PRENATAL DETECTION OF AN INVERTED X-CHROMOSOME IN A MALE

An unusual case of an X chromosome with a pericentric inversion (p11.3 q21.3) was detected prenatally in a male fetus. This inversion has not been previously characterized. Although the inverted chromosome was t ransmitted through the mother, no living males on the maternal side we re detected with the aberrant chromosome. Replication studies were per formed on cultures of maternal peripheral blood lymphocytes, and it wa s determined that the inverted X chromosome was early replicating in a pproximately half of the cells. Following genetic counseling, the preg nancy was continued and a healthy male infant was delivered at term. C ytogenetic analysis of peripheral blood performed in the newborn perio d confirmed the prenatal findings. The child is developing normally at 3 years of age.