De novo appearance of a translocation t(5p; 2Iq), and its transmission in both balanced and unbalanced forms to the next generation.

A family is described in which a reciprocal translocation involving 5p and 21q appeared de novo in the chromosome complement of a woman who then transmitted it in both balanced and unbalanced form to her progeny. The proposita, a child with the cri du chat syndrome, had a deficiency for most of 5p, all of 21p, 21 centromere, and a small proximal segment of 21q. The reported cases of the cri du chat syndrome associated with translocations are reviewed and discussed in relation to this family.