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.
"In a review paper, Savic reported that the behavioral phenotype of Klinefelter syndrome is characterized by language, executive and psychomotor dysfunction, as well as socioemotional impairment. The prevalence of schizophrenia, attention deficit hyperactivity disorder, ASD and affective regulation problems in patients with Klinefelter syndrome also increased [Savic, 2012]. "
"Early studies described boys with XXY as timid, aggressive , disruptive, and as having low self-esteem and social immaturity [Bancroft et al., 1982; Mandoki and Sumner, 1991]. Social anxiety, ADHD, social communication, and atypical peer interactions comprise some of the features of XXY newly described [Ross et al., 2005; Bishop et al., 2010; van Rijn et al., 2011; Savic, 2012; Stochholm et al., 2012; Tartaglia et al., 2012]. ADHD has been reported as a major behavioral deficit in boys with 47,XXY with an incidence ranging from 34% to 63% [Giedd et al., 2007; Bruining et al., 2010; Ross et al., 2012; Tartaglia et al., 2012]. "
[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.
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