Case Report: Identification of an HNF1B p.Arg527Gln mutation in a Maltese patient with atypical early onset diabetes and diabetic nephropathy.

BACKGROUND: The diagnosis of atypical non-autoimmune forms of diabetes mellitus, such as maturity onset diabetes of the young (MODY) presents several challenges, in view of the extensive clinical and genetic heterogeneity of the disease. In this report we describe a case of atypical non autoimmune diabetes associated with a damaging HNF1ß mutation. This is distinguished by a number of uncharacteristic clinical features, including early-onset obesity, the absence of renal cysts and diabetic nephropathy. HNF1ß-MODY (MODY5) is an uncommon form of monogenic diabetes that is often complicated by a wide array of congenital morphological anomalies of the urinary tract, including renal cysts. This report expands on the clinical phenotypes that have been described in the context of HNF1ß mutations, and is relevant as only isolated cases of diabetic nephropathy in the setting of MODY5 have been reported. CASE PRESENTATION: An obese Maltese female with non-autoimmune diabetes, microalbuminuria, glomerular hyperfiltration, fatty liver and no renal cysts was studied by whole exome sequencing to investigate potential genes responsible for the proband's phenotype. A rare missense mutation at a highly conserved site in exon 8 of HNF1ß was identified (c.1580G > A, NM_000458.3, p.Arg527Gln), with multiple in-silico predictions consistent with pathogenicity. This mutation has not been previously characterised. Additionally, several common susceptibility variants associated with early-onset obesity, polygenic type 2 diabetes and nephropathy were identified in the proband that could impose additional effects on the phenotype, its severity or its clinical course. CONCLUSION: This report highlights several atypical features in a proband with atypical diabetes associated with an HNF1ß missense mutation. It also reinforces the concept that monogenic causes of diabetes could be significant contributors to disease burden in obese individuals with atypical diabetes.

Genetic causes of Parkinson's disease in the Maltese: a study of selected mutations in LRRK2, MTHFR, QDPR and SPR.

BACKGROUND: Mutations in Leucine-rich repeat kinase 2 NM_198578 (LRRK2 c.6055G > A (p.G2019S), LRRK2 c.4321C > G (p.R1441G)) and alpha-synuclein NM_000345 (SNCA c.209G > A (p.A53T)) genes causing Parkinson's disease (PD) are common in Mediterranean populations. Variants in the Quinoid Dihydropteridine Reductase NM_000320 (QDPR c.68G > A (p.G23D)), Sepiapterin Reductase NM_003124 (SPR c.596-2A > G) and Methylenetetrahydrofolate Reductase NM_005957 (MTHFR c.677C > T and c.1298A > C) genes are frequent in Malta and potential candidates for PD. METHODS: 178 cases and 402 control samples from Malta collected as part of the Geoparkinson project were genotyped for MTHFR polymorphisms, QDPR and SPR mutations. Only PD and parkinsonism cases were tested for SNCA and LRRK2 mutations. RESULTS: LRRK2 c.4321C > G and SNCA c.209G > A were not detected. The LRRK2 c.6055G > A mutation was found in 3.1 % of Maltese PD cases. The QDPR mutation was found in both cases and controls and did not increase risk for PD. The SPR mutation was found in controls only. The odds ratios for MTHFR polymorphisms were not elevated. CONCLUSIONS: The LRRK2 c.6055G > A is a cause of PD in the Maltese, whilst QDPR c.68G > A, SPR c.596-2A > G and MTHFR c.677C > T and c.1298A > C are not important determinants of PD.

Spatiotemporal expression and control of haemoglobin in space.

It is now widely recognised that the environment in space activates a diverse set of genes involved in regulating fundamental cellular pathways. This includes the activation of genes associated with blood homoeostasis and erythropoiesis, with a particular emphasis on those involved in globin chain production. Haemoglobin biology provides an intriguing model for studying space omics, as it has been extensively explored at multiple -omic levels, spanning DNA, RNA, and protein analyses, in both experimental and clinical contexts. In this study, we examined the developmental expression of haemoglobin over time and space using a unique suite of multi-omic datasets available on NASA GeneLab, from the NASA Twins Study, the JAXA CFE study, and the Inspiration4 mission. Our findings reveal significant variations in globin gene expression corresponding to the distinct spatiotemporal characteristics of the collected samples. This study sheds light on the dynamic nature of globin gene regulation in response to the space environment and provides valuable insights into the broader implications of space omics research.

