Of 27 translocations, we found 26 to be of paternal origin and only one of maternal origin.

: J Med Genet. 2009 Jul 27. [Epub ahead of print]
De novo apparently balanced translocations in man are predominantly paternal in origin and associated with a significant increase in paternal age.Thomas NS, Morris JK, Baptista J, Ng BL, Crolla JA, Jacobs PA.
Salisbury District Hospital, United Kingdom.

BACKGROUND: Congenital chromosome abnormalities are relatively common in our species and among structural abnormalities the most common class is balanced reciprocal translocations. Determining the parental origin of de novo balanced translocations may provide insights into how and when they arise. While there is a general paternal bias in the origin of non-recurrent unbalanced rearrangements, there are few data on parental origin of non-recurrent balanced rearrangements. METHODS: The parental origin of a series of de novo balanced reciprocal translocations was determined using DNA from flow sorted derivative chromosomes and linkage analysis. RESULTS: Of 27 translocations, we found 26 to be of paternal origin and only one of maternal origin. We also found the paternally derived translocations to be associated with a significantly increased paternal age (p<0.008). CONCLUSION: Our results suggest there is a very marked paternal bias in the origin of all non-recurrent reciprocal translocations and that they may arise during one of the numerous mitotic divisions that occur in the spermatogonial germ cells prior to meiosis.