Different clinical presentation of Klinefelter's syndrome in monozygotic twins

• Published in: Andrologia Vol. 47; no. 1; pp. 116 - 120
• Main Authors: Benaiges, D., Pedro‐Botet, J., Hernández, E., Tarragón, S., Chillarón, J. J., Flores Le‐Roux, J. A.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01-02-2015
• Subjects: Androgens; Diseases in Twins; homozygotic twins; Humans; Klinefelter Syndrome - diagnosis; Klinefelter Syndrome - genetics; Klinefelter Syndrome - physiopathology; Klinefelter's syndrome; Language disorders; Male; male hypogonadism; Men; Middle Aged; Mosaicism; Twins, Monozygotic; Klinefelter's syndrome; homozygotic twins; male hypogonadism
• ISSN: 0303-4569; 1439-0272
• DOI: 10.1111/and.12219

Summary
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.