Article Title: 48,XXYY, 48,XXXY and 49,XXXXY syndromes: not just variants of Klinefelter syndrome
Authors: Tartaglia, Ayari, Howell, D’Epagnier, Zeitler
Date of Publication: April 9, 2011
“Sex chromosome tetrasomy and pentasomy conditions occur in 1:18,000-1:100,000 male births. While often compared with 47,XXY/Klinefelter syndrome because of shared features including tall stature and hypergonadotropic hypogonadism, 48,XXYY, 48,XXXY and 49,XXXXY syndromes are associated with additional physical findings, congenital malformations, medical problems and psychological features.”