Well before companies ever invited consumers to send saliva by mail in exchange for their genome sequence, would-be parents used genetic tests to determine whether heritable conditions might affect their offspring.
The differences between the two types of testing are small but significant, notes Cheri Schoonveld, MS, CGC, a certified genetic counselor at the University of Minnesota in Minneapolis. While genome sequencing seeks to identify an individual’s risk of developing a condition, like Alzheimer’s disease, family-planning tests focus on a different kind of risk.
“Individuals who are carriers are not at risk to develop the condition themselves; however, they are at increased risk to have a child with the condition.”
Because certain gene mutations are more common to particular ethnicities, the American College of Obstetricians and Gynecologists recommends that couples be offered carrier screening for heritable conditions associated with their ethnicity. Examples include cystic fibrosis for Europeans, Tay-Sachs disease for Ashkenazi Jewish families, and sickle-cell disease for families with African heritage.
Still, like all genetic tests, these predict only potential outcomes. “Most genetic conditions that are screened for require that both parents be carriers of the condition to have an affected child, and even if both parents are carriers, it does not mean that every child will have the condition,” Schoonveld explains. For autosomal recessive conditions like these, the risk that a child would be affected is one in four.
Schoonveld recommends couples consider carrier testing before pregnancy, so they can review the information without the “pressure and emotional charge” that a pregnancy involves. They can then decide to move forward, more prepared for possible outcomes, or to pursue other options, such as in vitro fertilization with genetic testing of embryos, or adoption.
This originally appeared as part of “Is Genetic Testing Right for You?” in the December 2016 issue of Experience Life.
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