The simplest answer to this question is that there is no magic number.

We used to offer limited testing for specific diseases based on a person’s ethnicity. However, we have learned that this can be problematic—many people do not know their precise ethnic origins, and many diseases can be found in multiple ethnicities. Given this, we might miss carriers if the testing performed is too specific.

Advances in research and technology now allow testing to be done using expanded pan-ethnic sequencing panels. In simpler English, these are panels that cover hundreds of diseases that might affect many ethnicities. See JScreen’s testing panel here

Genetic counselors or clinical geneticists help to explain the testing process and details, including categories of conditions on these panels and the chances of being a carrier.

Finally, it is important to recognize that the best time to pursue this type of testing is before contemplating a pregnancy, and that there may be updates to consider before subsequent pregnancies.