KNOXVILLE -- Scientists at the University of Tennessee, Knoxville, and Lawrence Berkeley National Laboratory (LBNL) have published new findings about a cause of a condition at the root of genetic disorders such as Down Syndrome, pregnancy loss and infertility.
Called aneuploidy, the condition is an abnormal number of chromosomes, and the research team found that if a mother's egg cell has a mutation in just one copy of a gene, called Bub1, then she is less likely to have offspring that survive to birth.
The findings appear in the online early edition of the Proceedings of the National Academy of Sciences for the week of July 13.
Sundar Venkatachalam, an assistant professor of biochemistry and cellular and molecular biology at UT Knoxville, originally was studying the gene for a possible connection to colon cancer, when he found his lab mice showed strange fertility characteristics.
"Where you would normally expect a female to have eight to 10 pups, there were only one or two pups that survived to term in the litters of females that had one copy of Bub1," said Venkatachalam. "So this was unusual when we were looking for cancer effects, especially in this group of females."
Ordinarily, both copies of a gene in a chromosome must carry the same mutation in order for an organism to be adversely effected, but the drastic effects of a single mutation were unexpected.
Venkatachalam, working with pathologist Robert Donnell at the UT College of Veterinary Medicine and LBNL researcher Francesco Marchetti, also found that the harmful effects of this mutation increased with a mother's age. As the female mice got older, there was eventually a complete loss of their ability to support a full-term pregnancy that lined up with an increase in aneuploidy. The same is true in humans: the chance of having an aneuploid pregnancy increases with the age of the mother.
For the past several years, scientists have used
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University of Tennessee at Knoxville