Both Sarah Palin and Rick Santorum have as their youngest child an infant affected by chromosomal abnormalities. Sarah's child has Trisomy 21, Down Syndrome, and Rick's youngest child has Trisomy 18. I had never heard of Trisomy 18 before but this is a very, very sad condition to have, with limited life expectancy, severe disabilities, etc.  To get a clearer idea of what Trisomy 18 is, go to read…