1. Ronan was born with Tay-Sachs, a rare genetic disorder.

2. Tay-Sachs is most common among Askenazi Jews and French Canadian populations, while cystic fibrosis is mostly seen in people of Northern European descent.

3. Unfortunately, there is no treatment for Tay-Sachs disease, so it is very important for carriers or possible carriers to have genetic counselling.

4. So-called recessively inherited disorders, such as Tay-Sachs disease[ ], cystic fibrosis and red blood cell disorders known as thalessemias are rare.

5. These enlarged, pale neurons are in a baby with Tay-Sachs disease, which is seen mostly in persons of European Jewish heritage.

6. For those thinking of starting a family, it could alert them to their risk of having a baby with cystic fibrosis, Tay-Sachs and other genetic disorders.

7. PGD is good for screening for specific genetic disorders such as cystic fibrosis and Tay-Sachs disease, and also can be used to select gender.

8. But increased intelligence may have come at a cost, with genetic disease such as Tay-Sachs being side effects of genes that facilitate intelligence.

9. But Cassandra said she likes that I have different genes, arguing that when, for instance, Jews procreate with other Jews, they increase their kids' risk for breast cancer and Tay-Sachs.

10. Prospective parents who discover they're silent carriers of the gene for a disease like Tay-Sachs.