I enjoyed reading your web pages re Retinoblastoma.

My son had unilateral RB and his eye was removed over 17 years ago. He had to have regular EUA's to check on his other eye until he was old enough to be examined without "A".

We went to a meeting last Saturday of the RB Society here in England where my attention was drawn to your pages. We had a talk about the genetics of RB The RB society seeks to make people (especially GP's) aware of RB and of the treatment options available. It also seeks to provide support for parents of newly diagnosed children and to raise funds for research into RB. The society has an Annual meeting in London. There are also some regional groups who meet more often.

Last Saturday was the AGM. One of the attendees told how he had surfed the internet looking for Retinoblastoma and had found one site. He had his PC there so that anyone interested could look. This announcement was made at the end of the meeting and my wife was anxious to get home. So I repeated the search yesterday and found your page. The society is looking to having a home page - but has not yet done so. I will let you know when it happens.

We had two geneticists at the meeting. One is Genetic Counselor, the other doing research. From memory .....

You have two sets of chromosomes so you inherit from both parents. What you pass on is just one set of genes - so there is a 50% chance that you will pass on the defective gene if you have one.

If in any cell, one of the RB genes is working correctly, then no tumor. It takes both copies to be defective to get a tumor. If one gene is damaged you only have to have the other one fail to get a tumor - but of course there is a chance that you will come through "unscathed" - so the chance that a "RB carrier" gets RB is "<"100%, perhaps 80-90% (I don't remember the figure quoted but it was something like that). So the chance of the child of an RB carrier getting RB is 90% of 50% = 45%.

After the age of about 5, all(?) growth in the eye is suppressed and therefore the risk of RB developing after that time diminishes.

The RB gene is quite long and all of it is important for the suppression of tumors. To examine the chromosome looking for defects in the RB gene is a long process. Therefore, it is difficult to look at a person's genetic material to determine if they have inherited a defective RB gene. However, what is relatively easy is, having found out the nature of the defect in one family member, to check on other members to see if the same defect is present. If you're looking for a needle in a haystack, it helps to know what the needle looks like and in which bit of the haystack it is to be found. Ideally, they like to have some tumor material because that helps narrow down the search.

The RB society publishes a quarterly magazine and this can be e-mailed. When I remember, I will make a note of the address of the editor and pass it on to you so that you can request a copy. I think that the next edition will have a report of the meeting with much more detail than I have remembered.

Looking back on Paul's problem it seems that we got of "very lightly". By the time he had been diagnosed I understand that the tumor was quite large. Pressure was building up in his eye because the retina had become detached and was blocking the "drain" through which excess liquid is released. The eye was removed and we have a catalog of stories about his "glass eye". It wasn't until several years later that we saw how some children have bilateral tumors and the various therapies to save as much sight as possible.

Sends Ian some Email. at Ian.Davidson@UnitedKingdom.NCR.COM