This Week in Sickle Cell News October 7th to the 14th

By Sean Marshall

Not much in news updates this week however there was one interesting article that surfaced this week that needs to be seen.  

An article on science20.com has surfaced shedding some light on cell conversion and how DNA bias may keep some diseases in circulation. It was explained by a new study out of the University of Pennsylvania that investigated the process in the context of evolution of human population and the genetic traits that follow said populations. The study was conducted by researchers Joseph Lachance and Sarah A. Tishkoff and ultimately the study found that “certain types of DNA sequences were found in gene conversion.” This according to the article may be an important factor in why certain hereditary disease persist more heavily in some population around the world then others.   

The study outlined some reasons for why certain populations have genetic disorders one such example was the Amish. There research concluded that “have a higher risk of several genetic diseases due in part to a phenomenon called founder effects, whereby certain genes rise to prevalence in populations that originated with a relatively small number of individuals.”  

When it came to sickle cell anemia the team had some interesting comments about sickle cell traits, “the classic example is sickle-cell anemia. It's an evolutionary trade-off because people with one copy of a sickle-cell mutation are highly protected from malaria.” If this is true it has some severe implications on how future generation of people with sickle cell can and will be treated.  

The article also went on to say one of the reasons why the sickle cell gene is passed from person to person “Previously, researchers have found that during gene conversion DNA is more likely to be retained and copied if the allele that differs contains either a guanine (G) or a cytosine (C) nucleotide. Conversely, the DNA is more likely to be converted, or replaced, if the allele contains an adenine (A) or thymine (T). “

This means if there is a strong gene that is different and can provide some sort of genetic edge it would be copied. So we go back and find out the same gene that causes sickle cell also protect against malaria and is a strong genetic strain. However it was explained that even though the bias is small other factors come into play. “This bias is very small," Lachance said. "It's like a very slightly weighted coin. But over generations and across huge amounts of the genome, flipping the coin over and over again, we thought we would start to see an effect at the population level.

This article is so very important to go over because it is essential outlining why sickle cell exists and why scientists are having such a difficult time in destroying it. I would recommend reading the article in full detail. I've gone over the key points but there is still much more to go over.  

The link to the article is here: http://www.science20.com/news_articles/cell_conversion_and_how_dna_bias_may_keep_some_diseases_in_circulation-146184




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