title: Different clinical presentation of Klinefelter's syndrome in monozygotic twins.
abstract: There is a wide variability in the clinical presentation of Klinefelter's syndrome. We report the case of a 45-year-old man who was incidentally diagnosed a 47,XXY/46,XY karyotype in a bone marrow aspiration (case 1). He presented hypogonadic features with undetectable testosterone levels and a height in accordance with mid-parental height. He had a monozygous sibling (case 2) who did not show clinical signs of hypogonadism and whose height exceeded mid-parental height. Both patients had presented language disorders since childhood. The karyotype of lymphocytes in peripheral blood of both subjects was compatible with mosaic Klinefelter's syndrome (46,XY/47,XXY). Testosterone replacement was initiated in case 1. Lack of testicular involvement due to mosaicism and the overexpression of the SHOX gene in case 2 could explain the marked differences in phenotype in these homozygous twins.
authors.affiliation: Department of Endocrinology and Nutrition, Hospital del Mar, Barcelona, Spain; Department of Internal Medicine, Hospital Comarcal de l'Alt Penedés, Barcelona, Spain; Department of Medicine, Universitat Autònoma de Barcelona, Barcelona, Spain; IMIM (Institut Hospital del Mar d'Investigacions Mèdiques), Barcelona, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Benaiges
authors.forename: J
authors.initials: J
authors.lastname: Pedro-Botet
authors.forename: E
authors.initials: E
authors.lastname: Hernández
authors.forename: S
authors.initials: S
authors.lastname: Tarragón
authors.forename: J J
authors.initials: JJ
authors.lastname: Chillarón
authors.forename: J A
authors.initials: JA
authors.lastname: Flores Le-Roux
mesh_terms: D004200:Diseases in Twins; D006801:Humans; D007713:Klinefelter Syndrome / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009030:Mosaicism; D014430:Twins, Monozygotic
keywords: Klinefelter's syndrome; homozygotic twins; male hypogonadism