Synthesis a Publication of UC Davis Cancer Center

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Her specialties are two rare forms of mental retardation, Prader-Willi syndrome and Angelman's syndrome, which are thought to be caused by deletions on chromosome 15. If the missing gene occurs on the mother's chromosome, Angelman's syndrome is the result. If it occurs on the father's chromosome, Prader-Willi syndrome is the consequence. This phenomenon in which defects occur depending on whether the mutation takes place on the either the mother's or father's chromosome is called parental imprinting.

A similar mechanism affects some cancer cells, LaSalle explains, except that the mutations that cause genetic defects in babies are inherited or occur in the egg or sperm. Mutations that cause tumors to grow in adults, however, occur in individual cells.

"Since genes within imprinted chromosomal regions are only expressed on one chromosome, a deletion on the other chromosome in a single cell would result in the total absence of expression of that gene," LaSalle explains. "Many imprinted genes are involved in basic mechanisms of cell growth, so the loss of such genes in cells could cause cancer."

Photo right: Postgraduate researcher Carlo Lagdamen at the laser-scanning cytometer.