Implementation of third-generation digital PCR for non-invasive prenatal diagnosis of sickle cell disease and early detection

Sickle Cell Disease (SCD) is one of the most prevalent autosomal recessive disease, affecting over 600,000 newborns globally each year. In Spain, the Spanish Registry of Hemoglobinopathies (REHem) has registered 1142 cases. Despite improvements in treatments, prophylaxis, and vaccines, it remains a chronic condition requiring lifelong care. Allogeneic transplantation is the only cure, contingent upon the availability of an HLA-compatible donor. SCD is considered a rare disease in some population, resulting from a mutation of a single nucleotide in codon 6 GAG>GTG (HBB: c.20A>T) of the β-globin gene, producing hemoglobin S (HbS), altering the shape of red blood cells and obstructing circulation, leading to severe complications in multiple organs. Heterozygous individuals (βS/βA) have the ‘sickle cell trait,’ typically asymptomatic. Homozygotes experience symptomatic disease, with chronic and acute infarctions in organs and tissues, episodes of intense pain, cerebral infarctions, splenomegaly, massive hemolytic episodes, and acute chest syndrome, causing a risk of premature death increasing the threat of premature mortality. Prenatal diagnosis provides expecting couples with information about the fetus’s genetic health, enabling informed decision-making. Although conventional techniques are invasive and carry risks, Non-Invasive Prenatal Diagnosis (NIPD) has been developed using cell free fetal DNA (cffDNA) in maternal blood to determine the fetus’s genotype. However, the co-presence of maternal DNA and cffDNA, along with the low concentration of the latter, has been a challenge in non-invasive studies. We present the results of a pilot study where the use of digital PCR (dPCR) has been established for NIPD of SCD, a highly sensitive technique allowing the detection of mutations in low-frequency samples, presenting itself as a safe alternative for SCD diagnosis.