High‐level induction of fetal haemoglobin by pomalidomide in β‐thalassaemia/HbE erythroid progenitor cells

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155942/1/bjh16670.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155942/2/bjh16670_am.pd

Reactivation of a developmentally silenced embryonic globin gene

The α- and β-globin loci harbor developmentally expressed genes, which are silenced throughout post-natal life. Reactivation of these genes may offer therapeutic approaches for the hemoglobinopathies, the most common single gene disorders. Here, we address mechanisms regulating the embryonically expressed α-like globin, termed ζ-globin. We show that in embryonic erythroid cells, the ζ-gene lies within a ~65 kb sub-TAD (topologically associating domain) of open, acetylated chromatin and interacts with the α-globin super-enhancer. By contrast, in adult erythroid cells, the ζ-gene is packaged within a small (~10 kb) sub-domain of hypoacetylated, facultative heterochromatin within the acetylated sub-TAD and that it no longer interacts with its enhancers. The ζ-gene can be partially re-activated by acetylation and inhibition of histone de-acetylases. In addition to suggesting therapies for severe α-thalassemia, these findings illustrate the general principles by which reactivation of developmental genes may rescue abnormalities arising from mutations in their adult paralogues

An international registry of survivors with Hb Bart's Hydrops Fetalis Syndrome

Hb Bart's Hydrops Fetalis Syndrome (BHFS) resulting from α0-thalassemia is considered a universally fatal disorder. However, over the last three decades improvements in intrauterine interventions and perinatal intensive care have resulted in increasing numbers of BHFS survivors. We have initiated an international registry containing information on 69 patients, of which 31 are previously unpublished. In this perspective we analyze the available clinical information to document the natural history of BHFS. In future, once we have accrued sufficient cases, we aim to build on this study and provide information to allow counseling of at-risk couples. To date 39 patients have survived beyond the age of 5 years, 18 of whom are now older than 10 years. Based on the available cases we find evidence to suggest that intrauterine therapy provides benefits during the perinatal and neonatal period, however, it may not provide additional benefits to long-term growth and neurodevelopmental outcomes. Growth retardation is a major adverse long-term outcome among BHFS patients with ~40% being severely affected in terms of weight and ~50% in terms of height. There is also an increased risk of neurodevelopmental delay as we find 20% (11/55) of BHFS survivors suffer from a serious delay of ≥6 months. Most patients in the registry require lifelong transfusion and often have associated congenital abnormalities and co-morbidities. This perspective is a first step in gathering information to allow provision of informed counseling on the predicted outcomes of affected babies

An international registry of survivors with Hb Bart's Hydrops Fetalis Syndrome

Hb Bart's Hydrops Fetalis Syndrome (BHFS) resulting from α0-thalassemia is considered a universally fatal disorder. However, over the last three decades improvements in intrauterine interventions and perinatal intensive care have resulted in increasing numbers of BHFS survivors. We have initiated an international registry containing information on 69 patients, of which 31 are previously unpublished. In this perspective we analyze the available clinical information to document the natural history of BHFS. In future, once we have accrued sufficient cases, we aim to build on this study and provide information to allow counseling of at-risk couples. To date 39 patients have survived beyond the age of 5 years, 18 of whom are now older than 10 years. Based on the available cases we find evidence to suggest that intrauterine therapy provides benefits during the perinatal and neonatal period, however, it may not provide additional benefits to long-term growth and neurodevelopmental outcomes. Growth retardation is a major adverse long-term outcome among BHFS patients with ~40% being severely affected in terms of weight and ~50% in terms of height. There is also an increased risk of neurodevelopmental delay as we find 20% (11/55) of BHFS survivors suffer from a serious delay of ≥6 months. Most patients in the registry require lifelong transfusion and often have associated congenital abnormalities and co-morbidities. This perspective is a first step in gathering information to allow provision of informed counseling on the predicted outcomes of affected babies

The integrity and stability of specimens under different storage conditions for glucose-6-phosphate dehydrogenase deficiency screening using WST-8

Accurate measurement of glucose-6-phosphate dehydrogenase (G6PD) activity is critical for malaria treatment as misclassification of G6PD deficiency could cause serious harm to patients. G6PD activity should be assessed in blood samples on the day of collection. Otherwise, specimens should be stored under suitable conditions to prevent loss of G6PD activity. Here, we assessed stability and integrity of G6PD testing in samples from normal controls, heterozygous females, and G6PD deficient individuals using water-soluble tetrazolium salts (WST-8) assay. Specimens were stored as ethylenediaminetetraacetic acid (EDTA) whole blood and dried blood spots (DBS) at various temperatures (37 °C, room temperature, 4 °C and -20 °C) and under different humidity conditions (with and without desiccant). G6PD normal samples were stable for up to 1 year when stored at -20 °C under controlled conditions, with 85% and 91% G6PD activity in EDTA whole blood and DBS in the presence of desiccant, respectively. Specimens from heterozygous females showed greater G6PD activity when stored as DBS, with 85% enzyme activity after 1 year of storage at -20 °C under controlled conditions in the presence of desiccant. G6PD deficient samples rapidly lost enzyme activity in all storage conditions tested. However, the reduction in G6PD enzyme activity in G6PD deficient samples did not interfere with G6PD classification. Samples stored under suitable conditions for G6PD testing will allow accurate measurement of enzyme activity, prevent misclassification of G6PD deficiency and enable safe and effective use of antimalarial drugs such as primaquine and tafenoquine

Mutations in Kruppel-like factor 1 cause transfusion-dependent hemolytic anemia and persistence of embryonic globin gene expression.

In this study, we report on 8 compound heterozygotes for mutations in the key erythroid transcription factor Krüppel-like factor 1 in patients who presented with severe, transfusion-dependent hemolytic anemia. In most cases, the red cells were hypochromic and microcytic, consistent with abnormalities in hemoglobin synthesis. In addition, in many cases, the red cells resembled those seen in patients with membrane defects or enzymopathies, known as chronic nonspherocytic hemolytic anemia (CNSHA). Analysis of RNA and protein in primary erythroid cells from these individuals provided evidence of abnormal globin synthesis, with persistent expression of fetal hemoglobin and, most remarkably, expression of large quantities of embryonic globins in postnatal life. The red cell membranes were abnormal, most notably expressing reduced amounts of CD44 and, consequently, manifesting the rare In(Lu) blood group. Finally, all tested patients showed abnormally low levels of the red cell enzyme pyruvate kinase, a known cause of CNSHA. These patients define a new type of severe, transfusion-dependent CNSHA caused by mutations in a trans-acting factor (Krüppel-like factor 1) and reveal an important pathway regulating embryonic globin gene expression in adult humans