Precise reticulocyte counts are difficult to obtain by the manual method when their percentage in the blood is low or normal. In these instances, rapid reticulocyte counting by flow cytometry appears to offer more accuracy and precision. The purpose of this study was to establish reticulocyte counts in heterozygous beta-thalassemia for reference purposes and to evaluate the performance of the recently introduced apparatus R-1000 (Sysmex) in the very heterogeneous thalassemic and sickle-cell syndromes. We studied a total of 364 samples; 102 heterozygous beta-thalassemia carriers, 180 normal matched controls, 36 patients with thalassemia major or intermedia, and 46 patients with various sickle-cell syndromes. Reticulocyte counts (both as percentage and as total number) were higher in heterozygous beta-thalassemia than in normal controls (p less than 0.001) and showed an inverse correlation with the respective hemoglobin values (p less than 0.001). These results confirm the proposed slightly increased erythropoietic activity in heterozygous beta-thalassemia carriers. A drawback of the technique is that the reticulocyte-platelet discrimination error is signaled frequently in all conditions displaying a marked red cell heterogeneity, especially when these are associated with high reticulocyte numbers. This calls probably for readjustment of the corresponding algorithm. In addition, all these conditions show a significantly increased auramine-O mature red-cell nonspecific fluorescence.
Hemoglobin (Hb) disorders are common, potentially lethal monogenic diseases, posing a global health challenge. With worldwide migration and intermixing of carriers, demanding flexible health planning and patient care, hemoglobinopathies may serve as a paradigm for the use of electronic infrastructure tools in the collection of data, the dissemination of knowledge, the harmonization of treatment, and the coordination of research and preventive programs. ITHANET, a network covering thalassemias and other hemoglobinopathies, comprises 26 organizations from 16 countries, including non-European countries of origin for these diseases (Egypt, Israel, Lebanon, Tunisia and Turkey). Using electronic infrastructure tools, ITHANET aims to strengthen cross-border communication and data transfer, cooperative research and treatment of thalassemia, and to improve support and information of those affected by hemoglobinopathies. Moreover, the consortium has established the ITHANET Portal, a novel web-based instrument for the dissemination of information on hemoglobinopathies to researchers, clinicians and patients. The ITHANET Portal is a growing public resource, providing forums for discussion and research coordination, and giving access to courses and databases organized by ITHANET partners. Already a popular repository for diagnostic protocols and news related to hemoglobinopathies, the ITHANET Portal also provides a searchable, extendable database of thalassemia mutations and associated background information. The experience of ITHANET is exemplary for a consortium bringing together disparate organizations from heterogeneous partner countries to face a common health challenge. The ITHANET Portal as a web-based tool born out of this experience amends some of the problems encountered and facilitates education and international exchange of data and expertise for hemoglobinopathies.
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.
Large scale prevention programs for Thalassemia major or Sickle cell disease have already been set up in several places with high frequency of the deleterious genes. The Greek health authorities realized the magnitude of the problem and allowed the creation of a National Thalassemia Center in 1972. The incidence of thalassemia in Greece varies from 1-2 per cent up to 15%, the mean being around 8 per cent. With an annual number of births around 100,000, if no prevention measures are taken, the expected yearly number of newborns with thalassemia major in Greece should be of the order of 100-120. To these one should add a few decades of sickle cell patients, homozygotes or compound HbS/β-thalassemia heterozygotes. The total number of patients with thalassemia major now surviving is estimated at 4,000 plus another 600-800 patients with sickle cell disease. The National Thalassemia Center Center defined a network of peripheral Thalassemia Units in the major regional hospitals of the country, let them provide free carrier identification to couples requesting the test. When both partners were identified as carriers, they were given preliminary information locally and were referred to the Central Laboratory in Athens for further genetic counselling and, if so decided, prenatal diagnosis. Prenatal diagnosis was provided initially by fetoscopy and fetal blood biosynthesis; this approach was soon replaced by chorionic villi sampling and molecular techniques. The number of prenatal diagnoses carried out yearly over the last decade appears to cover the needs; the number of positive diagnoses is very close to the expected 25%, which also excludes overdiagnosis. The overall evaluation of the the program is reflected in the number of infants who were admitted to the pediatric clinics of the country in need of transfusion over the years the program was functioning. In fact, over the past years this number has steadily decreased to approximately 10 missed diagnoses annually, but has not reached zero as expected, after all this effort. The function of a comprehensive program for the prevention of thalassemia and HbS disease in Greece over the last 25 years has helped enormously in (a) avoiding birth of several hundreds of children with thalassemia major, thus (b) securing the use of the available resources for the optimal care of the patients who are living to-day, and (c) allowing thousands of couples at risk to give birth to healthy children.
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