Familial paracentric inversions inv(2)(q31q35) and inv(8)(q22.3q24.13) ascertained through reproductive abnormalities.

Two cases of familial paracentric inversion, one in the long arm of chromosome 2 and the other in the long arm of chromosome 8, are described. The first was ascertained in a woman who was studied because of recurrent abortions. The second was ascertained in the father of a girl with the trichorhinophalangeal syndrome and an interstitial deletion in 8q. The latter is the first case in which unequal crossing over in an inversion loop can be inferred in a male carrier of a paracentric inversion. The reasons for the relatively low frequency of paracentric inversions observed and factors which affect the pregnancy outcome are discussed.