{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,9]],"date-time":"2026-07-09T23:45:24Z","timestamp":1783640724043,"version":"3.55.0"},"reference-count":28,"publisher":"S. Karger AG","issue":"4","license":[{"start":{"date-parts":[[2009,1,1]],"date-time":"2009-01-01T00:00:00Z","timestamp":1230768000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/www.karger.com\/Services\/SiteLicenses"},{"start":{"date-parts":[[2009,1,1]],"date-time":"2009-01-01T00:00:00Z","timestamp":1230768000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/www.karger.com\/Services\/SiteLicenses"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Horm Res Paediatr"],"published-print":{"date-parts":[[2009]]},"abstract":"<i>Background:<\/i> We report monozygotic twin girls with a family history consistent with X-linked hypophosphataemic rickets (XLH). One twin had a skeletal and biochemical phenotype consistent with XLH, whilst the second twin appeared normal. Complete non-penetrance in XLH has not been previously reported and our aim was to explore potential reasons for this. <i>Methods:<\/i> Serum and urine biochemistry were analysed at regular intervals. Microsatellite analysis was performed to confirm monozygosity and bi-parental inheritance of the X chromosome. The X chromosome inactivation pattern was studied in peripheral blood. Exons of the paternal <i>PHEX<\/i> and <i>FGF23<\/i> genes were sequenced. <i>Results:<\/i> Biochemistry was persistently abnormal in the slow-growing twin 1 and normal in twin 2 who has grown normally. Maximal tubular phosphate reabsorption was 0.68 mmol\/l in twin 1 and 1.64 mmol\/l in twin 2 at 10.8 years of age (normal 1.15\u20132.58 mmol\/l). Microsatellite analysis confirmed monozygosity and the X chromosome inactivation pattern was random. These studies also excluded uniparental isodisomy. The exon sequence of paternal <i>PHEX<\/i> and <i>FGF23<\/i> genes was normal. <i>Conclusions:<\/i> Discordant X inactivation is a well-recognised phenomenon in identical twins, and we suspect that non-random expression of the normal <i>PHEX<\/i> gene in critical tissues is the most likely explanation for non-penetrance.<\/jats:p>","DOI":"10.1159\/000201113","type":"journal-article","created":{"date-parts":[[2009,3,4]],"date-time":"2009-03-04T11:05:48Z","timestamp":1236164748000},"page":"237-244","source":"Crossref","is-referenced-by-count":8,"title":["Discordance for X-Linked Hypophosphataemic Rickets in Identical Twin Girls"],"prefix":"10.1159","volume":"71","author":[{"given":"Catherine J.","family":"Owen","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Abdul","family":"Habeb","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Simon H.S.","family":"Pearce","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael","family":"Wright","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shoji","family":"Ichikawa","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andrea H.","family":"Sorenson","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael J.","family":"Econs","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tim D.","family":"Cheetham","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"127","published-online":{"date-parts":[[2009,3,4]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","DOI":"10.1016%2FS0031-3955%2805%2970485-5"},{"key":"ref2","doi-asserted-by":"publisher","DOI":"10.1038%2Fng1095-130"},{"key":"ref3","doi-asserted-by":"publisher","DOI":"10.1086%2F499409"},{"key":"ref4","doi-asserted-by":"publisher","DOI":"10.1086%2F499410"},{"key":"ref5","doi-asserted-by":"publisher","DOI":"10.1210%2Fjc.82.2.674"},{"key":"ref6","doi-asserted-by":"publisher","DOI":"10.1038%2F81664"},{"key":"ref7","doi-asserted-by":"publisher","DOI":"10.1210%2Fjc.86.2.494"},{"key":"ref8","doi-asserted-by":"publisher","DOI":"10.1074%2Fjbc.M304544200"},{"key":"ref9","doi-asserted-by":"publisher","DOI":"10.1172%2FJCI200318563"},{"key":"ref10","doi-asserted-by":"publisher","DOI":"10.1016%2Fj.bone.2003.10.005"},{"key":"ref11","doi-asserted-by":"publisher","DOI":"10.1210%2Fjc.86.8.3889"},{"key":"ref12","doi-asserted-by":"publisher","DOI":"10.1007%2FBF00862587"},{"key":"ref13","doi-asserted-by":"publisher","DOI":"10.1016%2FS0140-6736%2875%2992736-1"},{"key":"ref14","doi-asserted-by":"publisher","DOI":"10.1136%2Fadc.65.11.1208"},{"key":"ref15","doi-asserted-by":"publisher","DOI":"10.1016%2FS0024-3205%2897%2900686-3"},{"key":"ref16","doi-asserted-by":"publisher","DOI":"10.1210%2Fjc.83.10.3615"},{"key":"ref17","doi-asserted-by":"publisher","DOI":"10.1210%2Fjc.86.8.3840"},{"key":"ref18","doi-asserted-by":"publisher","DOI":"10.1210%2Fjc.81.11.4075"},{"key":"ref19","doi-asserted-by":"publisher","DOI":"10.1097%2F00005792-198911000-00002"},{"key":"ref20","doi-asserted-by":"publisher","DOI":"10.1136%2Fjmg.33.8.700"},{"key":"ref21","doi-asserted-by":"publisher","DOI":"10.1136%2Fjmg.23.6.494"},{"key":"ref22","doi-asserted-by":"publisher","DOI":"10.1136%2Fjmg.37.8.603"},{"key":"ref23","doi-asserted-by":"publisher","DOI":"10.1182%2Fblood-2002-01-0277"},{"key":"ref24","doi-asserted-by":"publisher","DOI":"10.1016%2Fj.ymgme.2004.11.009"},{"key":"ref25","doi-asserted-by":"publisher","DOI":"10.1086%2F301988"},{"key":"ref26","doi-asserted-by":"publisher","DOI":"10.1086%2F301978"},{"key":"ref27","doi-asserted-by":"publisher","DOI":"10.1002%2F%28SICI%291097-0223%28199803%2918%3A3%3C201%3A%3AAID-PD245%3E3.0.CO%3B2-W"},{"key":"ref28","doi-asserted-by":"publisher","DOI":"10.1038%2Fng0796-290"}],"container-title":["Hormone 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