What SCID is in laymans terms

["Stephanie Wind" <wind@uswest.net>]

To have any immunity against disease, the body must have "antibodies". These
are molecules that bind to the antigen (disease causing agent). There is a
process by which the body changes the binding site of the antibodies so that
the antibodies can bind to different disease. In short, SCID makes this
process not work. The body cannot change the binding site and so the
antibodies don't recognize ANY diseases. The foal eventually dies from one
of the diseases that he has contracted. This process is controlled by a PAIR
of genes. A SCID carrier has ONE of the PAIR of genes that does not work.
The carrier will pass this bad gene on to half it's young. If a foal has TWO
copies of the SCID gene, then it will die of a disease sometime after it's
immunity gained from it's mother's collostrum has worn off.

Steph McCray