Screening for fetal chromosomal anomalies like Trisomy 21 (Down syndrome) during pregnancy has been a routine part of prenatal care for decades. Identifying pregnancies at risk for single gene autosomal recessive disorders is also possible prenatally but not until recently has it been possible to identify couples at risk for having a baby with these Mendelian disorders though universal carrier screening. These tests use either blood or saliva samples collected from individuals so that the DNA can be isolated and processed using micro-array technology to screen for 100-plus disease causing mutations that would manifest as a lethal disease in subsequent offspring of carrier parents. Preconception carrier screening allows couples to consider all of their reproductive options before conception since carrier parents would have a one-in-four chance of having an affected child. These choices can include early prenatal diagnostic testing with or without pregnancy termination, use of donor gametes or voluntary sterility or the best choice, preimplantation genetic diagnosis (PGD).
As many as one in four individuals who are screened using Universal Genetic Testing panels will be identified as a carrier of at least one autosomal recessive disease. However, when both partners are screened, relatively few couples (less than 1%) are found to be at risk of having an affected child. Across all ethnic groups the most common carrier frequencies for clinical significant disorders are cystic fibrosis (CF), DFNB1 nonsyndromic hearing loss and deafness, spinal muscular atrophy (SMA), familial Mediterranean fever, Smith-Lemli-Opitz syndrome, sickle cell disease/beta-Thalessemia, and Gaucher disease. Universal Genetic Testing will identify patient’s risks for passing on genetic disorders so that interventions such as PGD can be done. This will minimize the risk of having a child with a serious birth defect.