American Journal of Medical Genetics 113:263–267 (2002) Identification of a Neocentromere in a Rearranged Y Chromosome With No Detectable DYZ3 Centromeric Sequence Juliana Godoy Assumpc ¸a ˜ o, 1 Windy Berkofsky-Fessler, 2 Nilma Viguetti Campos, 3 Andre ´ a Trevas Maciel-Guerra, 3 Shulan Li, 2 Maria Isabel Melaragno, 4 Maricilda Palandi de Mello, 1 and Peter E. Warburton 2 * 1 Centro de Biologia Molecular e Engenharia Gene´tica, Universidade Estadual de Campinas, Campinas, SP, Brasil 2 Department of Human Genetics, Mount Sinai School of Medicine, New York, New York 3 Departamento Gene´tica Me´dica, Faculdade deCie ´ncias Me´dicas, Universidade Estadual deCampinas, Campinas, SP, Brasil 4 Disciplina de Gene´tica, Departamento de Morfologia, UNIFESP/EPM, Sa ˜ o Paulo, SP, Brasil An 18-year-old woman was evaluated be- cause of primary amenorrhea and hypo- gonadism. Chromosome analysis from peripheral blood lymphocytes revealed a nonmosaic 46,X,þmar constitution. The mar- ker was shown to be a rearranged Y chromo- some consisting of an inverted duplication of the long arm: rea(Y)(qter-q11::q11-qter). Deletion mapping analysis with Y-specific STS showed that the marker lacked Yp and Y-centromeric (DYZ3) sequences, but it was positive for Yq sequences tested. Fluores- cence in situ hybridization analysis with Y and X chromosome centromeric and pancen- tromeric probes showed no hybridization signals. The marker chromosome is present in 100% of the cells; therefore, it is mitotically stable despite the absence of DYZ3 centro- meric sequence. Hybridization with CENP-A and CENP-C specific antibodies localized a neocentromere close to the breakpoint. ß 2002 Wiley-Liss, Inc. KEY WORDS: chromosomal abnormalities; chromosomal structure/func- tion; clinical cytogenetics; FISH; neocentromere INTRODUCTION In eukaryotes, the centromere, cytogenetically defin- ed as the primary constriction, is the site of sister chromatid attachment. It is essential for proper segre- gation of the chromosomes during mitosis and meiosis [Pluta et al., 1995]. The mammalian centromere con- tains large amounts of highly repeated satellite DNA, the best characterized of which is alpha-satellite DNA [Manuelidis, 1978]. Alpha-satellite DNA is believed to be important for centromeric function because it is the only type of sequence shown to be present at the primary constric- tion of all human chromosomes [Manuelidis, 1978]. The introduction of artificial chromosomes carrying alpha- satellite DNA into mammalian cells has demonstrat- ed that this DNA sequence provides some, if not all, information required in cis for the formation of the cen- tromere [Haff et al., 1992; Larin et al., 1994; Harrington et al., 1997, Ikeno et al., 1998]. Conflicting evidence for alphoid satellite as an essen- tial DNA component of functional centromeres has emerged from the study of stable marker chromosomes, which fail to show labeling with specific alpha-satellite DNA probes. These analphoid chromosomes carry newly derived centromeres (called ‘‘neocentromeres’’) that are apparently formed within interstitial chromosomal sites that have not previously been known to express centromere function [Choo, 1997; du Sart et al., 1997; Warburton et al., 2000]. Moreover, in human dicentric chromosomes, the alpha-satellite DNA is present on both the active and inactive centromeres, suggesting that the presence of alpha satellite per se is insufficient to determine centromere function [Earnshaw et al., 1989; Warburton, 2001]. Five constitutive centromere-binding proteins have been implicated in centromere function: CENP-A, CENP-B, CENP-C, CENP-G and CENP-H. Three of them (CENP-A, -C and -H) associate specifically with active centromeres, that is, are present on normal Grant sponsor: Conselho Nacional de Pesquisa e Desenvolvi- mento (CNPq); Grant sponsor: National Institutes of Health; Grant numbers: R01, GM61150. *Correspondence to: Dr. Peter E. Warburton, Department of Human Genetics, Box 1498, Mount Sinai School of Medicine, 1425 Madison Avenue, East Building 14-52A, New York, NY 10029. E-mail: peter.warburton@mssm.edu Received 14 November 2001; Accepted 28 April 2002 DOI 10.1002/ajmg.10701 ß 2002 Wiley-Liss, Inc.