About Open Access
Discordance for X-Linked Hypophosphataemic Rickets in Identical Twin Girls
Lookup NU author(s)
Dr Kate Owen
Professor Simon Pearce
Dr Michael Wright
Dr Timothy Cheetham
Owen CJ, Habeb A, Pearce SH, Wright M, Ichikawa S, Sorenson AH, Econs MJ, Cheetham TD
Full text for this publication is not currently held within this repository. Alternative links are provided below where available.
Background: 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. Methods: 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 PHEX and FGF23 genes were sequenced. Results: 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 1.15-2.58 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 PHEX and FGF23 genes was normal. Conclusions: Discordant X inactivation is a well-recognised phenomenon in identical twins, and we suspect that non-random expression of the normal PHEX gene in critical tissues is the most likely explanation for non-penetrance.
S. Karger AG
Altmetrics provided by
Newcastle University Library, NE2 4HQ, United Kingdom. Tel: 0044 (191) 208 2920
©2017 Newcastle University Library