Non-invasive prenatal testing (NIPT) is based on the detection and characterization of circulating cell-free fetal DNA (ccffDNA) in maternal plasma and aims to identify genetic abnormalities. At present, commercial NIPT kits can detect only aneuploidies, small deletions and insertions and some paternally inherited single-gene point mutations causing genetic diseases, but not maternally inherited ones. In this work, we have developed two NIPT assays, based on the innovative and sensitive droplet digital PCR (ddPCR) technology, to identify the two most common β thalassemia mutations in the Mediterranean area (β⁺IVSI-110 and β⁰39), maternally and/or paternally inherited, by fetal genotyping. The assays were optimized in terms of amplification efficiency and hybridization specificity, using mixtures of two genomic DNAs with different genotypes and percentages to simulate fetal and maternal circulating cell-free DNA (ccfDNA) at various gestational weeks. The two ddPCR assays were then applied to determine the fetal genotype from 52 maternal plasma samples at different gestational ages. The diagnostic outcomes were confirmed for all the samples by DNA sequencing. In the case of mutations inherited from the mother or from both parents, a precise dosage of normal and mutated alleles was required to determine the fetal genotype. In particular, we identified two diagnostic ranges for allelic ratio values statistically distinct and not overlapping, allowing correct fetal genotype determinations for almost all the analyzed samples. In conclusion, we have developed a simple and sensitive diagnostic tool, based on ddPCR, for the NIPT of β⁺IVSI-110 and β⁰39 mutations paternally and, for the first time, maternally inherited, a tool, which may be applied to other single point mutations causing monogenic diseases.

Hemoglobinopathies constitute the most frequent monogenic disorders worldwide and in Greece. In Greece, carrier frequency is estimated at about 8.0%, resulting in a heavy disease burden in the past. Therefore, the implementation of a national prevention program of the disease was an urgent necessity. Moreover, due to migration flow from different geographic areas in the last two decades, the observed spectrum of underlying mutations was expanded, leading to the adaptation of diagnostic approaches. We report the results of the National Thalassaemia Prevention Programme in Northern Greece, over a 15-year period (2001-2015). In total 33,837 healthy at-risk individuals (individuals or couples, 91.0% Greeks) were screened. We have screened 1598 pregnancies in 371 (23.0%) (10.0% non Greeks), of whom both parents carried gene defects and were offered genetic counseling. Seventy-six fetuses (23.0%) were predicted to be affected by severe forms of the disease. Following informed parental choices, 73 of the above pregnancies were terminated. Meanwhile, within the study period, 58 new thalassemic babies (five non Greeks) were referred to the Thalassaemia and Sickle Cell Disease Care Unit of Northern Greece, reflecting mostly parental unawareness, choice or the program failure. Based on the region’s population, the birth rate and the prevalence of the disease, the anticipated number of new cases is about 45 annually. According to our data, four thalassemic newborns were registered annually at a stable rate in the last 15 years, reaching a reduction of 90.0% of new affected births. Overall, the National Thalassaemia Prevention Programme effectively decreased the incidence of affected newborns in our region.

The BM88 antigen is a neuron-specific molecule widely distributed in the mammalian nervous system. It is a 22-kDa, apparently not glycosylated, integral membrane protein, which appears early during brain development and remains at high levels in the mature animal. Here, we describe the cDNA cloning of the porcine BM88 antigen and present evidence that this protein is involved in neuroblastoma cell differentiation. The deduced protein is a novel molecule consisting of 140 amino acids and bears a putative transmembrane domain at the COOH-terminal region. The mRNA of this protein is expressed only in neural tissues, where it is restricted to neurons. Stably transfected Neuro-2a cells overexpressing the BM88 antigen exhibited a significant change in morphology, reflected by enhanced process outgrowth, and a slower rate of division. Moreover, in the presence of differentiation agents, such as sucrose and retinoic acid, an accelerated differentiation of the transfected Neuro-2a cells was observed. Especially in the presence of sucrose, the consequent overexpression of the BM88 antigen in the transfected cells resulted in their enhanced morphological differentiation accompanied by the induction of neurofilament protein expression. Our results suggest that the BM88 antigen plays a role in the differentiation of neuroblastoma cells.