The concept of anomalous cerebral lateralization in Klinefelter syndrome

Klinefelter syndrome (KS) is a genetic disorder in males characterized by the presence of an extra X chromosome. Its most consistent endocrinological manifestations include lower testosterone production and impaired spermatogenesis. KS individuals have a general typical appearance with taller stature, and they demonstrate a characteristic cognitive phenotype involving weaknesses in verbal processing. Anomalous cerebral lateralization involves the inverse or weak dominance of hand, language, and visuospatial abilities and has been associated with the cognitive deficits of KS individuals. This article summarizes the ongoing research in this field, discusses the main findings, and attempts to provide a thorough description of the cause of the observed functional and anatomical cerebral asymmetries associated with the syndrome. Nonetheless, efforts have been directed to incorporate evidence for and against theoretical accounts that explain the experimental findings, to discuss issues involving the implications of the chosen methodology, and present key research areas for future empirical research.