gettingolderbytheday

To correct some mistaken assumptions that have been posted: Someone could have Late Onset Tay Sachs who is now in Shiduchim and his parents were tested by DY, since when the parents married as much as 35 – 40 years ago, they did not really know about LOTS, and they used a serum test, not DNA, to test for Tay Sachs when they first started DY. As long as there was more than 50% Hex A in the blood stream, they were presumed not to be carriers. Now, since they use DNA, they will flag a potential couple with LOTS mutations as well.
Also, only one parent has to have the LOTS mutation while the other can have the regular TS mutation and the child will have a 25% of getting LOTS. If both parents have the LOTS mutation (a statistically miniscule possibility, but it happens) the child has a 25% chance of having a very mild form of the condition.
It is also really important to point out that there are many variants of LOTS, even with the same mutation, and even in the same family. Some people with the condition are wheelchair bound by their 30’s or earlier, but others can be in their 50s before they are impacted in any significant way. It depends on the amount of Hex A in the system, and how efficiently the body uses it.