A chromosome rearrangement in orangutan studied with Q-, C-, and G-banding techniques.

A constitutional chromosome rearrangement is a phenotypically normal male organutan is described. The rearrangement resulted from three breakages in chromosome 9 and involved a pericentric inversion and additional reciprocal transpositions of the terminal segments of both arms. Q-, G-, and C-banding studies were carried out, and it was shown that the chromosomes affected was a member of the only pair in the complement that lacked a centromeric C-band and that its G-banding pattern closely resembled that of chromosome 12 in man. The origin of the rearrangement and the role of such rearrangement in producing chromosome polymorphisms are discussed, particularly in relation to evolution and speciation. An additional pair of heteromorphic chromosomes (No.23) is also described. The short arm satellited region of one member of the pair was found to be variable and strongly C-banded.