DISCORDANT PUBERTY IN MONOZYGOTIC TWIN SISTERS WITH NEUROFIBROMATOSISTYPE-1 (NF1)

Monozygotic twin sisters are reported who have discordant pubertal gro wth and sexual development. Although both sisters were physiologically appropriate for chronological age in their pubertal development, thei r adolescent development was considerably different from that expected of monozygotic twin sisters. The more pubertally advanced sister by m agnetic resonance imaging had an optic pathway glioma while none was p resent in her twin sister, Precocious puberty is not an unexpected com plication of neurofibromatosis type 1 and is always associated with th e presence of an optic pathway glioma. These sisters emphasize the str iking similarity that is expected of monozygotic twins and the need fo r investigation when intertwin differences in growth and/or developmen t arise.