Asynchronous replication of alleles in genomes carrying a microdeletion

While most allelic pairs of DNA replicate synchronously during the S phase of the cell cycle, some genes normally replicate asynchronously, i.e., genes on the X chromosome and imprinted genes. The replication control mechanism is unknown but was shown to be impaired in malignancies and chromosomal trisomies where replication pattern becomes asynchronous.

To determine the level of asynchronization in replication timing of cells from patients with microdeleted genomes.

We applied monocolor fluorescent in situ hybridization with different probes on leukocytes from microdeleted genomes.

All samples derived from the microdeleted genomes showed significantly higher levels of an asynchronized pattern compared to normal individuals.

Even a "small" genetic imbalance (microdeletion) can interfere with gene replication and cell cycle progression, as previously shown in full trisomies.