Abstract
Prenatal diagnosis of hemoglobinopathies involves the study of fetal material from blood, amniocytes, trophoblast coelomatic cells and fetal DNA in maternal circulation. Its first application dates back to the 70s and it involves globin chain synthesis analysis on fetal blood. In the 1980s molecular analysis was introduced as well as amniocentesis and chorionic villi sampling under high-resolution ultrasound imaging. The application of direct sequencing and polymerase chain reactionbased methodologies improved the DNA analysis procedures and reduced the sampling age for invasive prenatal diagnosis from 18 to 16–11 weeks allowing fetal genotyping within the first trimester of pregnancy. In the last years, fetal material obtained at 7–8 weeks of gestation by coelocentesis and isolation of fetal cells has provided new platforms on which to develop diagnostic capabilities while non-invasive technologies using fetal DNA in maternal circulation are starting to develop.
Highlights
Contributions: MV, AG study concept and design, writing the manuscript and critical manuscript revision; MC, FC data acquisition and writing the manuscript; FL, CP data analysis and interpretation and critical manuscript revision; GD, CJ, FP, GS, VC, DR final approval of the version to be pub
The traditional basic hematological tests for thalassemia are the measurement of the mean corpuscular volume (MCV), the mean corpuscular hemoglobin value and the quantity of HbA2, HbF and the eventual homozygotes for b-thahemoglobins (Hb) variants
Primers used as probes are designed to anneal immediately adjacent to the mutated site and their lengths differ from at least five bases by addition to the 5’ end of a polyT tail to distinguish them by capillary electrophoresis
Summary
At 16-23 weeks of gestation, the synthesis of b-chains in the second trimester, to suppress maternal reticulocyte globin gene synthesis of b-chains respect to g-chains was i.e. in normal human fetus it is less than 10%24,25 synthesis;[35] ii) fetal red cell concentration with calculated between 5-15% in normal fetuses, and further reduction of b-chain synthesis in differential agglutination using anti-i serum;[36] between 3.5-6% in carriers of b-thalassemia, both b-trait and affected fetus Many of these iii) fetal red cell enrichment with antibodies and below 3% in case of affected fetuses.[41] problems were successively solved but the last against blood group antigens (ABO, MNs, Rh each center determined their own and not least, which is the emotional burden of systems);[37] iv) differential lysis of maternal synthetic ratios depending from the heterointerrupting an advanced pregnancy. RFLPs were no frequently used for prenatal diagnosis except in a few cases in which individual
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