Mentor: Dr. Beth Sullivan
The centromere of a chromosome is critically important for genomic stability and cell division. However, breaks in the chromosome can lead to dicentric chromosomes, which have two centromeres instead of one. One in 1000 people have a dicentric X chromosome, making them the most common dicentric. Every centromere in human chromosomes has CENP-A, a centromere specific protein that protects the centromere and aids in cell division. When dicentric X chromosomes are first formed, each centromere has a normal amount of CENP-A. With 100% protein at each centromere, the chromosome will be torn as the two centromeres are pulled in different directions during division. Therefore, the dicentric X chromosome reduces the amount of CENP-A at each centromere to ensure the chromosome is viable. In monocentric chromosomes, a decrease in CENP-A leads to increased sister chromatid exchange, which is a marker for instability. To determine if this finding is true for dicentric X chromosomes, chromosome oriented in situ hybridization (COFISH) was used on patient cells as well as engineered dicentric X chromosomes to test the stability of centromeres. (insert results here)
