Abstract
Five members of a family with a balanced insertion (1;5)(q32;q11q22) are presented. The daughter of one of them shows multiple malformations and a partial trisomy for the long arms of chromosome No. 5 (5q11 to 5q22 segment) resulting from a 'aneusomie de recombinaison' in her mother. The propositus' karyotype is 46,XX,rec(1;5)ins (1;5)(q32;q11q22). This case is the first reported example of an insertion between two chromosomes followed by 'aneusomie de recombinaison'. It also is the first reported case of trisomy invovling the long arms of chromosome No. 5.