Absence of the second X chromosome in Turner syndrome is generally well tolerated, but in cases of small fragments or rings derived from the X chromosome, the incidence of mental retardation and other unusual congenital abnormalities can be significantly higher. This investigation focuses on a 9-year-old female who was referred for molecular analysis of the karyotype because of dysmorphic features uncharacteristic of Turner's syndrome such as moderate psychomotor retardation, significant language delay and autism. Karyotype analysis by Affymetrix CytoScan™ high-density (HD) array allowed to identify a small fragment derived from the X chromosome which was detected in 70% of cells. The fragment appeared to be made mainly of alphoid sequences with breakpoints in the juxtacentromeric region Xp11.1 and Xq13.2. The fragment did not include the XIST locus and might not, therefore, be subject to X-inactivation. Interestingly we also detected a 15q13.3 microdeletion of 1.84 Mb, including the genes: FAN1, TRPM1, MIR211, KLF13, OTUD7A, CHRNA7 and ARHGAP11A. The 15q13.3 microdeletion syndrome (OMIM#612001) is characterized by a wide range of phenotypic features, including intellectual disability, autism and psychiatric conditions.