Sepiapterin reductase deficiency: a treatable mimic of cerebral palsy.

OBJECTIVE: Sepiapterin reductase deficiency (SRD) is an under-recognized levodopa-responsive disorder. We describe clinical, biochemical, and molecular findings in a cohort of patients with this treatable condition. We aim to improve awareness of the phenotype and available diagnostic and therapeutic strategies to reduce delayed diagnosis or misdiagnosis, optimize management, and improve understanding of pathophysiologic mechanisms. METHODS: Forty-three individuals with SRD were identified from 23 international medical centers. The phenotype and treatment response were assessed by chart review using a detailed standardized instrument and by literature review for cases for which records were unavailable. RESULTS: In most cases, motor and language delays, axial hypotonia, dystonia, weakness, oculogyric crises, and diurnal fluctuation of symptoms with sleep benefit become evident in infancy or childhood. Average age of onset is 7 months, with delay to diagnosis of 9.1 years. Misdiagnoses of cerebral palsy (CP) are common. Most patients benefit dramatically from levodopa/carbidopa, often with further improvement with the addition of 5-hydroxytryptophan. Cerebrospinal fluid findings are distinctive. Diagnosis is confirmed by mutation analysis and/or enzyme activity measurement in cultured fibroblasts. INTERPRETATION: Common, clinical findings of SRD, aside from oculogyric crises and diurnal fluctuation, are nonspecific and mimic CP with hypotonia or dystonia. Patients usually improve dramatically with treatment. Consequently, we recommend consideration of SRD not only in patients with levodopa-responsive motor disorders, but also in patients with developmental delays with axial hypotonia, and patients with unexplained or atypical presumed CP. Biochemical investigation of cerebrospinal fluid is the preferred method of initial investigation. Early diagnosis and treatment are recommended to prevent ongoing brain dysfunction.

Decentralized energy in flexible energy system: Life cycle environmental impacts in Belgium.

Decentralized energy systems enable a higher integration of electricity generation by renewable energy sources supported by electric storage and may significantly reduce greenhouse gas emissions for electricity generation. While the environmental impact of single technologies has received great attention in recent years, the environmental impacts of decentralized energy generation and storage technologies remain unaddressed. This study presents a cradle-to-grave life cycle assessment of those technologies in Belgium for 2030 and 2050. The system technologies comprise single-Si photovoltaic installations combined with lithium-ion and second-life batteries. To compile the life cycle inventory (LCI), energy balances are built based on a Belgian impact energy model. The flexibility of the energy system is introduced by different EV charging strategies and distinct modes of stationary battery storage with the Belgium electricity grid, represented by four different scenarios: i) low flexibility, ii) medium flexibility, iii) high flexibility, and iv) high flexibility with high prosumer potential (PPH). The midpoint impact categories climate change, land use, mineral resource scarcity and terrestrial ecotoxicity of ReCiPe life cycle impact assessment method are analyzed. The decentralized energy generation and storage technologies in Belgium in 2050 result in 64.51 gCO2eq/kWh of consumed electricity for the medium flexibility scenario, representing a 72 % decrease compared to 2014. However, these reductions are driven by changes in the national electricity mix. Land use impacts are also reduced, up to 72 % for the high flexibility PPH scenario. In contrast, mineral resource scarcity and terrestrial ecotoxicity rise over time in the high flexibility PPH scenario in 2050 to 46 % and 66 %, respectively. A perturbation analysis is conducted to assess the sensitivity of the results, showing solar irradiation as the most sensitive parameter. One way to further reduce the environmental impacts of decentralized energy systems could be to investigate new strategies for the end-of-life of photovoltaic installations and batteries.

A comparative profile of total protein and six angiogenically-active growth factors in three platelet products.

Objectives: Platelet-derived products have been shown as promising novel therapeutic agents for chronic wounds. However, their clinical use requires a greater degree of method standardisation, part of which involved more extensive cataloguing of their biochemical composition. This study aimed to quantify and compare total protein and 6 angiogenically-active growth factors in three distinct platelet products. Methods: Platelet Lysate (PL, n=5), Calcium-activated Platelet Rich Plasma (Ca-PRP, n=5) and Platelet-Rich Fibrin (PRF, n=5) were prepared from pooled platelet apheresis products (n=10). Ca-PRP and PRF were prepared from the same units (n=5) by activation with 20 mmolL-1 calcium chloride. PL was prepared from the remaining (n=5) units using an established lysate. Total protein was quantified with the Bradford Assay. Sandwich enzyme-linked immunosorbent assay was used to quantify six growth factors: epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), stromal cell derived growth factor-1α (SDF-1α), endostatin, and transforming growth factor-ß1 (TGF-ß1). Results: Protein retrieval differed significantly (p<0.05) between the three products: PL (11.35±0.80 mg/mL) < Ca-PRP (20.44±8.17 mg/mL) < PRF (40.67±3.13 mg/mL). Growth factor yield was considerable in all three products and differed significantly for: VEGF (PL

Epigenomic analysis of KLF1 haploinsufficiency in primary human erythroblasts.

