Friday, December 23, 2005

New twist to stuttering genes

I have decided to spend a bit more time to read up on genetics during the Xmas and New Year period, and write a popular-scientific article about the genetics of stuttering. I have been encouraged in my endeavors by the Pennsylvania court decision that it is still OK to talk about and teach evolution without reference to intelligent design. :-)

Most research on genetics and stuttering has revolved around twin studies or looking for genes or combinations in samples like families where most members stutter: see a previous post. This new article on stuttering and genetics puts a new spin on the issue and in the right direction. A gene alone is not enough, it seems. You need the right combination of genes, or the right conditions for the gene to have important effects: read about the Epistasis effect. The researchers suggest that maternal age at birth might be such a epistatic factor.

Maternal age at the birth of the first child as an epistatic factor in polygenic disorders.

The identification of the genes for complex, polygenic disorders has proven difficult. This is due to the small effect size of each gene and genetic heterogeneity. An additional important factor could be the presence of unidentified epistatic factors. In the broad definition of epistasis, the effect of one unit is not predictable unless the value of another unit is known and one of the units may not be a gene. We have previously identified maternal age as an epistatic factor for the effect of the LEP gene on the age of onset of menarche. We report here the effect of maternal age and the age of the mother at the birth of her first child (maternal age 1st) as epistatic factors for the interaction of the dopamine D1 gene (DRD1) with obsessive-compulsive behaviors and with stuttering. The epistatic effects of maternal age 1st were stronger than maternal age. This type of epistatic factor may be generalizable to many other gene-trait interactions.

The science journal Science has named new research on genetics of other brain disorders like dyslexia and Tourette syndrom as a 2005 Breakthrough topic. I will talk about this in my next post, and be desperately trying to make a connection PDS.


Anonymous said...


Remember to apply your criteria of
Thursday, November 24, 2005 to the research.


Tom Weidig said...

I will try my best! :-)

But as I am not very familiar with the details of genetics, I will probably have a closer look at a few textbooks, before launching myself in writing...