Autosomal Recessive Disease at a Glance

Monday, June 8, 2009
Welcome to the first issue of our Summer Knowledge Project! Since I will be covering, for the most part, the Autosomal Recessive Diseases this summer, I thought I would start with an overview. Next week we'll start the actual disease series with Tay-Sachs.

Recessive, in the case of genetic disorders, means that if a good gene exists, the good gene wins and the person does not have the disease. I know how this works firsthand because I am a carrier of the cystic fibrosis mutation Delta f508. Because I don't have two of these defective genes, or rather because one of the genes from my parents was a good gene, I don't have cystic fibrosis. The same holds true for any of these diseases. Because our daughter got a recessive gene from both my wife and myself (in her case she got Delta f508 from both of us), she has no good gene to be dominant. She has cystic fibrosis.

Because I have no known examples in my family of cystic fibrosis, and because Alicia's experiences in her family are fairly removed from her, it was a complete surprise to find out that our daughter had this disease. This is often the case. Since it only takes one good gene for a person to “be ok”, suddenly having a disease show up is a shock. This is how there are only roughly 30,000 cases of CF in America and yet there is an estimated 10 million carriers. In fact, it is a general rule that Autosomal Recessive Diseases are rare.

One of the easiest ways to understand Autosomal Recessive diseases is to view Gregor Mendel's drawings on how genetic codes are passed from parents to offspring. The Wikipedia entry shows the red/white combination wherein Red is a dominant color, and White is the recessive color. In the case of Autosomal Recessive diseases, white represents the defective gene. As you can see by the chart, each couple, when they both have the recessive gene present, have a 25% chance of passing the trait on to their offspring.

Parents of children with an Autosomal Recessive Disease are both automatically at level 2 in the chart. This is evidenced by the fact that they must have had a defective gene in order to produce a child with the disease, yet each also have one good gene, which keeps them from being anything more than carriers. I don't mean to get too technical here. It's important for the discussions that will follow, however, to have this background. The bottom line is that someone dealing with a Autosomal Recessive Disease is someone who needs your care, concern, and prayers.

My goal is not to drag us down in the knowledge of all things that can kill us and our children. Yet it is a simple fact that knowledge is the first weapon in knowing how to handle a disease. So if you know someone with the following diseases, take a few moments to learn as much as you can about your loved-one's condition and please, help whenever you can.

Here are the 10 diseases we'll cover over the next several weeks:
Alpers Syndrome
Autosomal Recessive Polycystic Kidney Disease
Cystic Fibrosis
Sickle Cell Anemia
Spinal Muscular Atrophy type I
Spinal Muscular Atrophy type II
Spinal Muscular Atrophy type III
Tay Sachs
Usher Syndrome