The frequency of uniparental disomy in Prader-Willi syndrome. - Mascari ,M.J.; Gottlieb ,W.; Rogan ,P.K.; Butler ,M.G.; Waller ,D.A.; Armour ,J.AL.; Jeffreys ,A.J.; Ladda ,R.L.; Nicholls ,R.D. (N Eng J Med, 1992)