Apparent monosomy of a G autosome in a Jamaican infant.

Monosomy of an autosome is widely thought to be lethal (Patau, I963). Deficiencies due to deletions of chromosomes I8 and 5 are well documented (de Grouchy, Lamy, Thieffry, Arthuis, and Salmon, I963; Lejeune, Lafourcade, Berger, Vialatte, Boeswillwald, Seringe, and Turpin, I963), and reciprocal translocations which can arise in a carrier person and result in unbalanced offspring with duplications/deficiencies are also described (Clarke, Stevenson, Davies, and Williams, I964; Uchida, Wang, Laxdal, Zaleski, and Duncan, I964; Cowie, Kahn, and O'Reilly, I965). Lejeune, Berger, Rethore, Archambault, Jerome, Thieffry, Aicardi, Broyer, Lafourcade, Cruveiller, and Turpin (I964) have also described a case in which they postulate mosaicism involving monosomy ofchromosome 21 with a partial monosomy of 2I.