Haploinsufficiency for the erythroid-specific transcription factor KLF1 is associated with hereditary persistence of fetal hemoglobin (HPFH). Increased HbF ameliorates the symptoms of ß-hemoglobinopathies and downregulation of KLF1 activity has been proposed as a potential therapeutic strategy. However, the feasibility of this approach has been challenged by the observation that KLF1 haploinsufficient individuals with the same KLF1 variant, within the same family, display a wide range of HbF levels. This phenotypic variability is not readily explained by co-inheritance of known HbF-modulating variants in the HBB, HBS1L-MYB and/or BCL11A loci. We studied cultured erythroid progenitors obtained from Maltese individuals in which KLF1 p.K288X carriers display HbF levels ranging between 1.3 and 12.3% of total Hb. Using a combination of gene expression analysis, chromatin accessibility assays and promoter activity tests we find that variation in expression of the wildtype KLF1 allele may explain a significant part of the variability in HbF levels observed in KLF1 haploinsufficiency. Our results have general bearing on the variable penetrance of haploinsufficiency phenotypes and on conflicting interpretations of pathogenicity of variants in other transcriptional regulators such as EP300, GATA2 and RUNX1.

Recommendations for genetic variation data capture in developing countries to ensure a comprehensive worldwide data collection.

Developing countries have significantly contributed to the elucidation of the genetic basis of both common and rare disorders, providing an invaluable resource of cases due to large family sizes, consanguinity, and potential founder effects. Moreover, the recognized depth of genomic variation in indigenous African populations, reflecting the ancient origins of humanity on the African continent, and the effect of selection pressures on the genome, will be valuable in understanding the range of both pathological and nonpathological variations. The involvement of these populations in accurately documenting the extant genetic heterogeneity is more than essential. Developing nations are regarded as key contributors to the Human Variome Project (HVP; http://www.humanvariomeproject.org), a major effort to systematically collect mutations that contribute to or cause human disease and create a cyber infrastructure to tie databases together. However, biomedical research has not been the primary focus in these countries even though such activities are likely to produce economic and health benefits for all. Here, we propose several recommendations and guidelines to facilitate participation of developing countries in genetic variation data documentation, ensuring an accurate and comprehensive worldwide data collection. We also summarize a few well-coordinated genetic data collection initiatives that would serve as paradigms for similar projects.

Immunoglobulin G in Platelet-Derived Wound Healing Factors.

We intended to reformulate an existing platelet-derived wound healing formula to target each phase of the healing wound with the appropriate phase-specific molecules. A decreased perfusion of the skin, often associated with conditions such as thalassemia, sickle cell disease, diabetes mellitus, and chronic vascular disease, is the most common etiology of cutaneous ulcers and chronic wounds. We had previously shown that a PDWHF topically applied to a chronic nonhealing ulcer of a ß-thalassemia homozygote stimulated and accelerated closure of the wound. The PDWHF was prepared from a pooled platelet concentrate of a matching blood group, consisting of a combination of platelet α-granule-derived factors. Processing of the apheresis-pooled platelets yielded various amounts of proteins (3.36 g/mL ± 0.25 (SD) (N = 10)) by the better lysis buffer method. Immunoglobulin G was found to be the most abundant α-granule-secreted protein. Equally broad quantities of the IgG (10.76 ± 12.66% (SD) (N = 10)) and IgG/albumin ratios (0.6 ± 0.4 (SD) (N = 10)) were quantified. We have developed a method using a reformulated lysis buffer followed by size exclusion chromatography and affinity chromatography to extract, identify, quantify, and purify IgG from activated platelets. IgG purification was confirmed by Western blot and flow cytometry. It was thought unlikely that the platelet IgG could be accounted for by adsorption of plasma protein, though the variable quantities could account for diversity in wound healing rates. The IgG could protect the wound even from subclinical infections and functionally advance healing. It may be useful in the management of skin ulcers in the early phase of wound healing.

