Monday, April 13, 2009

More genetics

Along with the information given to us by the doctors, I have been doing most of the research myself. Reading published medical journals/reports, etc. I try to stay away from getting my info from personal websites, as we all know those can sometimes be snow jobs, laced with persuasive information and biased opinions.

I found some interesting information in a published report "Genotyping Microarray (Disease Chip) for Leber Congenital Amaurosis: Detection of Modifier Alleles" by the The Association for Research in Vision and Ophthalmology, Inc.

I will stay away from posting all the very scientific medical jargon that will just leave you more confused. I love science and medicine, and it's taking me a while to digest all the compound, enzyme, protein names affected by the 6 identifying chromosomes on the DNA causing LCA. For now I will just post some number facts that I found interesting.

The odds of detecting a third allele (not heterozygous or homozygous) means it would be a new mutation of the disease in our family. Since Gavin is the first, it's possible. Different forms of one type of gene are called different alleles of that gene. Mutations are random events that change the sequence of a gene and therefore create a new allele. It's all possible Gavin carries the new mutation.

The incidence of LCA is estimated to be between 1 in 50,000 and 1 in 100,000 persons (i.e., approximately 1/75,000). Assuming that six LCA genes account for approximately 50% of the cases, we could expect a total of 12 LCA genes, resulting in 1 in 900,000 individuals harboring a specific genetic form of LCA. This means that 1 in 225,000 marriages is at risk, and that 1 in 474 individuals carry a specific LCA-associated genetic defect. Therefore, it is expected that 12 of 474, or 1 in 40, individuals are carriers of a disease-causing LCA mutation by chance.

When it all gets narrowed down, 1 in 40, is rare, but not that rare. Of course, that is just individuals who are carriers of the disease (Troy and/or myself). That means the mutation can happen with just one parent carrying the genetic defect, if it shows both me and Troy are not recessive carriers for vision loss.

Very interesting!

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