Genetics Question

Thomas Weber tomweber at
Thu Dec 28 09:03:41 EST 1995

Hi there,
In principal there are two types of genetic diseases, so called 
dominantly inhereted diseases and so called recessively inhereted 
diseases. All eucaryotes, including man, have two copys of their genome, 
with one exception which I will adress later.In dominantly inhereted 
diseases it is sufficient that one copy of the respective gene is defect 
to cause the disease. In these cases there is no such thing as a 
carrier, if you have the gene you have the illness; It is, however, 
possible that your children do not have the disease as you can inherit 
the healthy copy of your gene (every individual has one copy of the 
genome of the father and one of the mother).An example of such a disease 
is Chorea Huntington.
In the more common case of recessive diseases both copys of the 
respective gene have to be defect to get the disease, an example is 
Cystic Fibrosis. The disease you have is obviously one of the latter 
case. You say that your father is a carrier, this means that he has one 
healthy and one defect copy of the respective gene. Dependending on the 
disease he has no symptons at all or mild ones, because he has still one 
healthy copy of the gene. The fact that your father is carrier and you 
and your sister have the disease further suggests that the disease is 
not linked to one of the sex chromosomes X and Y (men are XY and women 
XX, this is the exception I mentioned above).

I hope this short information helps you


Thomas Weber

P.S.: I would suggest that you discuss this issue with your doctor, or 
if he can't give you the right answer with a geneticist, it is much 
easier this way than online. 

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