GYNOCARE Update: Modern Strategies to Improve Diagnosis and Treatment of Rare Gynecologic Tumors­Current Challenges and Future Directions

More than 50% of all gynecologic tumors can be classified as rare (defined as an incidence of ≤6 per 100,000 women) and usually have a poor prognosis owing to delayed diagnosis and treatment. In contrast to almost all other common solid tumors, the treatment of rare gynecologic tumors (RGT) is often based on expert opinion, retrospective studies, or extrapolation from other tumor sites with similar histology, leading to difficulty in developing guidelines for clinical practice. Currently, gynecologic cancer research, due to distinct scientific and technological challenges, is lagging behind. Moreover, the overall efforts for addressing these challenges are fragmented across different European countries and indeed, worldwide. The GYNOCARE, COST Action CA18117 (European Network for Gynecological Rare Cancer Research) programme aims to address these challenges through the creation of a unique network between key stakeholders covering distinct domains from concept to cure: basic research on RGT, biobanking, bridging with industry, and setting up the legal and regulatory requirements for international innovative clinical trials. On this basis, members of this COST Action, (Working Group 1, "Basic and Translational Research on Rare Gynecological Cancer") have decided to focus their future efforts on the development of new approaches to improve the diagnosis and treatment of RGT. Here, we provide a brief overview of the current state-of-the-art and describe the goals of this COST Action and its future challenges with the aim to stimulate discussion and promote synergy across scientists engaged in the fight against this rare cancer worldwide.

Hb Valletta [beta87(F3)Thr-->Pro] and Hb Marseille/Long Island [beta2(NA2)His-->Pro; (-1)Met-(+1)Val-(+2)Pro-Leu], in a unique compound heterozygote with a normal hemoglobin phenotype.

This study refers to the quantitative hemoglobin (Hb) phenotype of a 19-year-old female with Hb Valletta [beta87(F3)Thr-->Pro] in association with Hb Marseille/Long Island [beta2(NA2)His-->Pro; (-1)Met-(+1)Val-(+2)Pro-Leu] and a normal Hb electrophoretogram. The data serve to alert investigators to the possibility that relatives with apparently normal Hb phenotypes may be transmitting mutant alleles and suggest methods for identification.

An electronic infrastructure for research and treatment of the thalassemias and other hemoglobinopathies: the Euro-mediterranean ITHANET project.

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.

Identification of an HNF1A p.Gly292fs Frameshift Mutation Presenting as Diabetes During Pregnancy in a Maltese Family.

The diagnosis of maturity onset diabetes of the young (MODY) is a challenging process in view of the extensive clinical and genetic heterogeneity of the disease. Mutations in the gene encoding hepatocyte nuclear factor 1α (HNF1A) are responsible for most forms of monogenic diabetes in Northern European populations. Genetic analysis through a combination of whole exome sequencing and Sanger sequencing in three Maltese siblings and their father identified a rare duplication/frameshift mutation in exon 4 of HNF1A that lies within a known mutational hotspot in this gene. In this report, we provide the first description of an HNF1A-MODY3 phenotype in a Maltese family. The findings reported are relevant and new to a regional population, where the epidemiology of atypical diabetes has never been studied before. This report is of clinical interest as it highlights how monogenic diabetes can be misdiagnosed as either type 1, type 2, or gestational diabetes. It also reinforces the need for a better characterisation of monogenic diabetes in Mediterranean countries, particularly in island populations such as Malta with a high prevalence of diabetes.

The EuroBioBank Network: 10 years of hands-on experience of collaborative, transnational biobanking for rare diseases.

The EuroBioBank (EBB) network (www.eurobiobank.org) is the first operating network of biobanks in Europe to provide human DNA, cell and tissue samples as a service to the scientific community conducting research on rare diseases (RDs). The EBB was established in 2001 to facilitate access to RD biospecimens and associated data; it obtained funding from the European Commission in 2002 (5th framework programme) and started operation in 2003. The set-up phase, during the EC funding period 2003-2006, established the basis for running the network; the following consolidation phase has seen the growth of the network through the joining of new partners, better network cohesion, improved coordination of activities, and the development of a quality-control system. During this phase the network participated in the EC-funded TREAT-NMD programme and was involved in planning of the European Biobanking and Biomolecular Resources Research Infrastructure. Recently, EBB became a partner of RD-Connect, an FP7 EU programme aimed at linking RD biobanks, registries, and bioinformatics data. Within RD-Connect, EBB contributes expertise, promotes high professional standards, and best practices in RD biobanking, is implementing integration with RD patient registries and 'omics' data, thus challenging the fragmentation of international cooperation on the field.

