I am quite busy, so I will be brief, but we can discuss it more later.

basically, there are many variabilities in the genome, which are called polymorphisms. some are of no clinical significance, others become important only in our response to certain medications, and other can cause diseases, or be a risk factor for diseases.

it was once thought that only those parts of the DNA that code proteins are important and all the rest is "junk". we now know that this is not true. in fact the non-coding regions have other roles (some of which I am sure we are yet to find) among which are regulation of other genes, by silencing them.

the way to discover new genetic abnormalities is by familial studies, and genetic physicians just love those cultures were there is a lot of in-breeding and cousins getting married to each other, because then they can get a lot of data from relatively few people.

the fact that so many people in your family are affected in various ways, strongly suggests that there is some mutation (possibly not yet discovered).
and if all those that are affected have this mutation, and all those that are not, don't have it, then most likely it is the cause of your illness.

alice