Identification of a complex translocation involving chromosomes 3, 18 and 21. A: Pedigree of the proband’s family (arrow). B: GTG banded karyotype of the proband showing three derivative chromosomes. C: BAC-probes RP11-379C23 (green) (3q27. 2), RP11-190A24 (21q22.3) (orange) and RP11-89 N1 (red) (18q23) demonstrate a translocation among chromosomes 3, 21 and 18. D: BAC-probes TRP11-7H17 (18q23) (green), BAC-probe RP11-57 F7 (18q22.2) (red) and RP11-89H21(21q11.2) (orange) show the insertion of part of chromosome 18 in derivative chromosome 21.