Cytogenet Cell Genêt 74:293-294 (1996) Cytogenetics and CellGenetics Assignaient* of thé gène for methyl-CpG-binding protein 2 (MECP2) to human chromosome band Xq28 by in situ hybridîzation A. Vilain, F. Apiou, N. Vogt, B. Dutrillaux, and B. Malfoy Institut Curie-CNRS UMR 147, Paris (France) Rationale and significance The biological functions of methylated DNA are thought to be mediated by methylation sensitive DNA binding proteins. Several proteins that specifically bind methylated DNA hâve been characterized (reviewed in Tate and Bird, 1993). In murine cells, thé methyl-CpG-binding protein 2 (MeCP2) is an abundant chromosomal protein, mostly concentrated in thé centromeric heterochromatin but also présent throughout chro- mosome arms (Lewis et al., 1992). MeCP2 is essential for embryonic development but dispensable for cells growing in vitro (Tate et al., 1996). Using interspecific backcross panels, thé mouse gène has been localized to thé X chromosome between thé Llcam and thé Rsvp loci (Quaderi et al., 1994). Materials and methods FISH was performed as described (Apiou et al., 1996). Metaphase chro- mosome préparations were made from human normal lymphocytes after BrdU incorporation. Direct R-banding of BrdU substituted chromosomes was obtained by incubation in an alkaline solution of p-phenylenediamine and staining with propidium iodide. Immunochemical détection of thé bio- tin-labeled probe was performed using mouse antibiotin antibodies (Dako) and goat Rhodol green-conjugated anti-mouse IgG antibodies (Molecular Probe). Probe name: hmecp2EG5 Probe type: cDNA Insert size: 1.5 kb Vector: pZErO-2 Fig. 1. In situ hybridization on R-banded chromosomes of thé biotin-labeled MECP2 1.5- kb cDNA probe at Xq28. The metaphase chromo- some images, acquired using Ektachrome 400 ASA film (Kodak), were processed with thé Ad- obe Photoshop software. Gène référence and proof of authenticity: thé complète human MECP2 coding région has been obtained by RT-PCR using oligonucleotides selected from thé rat séquence (Lewis et al., 1992). The séquences of thé cDNA and of thé second intron of thé gène hâve been deposited with thé GeneBank/EMBL Data Libraries (Accession Nos: X99686, X99687). The human and rat gènes showed an overall identity of 88 % and 94 % at thé nucleotide and amino acid level, respectively. * To our knowledge this is thé f irst time this gène hasbeen mapped. Supported by grants from thé Association pour la Recherche sur le Cancer and thé Ligue Nationale contre le Cancer (Comité National et Paris). A.V. is a fellow from thé Ligue contre le Cancer (Comité Oise). Received 9 August 1996; manuscript accepted 12 August 1996. Request reprints from B. Malfoy, Institut Curie, 26 rue d'Ulm, 752311 Paris Cedex 05 (France); téléphone: 33 142 34 66 85; fax: 33 1 42 3466 74; e-mail: bmalfoy@curie.fr Results Mappingdata Location: Xq28 No. of cells examined: 32 Number of cells with spécifie signal: 25 1 (12), 2 (9), 3 (2), 4 (2) chromatids per cell Most précise assignment: Xq28 Location ofbackgroundsignais (sites with >2 signais): None observed E-mail kargcr@karger.ch Fax + 416 i3061234 http://www. karger. ch © 1996 S. Karger AG, Basel 0301-0171/96/0744-0293$ 10.00/0