The human body is made up of trillions of cells. Within each cells nucleus there are 23 pairs of chromosomes. Each pair has one chromosome from your mother and one from your father. Each pair of chromosomes have hundreds of thousands of pairs of genes. Again, one of the pair of genes comes from your father and the other comes from your mother. The chromosome acts as a container for the genes. And the genes contain the instructions for the physical and biologicals traits of our body.
What is a gene mutation?
RP is a genetic disease. It is caused by a mutation in a gene that controls how the retina functions. The mutation is a mistake in the operation of the gene. Gene mutations are very rare with most people having or developing on average 60 mutations. Some mutations are inherited while others are caused by environmental factors. There are more than 50 different gene mutations that can cause RP. Scientists are continuing to find more through research.
Dominant, Recessive and X-Linked
There are 3 different variants of RP which are based on how the mutated gene is inherited. Autosomal dominant, Autosomal Recessive and X-Linked. Autosomal dominant is when the gene is inherited with only one copy of the mutated gene. This means that only one parent needs to pass on the mutated gene. This effectively makes the odds of inheriting the mutated gene, 50/50. Autosomal recessive means that the mutated gene requires 2 copies, not just one like with dominant, to inherit the disease. Both parents must have the same mutated gene, a gene that does not affect them adversely. Having only one copy, has no affect. Both variants are referred to as Autosomal. This means the gene is not located on the sex chromosome. As mentioned before there are 23 pairs of chromosomes. One of them determines the sex of the person. Women have 2 X chromosomes, men have 1 X chromosome and 1 y chromosome. The X-Linked variant has the mutated gene on the X chromosome. As a result, women are less likely to be affected by the mutated gene but are more likely to pass on the trait. Men are less likely to pass on the trait but are ore likely to be affected by the trait. The trait in this case is RP.
Genetic Testing
It is recommended that anyone with RP should look into genetic testing. The Foundation Fighting Blindness (www.fightingblindness.org) has a program where genetic testing can be done for free. It should be noted that the free test attempts to find which of 100 or so options your mutation may be. If that test doesn't identify the gene, there is a more extensive test that there is a charge. Further the FFB (Foundation Fighting Blindness) has a website called My Retina Tracker which allows patients to make their results available to researchers. The test and data only pertains to the genetic mutation that causes RP, no other genetic information is indentified or shared. You should ask your retina specialist about this testing.