RT Journal Article SR Electronic T1 Segregation of a t(3;20) translocation through three generations resulting in unbalanced karyotypes in six persons. JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 446 OP 451 DO 10.1136/jmg.23.5.446 VO 23 IS 5 A1 Nielsen, K B A1 Tommerup, N A1 Jespersen, B A1 Nygaard, P A1 Kleif, L YR 1986 UL http://jmg.bmj.com/content/23/5/446.abstract AB With the aid of high resolution chromosome banding, a t(3;20) translocation was discovered in a large family with six retarded members. The translocation involved very small terminal segments. The unbalanced products resulting in partial trisomy 20q and monosomy 3p were observed in the retarded subjects. Gene localisation studies of the ADA gene, with a presumed locus on the long arm of chromosome 20, were also carried out and seem to exclude this gene from the distal part of 20q (20q13.1----qter).