A large deletion of the long arm of chromosome No. 4 in a child with limb abnormalities.

Abstract

No case of complete monosomy for a human autosome has as yet been reported. Examples of the trisomic condition which is produced by the same mechanism of non-disjunction are, however, relatively frequent. It must be assumed, therefore, that the monosomic state is less viable than the trisomic. Partial monosomic conditions have been described, some of which are related to a definite syndrome spectrum, but even these are rare in the population. The most authenticated case of partial monosomy was that first described by Lejeune, Lafourcade, Berger, Vialatte, Boeswillwald, Seringe, and Turpin (1963) and termed 'cri-du-chat' because of the peculiar cat-like cry associated with the condition: 61 cases have now been observed (Lejeune, Lafourcade, Berger, and Rethore, 1966b). The chromosome constitution is characterized by a partial deletion of the short arm of one of the No. 5 pair, later confirmed by German, Lejeune, Macintyre, and de Grouchy (1964) using 3H- thymidine autoradiography. Abnormalities associ- ated with deletions of the short arm of chromosome No. 4 have also been reported by Hirschhorn, Cooper, and Firschein (1965), Wolf, Porsch, Baitsch, and Reinwein (1965a), Wolf, Reinwein, Porsch, Schroter, and Baitsch (1965b), and Leao, Neu, and Gardner (1966); none, however, show a common clinical syndrome (Table ).