To date, no comprehensive genotype–phenotype association studies have been conducted in regard to the genes involved in the Xq duplication involving MECP2. The minimally duplicated region in MDS includes the MECP2 and IRAK1 genes [4, 14, 19, 25, 28, 30, 40, 42, 44, 49, 52, 58, 112], and individuals with a larger, cytogenetically visible Xq28 duplication have been reported to display characteristics such as microcephaly, pre- and post-natal growth deficiency, inguinal hernia, palate clefting and hypoplastic genitalia [11]. This evidence concerns the gene MECP2 and Growth delay.