I thank Dr Atabek for his interesting comments about our study. He indicates that the definition proposed by the IDF for MS in children1 should be used, and that because the IDF did not consider it appropriate to diagnose MS in children aged younger than 10 years, our results are unclear. First, it should be noted that the new IDF statement was published on June 23, 2007, and our article was accepted for publication on June 6, 2007, readily explaining why these recommendations were not considered. Furthermore, the mean age of the group studied was 9 (SD, 2) years, but 42% of the children aged 10 years or older were prepubertal (Tanner stage 1). Thus, although most of the children were prepubertal, that does not mean that most of them were younger than 10 years. In our study,2 puberty was defined by Tanner stage, which is more accurate than age cutoffs that the IDF used to define puberty. For these reasons, we have reanalyzed our data using the definition proposed by the IDF for adolescents aged 10 to 16 years.