An analysis of the break points of structural rearrangements in man.

The distribution of the points of breakage and reunion of a series of 58 Robertsonian translocations, 53 reciprocal translocations, and 10 inversions is described. An excess of 13/14 and 14/21 rearrangements was found among the Robertsonian translocations, this excess being independent of the method of ascertainment of the proband. The distribution of break points between chromosome arms in the reciprocal translocations, with the possible exception ofthe long arms of chromosome 11, was no different from that expected on the basis of their relative lengths. However, within arms there appeared to be an excess of breaks in the terminal regions, an excess of terminal/centromeric translocations where ascertain-