A population-based approach to the investigation of osteopenia in Rett syndrome

This study compares bone mass in a national sample of girls with Rett syndrome (RS) with a sample of control children. The Australian RS Database was the source of cases for this population-based study. Hand radiographs were available from 101 of 137 subjects (74% of the known Australian population of girls with RS aged [les ]20 years). Control radiographs matched for age, sex, and laterality were obtained from hospital radiology departments. A measure of cortical thickness was made from the difference between the outer diameter and the medullary space in the second metacarpal bone. A mean z-score value for cortical thickness and percentage cortical area for each individual was calculated. The mean cortical thickness (z score) for girls with RS was −1.94 compared with −0.38 for control children (P