Replication and inactivation of an isodicentric X: presence of an inactive centromere influences the replication patterns.

An isodicentric X-chromosome (idic(X)(pter leads to q23::q23 leads to pter)) was found in a phenotypically normal 30-year-old female with symptoms of premature menopause. A study of DNA replication revealed that in a proportion of cells there was an asymmetric pattern of replication. The region with the inactive centromere had a tendency to replicate later than the portion with the functioning centromere.