just about everyone carries a gene for at least one genetic disorder — even if it’s never shown up in your family history. if you have a mutation in just one set of genes, you’re what’s known as a “carrier”: you’re carrying the genes for a genetic disorder but have no signs of the disease. most carrier screening is for recessive disorders. it takes two genes to pass on these mutations. our carrier blood test will determine what, if any mutations you and your partner may be carriers for. this will determine if it’s possible for you to pass on any of these diseases to your child. if both you and your partner are carriers, further testing and evaluation is necessary to ensure you don’t pass this disease to your future child.
rarely, a condition (like huntington’s disease) can be caused by a mutation in just one set of dna. but in most cases — including cystic fibrosis and sickle cell anemia — it takes a mutation in both sets of dna, one from the egg and one from the sperm, for a child to actually be affected by a genetic disease.
if both parents are carriers of a recessive gene for a disorder, there is a 25 percent (1-in-4) chance that their child will get the gene from each parent and will have the disorder. there is a 50 percent (1-in-2) chance that the child will be a carrier of the disorder—just like the carrier parents.
typically, we will test one partner first (usually the one with a uterus). if test results show that the first partner is not a carrier, then no additional testing is needed. if test results show that the first partner is a carrier, the other partner is tested.