Original article Beckwith–Wiedemann syndrome due to 11p15.5 paternal duplication associated with Klinefelter syndrome and a “de novo” pericentric inversion of chromosome Y Alicia Delicado a, *, Pablo Lapunzina a , María Palomares a , Maria Antonia Molina b , Enrique Galán c , Isidora López Pajares a a Department of Genetics, Hospital Universitario La Paz, Madrid, Spain b Department of Pediatrics, Endocrinology, Hospital Universitario La Paz, Madrid, Spain c Department of Genetics, Hospital Maternal de Badajoz, Badajoz, Spain Available online 01 February 2005 Abstract We report on an infant who had been prenatally diagnosed with Klinefelter syndrome associated with a “de novo” pericentric inversion of theY chromosome. A re-evaluation at 3 years of age sug- gested that he was also affected by Beckwith–Wiedemann syndrome (BWS). Karyotype was repeated and fluorescence in situ hybridisation (FISH) analysis revealed trisomy for 11p15.5→11pter and a distal monosomy 18q (18q23→qter). Parental cytogenetic studies showed that the father carried a balanced cryptic translocation between chromosomes 11p and 18q. Furthermore, the child had an extra X chromosome and a “de novo” structural abnormality of chromosomeY. Thus, his karyotype was 47,XX, inv (Y) (p11.2 q11.23), der(18) t (11;18) (p15.5;q23) pat. ish der(18) (D11S2071+, D18S1390–). Two markers on the X chromosome showed that the extra X of the child was paternally inherited. No deletions were observed on the structurally abnormal Y chromosome from any of the microsatellites studied. Clinical findings of patients with BWS due to partial trisomy 11p reveal that there is a distinct pattern of dysmorphic features associated with an increased incidence of mental retardation when comparing patients with normal chromosomes. This fact reinforces that FISH study have to be performed in all BWS patients, specially in those with mental retardation since small rearrangements cannot be detected by conventional cytogenetic techniques. © 2005 Elsevier SAS. All rights reserved. * Corresponding author. Servicio de Genética Médica, Hospital Universitario La Paz, Paseo de la Castellana 261, Madrid 28046, Spain. Tél. : +34 91 727 7217; Fax : +34 91 727 7050. E-mail address: adelicado.hulp@salud.madrid.org (A. Delicado). European Journal of Medical Genetics 48 (2005) 159–166 www.elsevier.com/locate/ejmg 1769-7212/$ - see front matter © 2005 Elsevier SAS. All rights reserved. doi:10.1016/j.ejmg.2005.01.017