Not all chromosome imbalance resulting from the 11q;22q translocation is due to 3:1 segregation in first meiosis

Abstract
The constitutional translocation between chromosomes 11 and 22 [t(11;22)(q23.3;q11.22)] is one of the best known rearrangements in the human genome. Hitherto only one type of unbalanced karyotype, namely 47,XX or XY,+der(22) t(11;22)(q23.3;q11.2) was found among offspring of the translocation carriers. This result is the product of a 3:1 segregation at meiosis. We report an alternative unbalanced karyotype. The proband's karyotype is 47,XY,t(11;22)(123.3;q11.2), +der(22)t(11;22)(q23.3;q11.2)pat. This finding cannot be due to nondisjunction in first meiosis of the translocation carrier.