A 10.5-year-old girl, referred for genetic evaluation because of short stature, had a karyotype 45,X [30%]/ 46,X, idic(X)(qter_p12.3::p12.3_qter) [70%]. Whole chromosome painting revealed homogeneous painting of the abnormal X chromosome. Fluorescent in situ hybrid­ization (FISH) studies with a satellite X (DXZ1), Xp/Yp telomeres and the Short stature homebox (SHOX) probe showed one hybridization signal for each probe used on the normal X chromosome. On the abnormal idic (X) chro­mosome, two centromeres were displayed with DXZ1 and there were no signals for the telomeres Xp/Yp and the SHOX gene. Polymerase chain reaction (PCR) amplifica­tion of polymorphic regions on the X chromosome (DYSI, DYSII, NM, STR44, STR45, STR49, STR50 and STRHI loci of the dystrophin gene on Xp21.1, CGG region of FMR-1 gene and regions DXS548 and FRAXAC2 on Xq and CAG repeat of the androgen receptor gene on Xq11.2-12) was performed to determine the missing regions and parental origin of the abnormal idic (X) chromosome. The analysis produced little information for most of the loci examined. Nevertheless, the findings indicate that the idic (X) chromosome is most likely of maternal origin and that the breakpoints on the Xps were distal to the DMD gene.