 We report on the use of fluorescence in situ hybridization (FISH) with specific chromosome 8 arm painting to characterize further small supernumerary chromosome 8-derived markers/rings (SMC/SRC) identified in three patients.     ///    "The identification of the SMC/SRC was first characterized by FISH specific alpha-repeat centromeric probes, second by FISH whole chromosome painting (WCP), and finally by FISH chromosome arm painting (CAP). "    ///    "The latter showed involvement of only the short arm of chromosome 8 in all three SMC/SRC cases, suggesting a U-type exchange mechanism.. "