Multiple cases of trisomy 9p/distal monosomy 18p in a family due to inherited translocation t (9:18).

A case of trisomy 9p/monosomy 18p in four members of a family is described. The mechanism of meiotic segregation is discussed in the sibs' mothers who are carriers of a balanced translocation t(9:18) (p 11.2; p 11.