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.
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.
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
Thalassemia
Usher Syndrome
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