Dental maturity is advanced in fragile X syndrome

Fragile X (FraX) syndrome is the most common cause of inherited mental reta rdation. The FraX gene (FMR1) has been cloned, and the mutation causing the disease is now known. We estimated the effect of FraX on dental developmen t in 28 affected boys (aged 4.9-17.6 years) and three carrier girls (aged 5 .8, 10.4, and 12.7 years), Dental maturity, assessed on the basis of format ion [Demirjian A, Goldstein H. 1976: Am Hum. Biol 3:411-421] and of emergen ce [Hagg U, Taranger J. 1985: Angle Orthod 55:93-107], was compared with gr owth in stature and skeletal maturity, The mean relative dental age was adv anced in FraX males, based on formation (+1.4 SD) and on emergence (+1.1 SD ). More pronounced advancement was seen in younger children, Dental maturit y was advanced in heterozygous carrier girls as well. Height and skeletal m aturity did not show a similar trend toward advanced development. (C) 1999 Wiley-Liss, Inc.