{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,7,16]],"date-time":"2025-07-16T13:13:34Z","timestamp":1752671614855,"version":"3.40.4"},"reference-count":21,"publisher":"BMJ","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["BMJ Case Reports"],"abstract":"<jats:p>Klinefelter\u2019s syndrome (KS; karyotype 47,XXY) is associated with specific neurocognitive impairments, especially delayed language development and impaired socioemotional evolution. There is an increased risk for psychiatric disturbances, particularly schizophrenia and affective spectrum disorders.<\/jats:p><jats:p>A 51-year-old monozygotic male twin with KS is described of whom one was referred for long-lasting paranoid psychotic symptoms. Both were treated with testosterone and had an average level of intelligence. Detailed psychiatric and neuropsychological assessment in the referred patient demonstrated quasi-psychotic symptoms with illusions, delusion-like ideas, paranoid ideation, magical thinking, circumstantial speech and thinking and eccentric behaviours. In addition, attentional deficits and executive dysfunctions could be demonstrated. A diagnosis of schizotypal personality disorder was made. A less pronounced identical clinical picture was found in his brother. The psychopathological phenotype of KS is characterised by a schizotypal personality which originates from its specific cognitive defects and that, with increasing age, may develop into a schizophrenia-like psychosis.<\/jats:p>","DOI":"10.1136\/bcr.05.2011.4279","type":"journal-article","created":{"date-parts":[[2011,7,29]],"date-time":"2011-07-29T15:13:53Z","timestamp":1311952433000},"page":"bcr0520114279","source":"Crossref","is-referenced-by-count":3,"title":["Schizotypy: key feature of Klinefelter\u2019s syndrome?"],"prefix":"10.1136","volume":"2011","author":[{"given":"Willem M A","family":"Verhoeven","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jos I 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