Apparent transmission distortion of a pericentric chromosome one inversion in a large multi-generation pedigree.

Pericentric chromosome inversions are often associated with infertility, recurrent pregnancy loss, and an increased risk for offspring with congenital anomalies. We report on a chromosome 1 inversion between 1p36.21 and 1q42.13, one of the largest described familial pericentric inversions of chromosome 1. The inversion was ascertained following the birth of a female with multiple congenital anomalies due to a recombinant chromosome 1. The inversion was subsequently detected or inferred in 16 healthy individuals over five generations. Interestingly, with a ratio of 16 carriers to 6 noncarriers, there appears to be transmission distortion of the inverted chromosome 1 within the family. Although there is no reported difficulty conceiving in the family, the risk of miscarriage is higher than predicted at 34% (13/38). The recurrence risk of a recombinant chromosome also appears to be lower than expected based on the mode of ascertainment. This case contributes to the spectrum of clinical features of chromosome 1 recombinants and raises the question of whether or not there is a selective advantage of the inverted chromosome at meiosis, conception, or post-zygotically that has contributed to transmission distortion of the inverted chromosome.