INV(10)(P11.2Q21.2), A VARIANT CHROMOSOME

We present 33 families in which a pericentric inversion of chromosome 10 is segregating. In addition, we summarise the data on 32 families i n which an apparently identical inv(10) has been reported in the liter ature. Ascertainment was through prenatal diagnosis or with a normal p henotype in 21/33 families. In the other 12 families, probands were as certained through a wide variety of referral reasons but in all but on e case (a stillbirth), studies of the family showed that the reason fo r referral was unrelated to the chromosome abnormality. There has been , to our knowledge, no recorded instance of a recombinant chromosome 1 0 arising from this inversion and no excess of infertility or spontane ous abortion among carriers of either sex. We propose that inv(10)(p11 .2q21.2) can be regarded as a variant analogous to the pericentric inv ersion of chromosome 2(p11q13). We conclude that prenatal chromosome a nalysis is not justified for inv(10) carriers. In addition, family inv estigation of carrier status is not warranted in view of the unnecessa ry concern this may cause parents and other family members.