Risk determination in cases with an extra minute chromosome: prenatal diagnosis

The interpretation of an extra minute chromosome (EMC) detected in utero presents both diagnostic and prognostic problems. Two EMC cases are presented and a flow-chart guideline is proposed for the determination of developmental risk. A prenatally detected EMC was familially inherited through a normal phenotype father. The pregnancy was continued and a normal baby boy was delivered. At one year his development was within normal ranges. The second EMC case was a mentally retarded girl examined at 4 years and 7 months of age. The EMC was identified with a combination of various staining techniques to be an inversion duplication (15). The importance of differential diagnosis of EMCs by DA/DAPI staining is emphasized.