Partial karyotypes from patients 1-5 demonstrate the origin of CN aberrations of regions juxtaposed to 1q12. Successive hybridizations of chromosome pairs with different probe sets for 1p and 1q illustrate the CN changes or translocations in the respective chromosome arms. (A) Left bracket shows a normal pattern of probes on 1q (left) and 1p (right) on the normal chromosome 1 (patient 1). Right bracket demonstrates chromosome 1p triradial on the inv(1) showing branching of 1q12 (red) and 1 copy of 1q21 (green) to the left, whereas the same triradial chromosome on the right shows 2 copies of probes for 1p12 (green) and 1p13 (red). Triradials for 1p demonstrate the origin of a CN of 3 for 1p13. (B) Partial karyotype of patient 2 showing the same probe pattern as patient 1, with a normal pattern shown in the left bracket and gains of 1p in the right bracket. (C) Partial karyotype of patient 2 showing a novel whole-arm translocation of 1p to RC16q11 (aqua) with a CN gain of 1p. The left bracket shows a pattern of probes on inv(1), whereas the right bracket shows 1p translocation to RC16q11(aqua). Normal chromosome 1 is not shown. (D) Partial karyotype of patient 3 demonstrating the origin of CN gains of 2p and MYCN. The left bracket shows successive hybridization of a triradial of 2p. The triradial of 2p (left) originates on the der(1) showing the branching 1q12 probe (red). Rehybridization of same triradial (right) with a probe for MYCN (red) demonstrates an extra copy of MYCN and 1 copy of 1p12 (green) for the short arm. The right bracket shows normal 2 with probe for MYCN (red). Normal 1 and der(2) not shown. (E) Cell demonstrating triradial of 2p with FISH for MYCN and subsequently rehybridized with SKY (left bracket). The right bracket shows normal 2 by FISH and SKY. (F) FISH probes for 1q and 16q show whole-arm translocation of 1q12 to RC16(q11) (aqua). (G) Partial karyotype from patient 4 demonstrating CN gains of 1q21 originating on nonhomologous chromosome. A normal FISH pattern on chromosome 1 in left bracket. In the right bracket, a triradial of 1q12 (red) and 2 signals for 1q21 (green) on the der(2) demonstrate the origin of the 1q21 CN gain is the der(2). (H) Patient 5 demonstrates triradial of 1q21 on the normal 1 (left bracket) and a triradial of 1q12 on the der(9)(q11) (aqua) (right bracket), resulting in a CN of 4 for 1q21. (I) Patient 5 showing 1q12 decondensation in both the normal 1 (left bracket), and der(9) (middle bracket). The right bracket shows acentric (ace) copy of JT1q12 which will subsequently result in the formation of a micronucleus. FISH hybridizations to metaphase chromosomes are shown in inverse 4,6 diamidino-2-phenylindole to delineate G-banding patterns.