Mendilian Genetics; or, Why Can't I Curl my Tongue?

For the past few days I have been investigating genetic traits. These traits are determined by alleles. You receive one allele from each of your parents. These alleles can carry the genetic code for a dominant or recessive gene. If you receive two dominant alleles or one dominant and one recessive allele, you will express the dominant trait. If you receive two recessive alleles you will express the recessive trait. I tested myself and a variety of my family members for four different traits. These traits were: attached ear lobes, widow's peak, hitchhiker's (bent) thumb, and ability to curl your tongue. My findings are below.

From this chart I was able to create the following three pedigrees:

Pedigree for Attached Earlobes. 

Pedigree for Widow's Peak

Pedigree for Tongue rolling

I was quite surprised that only one member of my family had unattached earlobes, none of my family had widow's peaks, and that neither my cousin, my brother, nor myself was able to roll our tongues while our parents could. I found this odd because unattached earlobes are dominant, widows peaks are dominant, and tongue rollers are dominant. I was unable to create several pedigrees because my grandparents could have been AA and Aa or Aa and Aa. There were several such situations, in which it was impossible to find a result.

Gene Therapy

A diagram explaining Gene Therapy

Imagine the treatment of a cancer patient. It is typically a long string of doctors appointments, surgeries, and medications such as chemotherapy. But what if there was a way to treat cancer with a simple injection? It seems incredible, and yet this is the aim of a new type of medical treatment called gene therapy. Not only would gene therapy treat cancer, but it could also treat cystic fibrosis, familial hypercholesterolemia, HIV/AIDS, gaucher disease, hearing loss, and could allow patients with circulatory problems in the legs to avoid amputation.

So, how would this incredible process work? It would begin on a molecular level. All of the aforementioned diseases and complications are caused by imperfections and mutations of the DNA. These are obviously very hard to treat with medications, and are typically hereditary. They can affect almost any part of the DNA. It is clearly quite hard to change a gene that is written into each and every cell in the human body, and coming up for a cure for these diseases has always been quite daunting. This is where gene therapy comes in. Gene therapy is the use of genes as treatment or prevention for diseases.

Using genes as a treatment? As fantastical as it sounds, this is the reality of gene therapy.  A "normal" gene is put into the genome in place of an "abnormal" gene which causes a disease or disfunction. This is done with several different treatments which fall under two headings: Germ-line gene therapy and somatic gene therapy. Germ-line gene therapy is when genes are introduced into reproductive cells or into embryos, so that the child will not have genetic abnormalities. On the other hand, somatic gene therapy is when therapeutic genes are inserted into cells to replace the current DNA or to make a protein/substance that is not present or not working in the patient. Most current research is developing somatic gene therapy.

Somatic gene therapy usually works via a "vector". The vector delivers the new gene to the patients cells. These vectors are almost always a virus which has had the infectious DNA replaced with the proper gene. These are either a retrovirus (such as HIV, which works well in dividing cells), an Adenovirus (such as the common cold, which works well in non-dividing cells), an Adeno-associated virus (which inserts DNA at a specific singular site on chormosome 19) or Herpes simplex virus (typically causes cold sores). There are new ways of developing gene therapy, including introducing the DNA directly to the cells, creating an artificial lipid with a water-based core which can travel directly through a cell membrane to deliver the gene, chemically linking the DNA to a molecule that attaches to the cell receptors, or even adding a 47th chromosome, which would not affect the cell in any way other than changing the defective gene.

Like any advancement in science, there are some questions and possible complications that come up when discussing gene therapy. If we put aside the omnipresent issue of "playing god", there are still a few problems. The primary problem is the use of viruses. Many scientists and researchers fear that one of the viruses injected into the DNA will go awry. Instead of being completely removed, the original virus would still retain its own DNA and begin infecting people. Although this is a justified concern, I believe that the benefits far outweigh the risks. If the makers of the injections are thorough in their testing, the company can have a product that is both safe and infinitely helpful to the modern world.

Check out this game about gene therapy!

http://ghr.nlm.nih.gov/handbook/therapy/genetherapy

http://www.ornl.gov/sci/techresources/Human_Genome/medicine/genetherapy.shtml

http://www.encyclopedia.com/topic/gene_therapy.aspx

http://autocww.colorado.edu/~toldy2/E64ContentFiles/VirusesMoneransAndProtists/RetrovirusB1.html

A Gene that can Cure Cancer and Diabetes?

When you think of a cure for cancer and diabetes, what comes to mind? Probably scientists, hard at work in a lab. But surely not a group of Ecuadorians who are all under three and a half feet tall. According to this article, scientists have discovered a that these people are immune not only to cancer, but also to diabetes. This is because they have a disease known as Laron syndrome, and it may be the key to finding a cure for two very deadly diseases.


The cause of this syndrome is directly tied to the cell cycle. It turns out that Laron syndrome is caused by a specific mutation of a gene which is a receptor for Human Growth Hormone. This gene is known as IGF-1, and if a person has Laron syndrome they have very little IGF-1. Therefore, the Human Growth Hormone is not accepted by the cells, and the person does not grow. This ties into the ideas of proto-oncogenes and tumor suppressors. Certain parts of the cell, called proto-oncogenes, tell the cell when to go through the cell cycle and split apart. If there are no proto-oncogenes, as with Laron syndrome, the cell will not split.


This is a remarkable progression in the war against cancer and other deadly diseases. If scientists can find a way to change the ways our genes deal with the Human Growth Hormone to cure cancer without harming us in any other way, it would be truly remarkable. However, I highly doubt this could happen. It is always dangerous to mutate a person's genes, and without proper checks this could create even larger problems than cancer itself. Nevertheless, it seems that the secret to curing cancer could really have been hiding in a small village of Ecuador.




Sources:
http://www.nytimes.com/2011/02/17/science/17longevity.html?_r=1