High measured cobalamin (vitamin B12) concentration attributable to an analytical problem in testing serum from a patient with pernicious anemia.

tocol (costs of $39 and $4, respectively). An advantage of using AF supernatant is its availability without interfering with current standards of care or compromising fetal health. Another is the ability to freeze the supernatant sample at 80 °C without risking significant degradation of DNA over time (7 ). For research applications, the development of an optimized protocol could allow further investigation of the origin and kinetics of cffDNA. Finally, placental abnormalities and pregnancyassociated disorders may affect cffDNA concentrations in maternal serum (8, 9), whereas fetal disorders and contact between fetal organs (such as lungs, kidneys, and the gastrointestinal system) and AF may affect cffDNA concentrations in AF.