The association of acrocentric chromosomes in 1000 normal human male metaphase cells

Associations among the acrocentric chromosomes of man were first described by FergusonSmith & Handmaker (1961) and Harnden (1961). Various investigators have suggested that such associations, in conjunction with other prominent heteropycnotic secondary constrictions, play a role in the organization of nucleoli (Schultz & St Lawrence, 1949; Ohno et al. 1961; Hungerford, 1964 ; Ferguson-Smith, 1964). Participation of the acrocentric chromosomes in such associations has been postulated to increase the risk of non-disjunction with subsequent trisomic conditions of groups D and G (Harnden, 1961; Ferguson-Smith & Handmaker, 1961). In fact, several families possessing chromosomally abnormal individuals have been purported to exhibit possible ‘increased satellite association’ (Tips et al. 1964; Kiossoglou et al. 1964; Lyons, Thompson & Bigley, 1966; Zellweger, Abbo & Cuany, 1966; Abbo, Zellweger & Cuany, 1966). However, studies of this type have not been too well defined and in some cases both cytogenetically normal and abnormal individuals have been compared directly (Van Brink, Los & Nienhaus 1962; Froland & Mikkelsen, 1964; Bishun, 1966; Zellweger et al. 1966; Abbo et al. 1966). Such comparisons pose difficulties since the number of acrocentric chromosomes may not be the same in each case, e.g. trisomic and normal individuals. In addition, population data from a large series of normals on the frequency and distribution of satellite associations are meagre. In this paper, we present data on various aspects of satellite associations, in the hope that such results might form a basis for comparison between normal individuals and persons with abnormal cytogenetic constitutions.