome from either the father or the mother influences behavioural features of patients with KS. The CAGn polymorphism of the androgen receptor, located on the X-chromosome, has a distinct impact on the KS phenotype. KS predisposes to the metabolic syndrome and its cardiovascular sequelae, contributing to the increased mortality of patients with KS. Neuroimaging studies have correlated anomalies in brain structures with psychosocial problems. The unexpected possibility to produce pregnancies and live birth with either ejaculated sperm - about 8% of KS men have a few sperm in semen - or with sperm extracted from individual tubules obtained by testicular biopsy can be considered a breakthrough. Testosterone substitution requires further optimisation in terms of when to initiate therapy and which preparations and dosages to use. Recently developed animal models help to further elucidation the genetic and pathopysiological basis and may lead to new therapeutic approaches to KS.
    Annales d Endocrinologie 04/2014; · 1.02 Impact Factor
  • Source
    [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. · 3.23 Impact Factor
  • [Show abstract] [Hide abstract]
    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; · 1.41 Impact Factor