Gene silencer may be a smart bomb!
In a recent conversation with Dr. Herwig Lange of the George Huntington Institute in Munster, Germany, I was casually asked what my thoughts were regarding an article published in 2015 by The Economist, entitled A Faustian Bargain concerning the evolution of the human brain which asked the question of whether the key to that process could be found in Huntington's Disease.
It was an interesting read; however, one particular paragraph grabbed my attention due to the fact that I could relate to it on a personal level in regards to my wife who is now in late-stage Huntington's Disease.
I'm sure that many in the HD community can remember speaking of a loved one who became stricken with HD in a way that was complimentary of their intelligence or agility and mourned the loss of a beautiful mind to the disease. I have often done this while reminiscing about family members that have fallen ill or have passed from this dreaded disease; cousins, aunts, uncles, etc., marveling at bits of wisdom they imparted or by their ability to be so able to figure things out or by being great in sports. Most of my recollections, of course, involved my wife Sheila whom I have repeatedly touted as one of the most intelligent persons I have ever met or knew well. There are many examples of this, but the most telling was the fact that she did not graduate from high school due to being raised poor and having parents that were abusive and did not place a high value on education. However, she did gain acceptance to one of the best universities in the country solely based on her IQ later in life.
The segment of the article that struck me was of a study by Dr. Peg Nopoulos of the University of Iowa entitled: D17 Effects of the huntingtin gene (HTT) on brain development. In the study, Dr. Nopoulos and her team have tested 80 children (so far) between the ages of 6 and 18. The team tested the children's cognitive and motor skills and compared these volunteers’ test performances and brain scans with their CAG counts. According to the Economist, the study "found a strong correlation between the number of repeats and a child’s test performances. More repeats are associated with both higher intelligence and better physical coordination (the former effect seems more pronounced in girls and the latter in boys)." They also found a correlation between repeat numbers and the volume of the basal ganglia as well as the volume of the cerebral cortex which is another area of the brain affected by HD.
In the next part of the study, they enrolled kids between the ages of 8 to 18 and completed a total of 394 evaluations. They found "greater repeats lengths were associated with larger ICV and higher IQ until a peak at roughly 41 repeats. Above the peak, increasing repeat lengths were associated with lower ICV and lower IQ. Other brain measures showed sex-specific findings with repeat lengths affecting the striatum and cerebellum in males, and the cortex and thalamus in females."
What this shows is that HTT plays a major role in brain development. Higher CAG repeats result in higher IQs up to a certain point where they result in disease. What some fear is that new gene silencing drugs, such as one developed by IONIS, which reduces the HTT protein, may actually restrict brain development in the long term. For those of us in the HD community, it raises important questions.
A two-part question would be: Can any impairment of brain development be measured in a few short years, and with the absence of children in the study would it even be a factor at all?