Systematic documentation and analysis of human genetic variation in hemoglobinopathies using the microattribution approach.

We developed a series of interrelated locus-specific databases to store all published and unpublished genetic variation related to hemoglobinopathies and thalassemia and implemented microattribution to encourage submission of unpublished observations of genetic variation to these public repositories. A total of 1,941 unique genetic variants in 37 genes, encoding globins and other erythroid proteins, are currently documented in these databases, with reciprocal attribution of microcitations to data contributors. Our project provides the first example of implementing microattribution to incentivise submission of all known genetic variation in a defined system. It has demonstrably increased the reporting of human variants, leading to a comprehensive online resource for systematically describing human genetic variation in the globin genes and other genes contributing to hemoglobinopathies and thalassemias. The principles established here will serve as a model for other systems and for the analysis of other common and/or complex human genetic diseases.

Haploinsufficiency for the erythroid transcription factor KLF1 causes hereditary persistence of fetal hemoglobin.

Hereditary persistence of fetal hemoglobin (HPFH) is characterized by persistent high levels of fetal hemoglobin (HbF) in adults. Several contributory factors, both genetic and environmental, have been identified but others remain elusive. HPFH was found in 10 of 27 members from a Maltese family. We used a genome-wide SNP scan followed by linkage analysis to identify a candidate region on chromosome 19p13.12-13. Sequencing revealed a nonsense mutation in the KLF1 gene, p.K288X, which ablated the DNA-binding domain of this key erythroid transcriptional regulator. Only family members with HPFH were heterozygous carriers of this mutation. Expression profiling on primary erythroid progenitors showed that KLF1 target genes were downregulated in samples from individuals with HPFH. Functional assays suggested that, in addition to its established role in regulating adult globin expression, KLF1 is a key activator of the BCL11A gene, which encodes a suppressor of HbF expression. These observations provide a rationale for the effects of KLF1 haploinsufficiency on HbF levels.

Developmental effect of the XmnI site on Ggamma-globin gene expression among newborn Hb F-Malta-I [Ggamma117(G19)His-->Arg, CAT-->CGT] heterozygotes and adult beta+ -Thalassemia homozygotes.

Hb F-Malta-I [Ggamma117(19)His-->Arg, CAT-->CGT] is a stable and benign variant of Hb F found in 1.8% of Maltese newborn. We studied 120 Hb F-Malta-I heterozygotes and four Hb F-Malta-I homozygotes. The mean proportion of Ggamma-F-Malta-I in Hb F was 0.26 +/- 0.03 for the Hb F-Malta-I heterozygotes and 0.58 +/- 0.06 for the Hb F-Malta-I homozygotes. The Hb F-Malta-I allele was shown to occur on a background of the common Mediterranean haplotype Va [+ + - - - - - + + -]. Furthermore, the common Mediterranean haplotypes Va, IIIb [- + + + - + + + + -], I [+ + - - - - - + + +] and II [- + - + + - + + + +] accounted for most (66.2%) of the wild-type alleles among the tested Hb F-Malta-I heterozygotes. Different genotypes at the 5' epsilon HincII, Ggamma and Agamma HindIII, and 3'psibeta HincII sites (but not at the 5' Ggamma XmnI site) were found to be linked to significant variations in the proportion of Ggamma-F-Malta-I and Ggamma-globins in the Hb F of newborn Hb F-Malta-I heterozygotes. Moreover, the 5' Ggamma XmnI site was found to be associated with variations in Hb F and Ggamma-globin levels in a population of adult Maltese beta-thalassemia (thal) homozygotes. This implies that a determinant linked to the XmnI site which effects Ggamma-globin gene expression is active in anemic adults but not in normal infants.

Molecular genetics of tetrahydrobiopterin (BH4) deficiency in the Maltese population.

Deficient activity of the Dihydropteridine Reductase enzyme (DHPR; EC 1.5.1.34; OMIM 261630) is due to mutations in the Quinoid Dihydropteridine Reductase gene on 4p15.3 (QDPR; RefSeq NM_000320). It results in defective recycling of tetrahydrobiopterin (BH(4)) and homozygotes have a rare form of atypical Hyperphenylalaninaemia and Phenylketonuria (aPKU). The heterozygote frequency in the Maltese population is high at 3.3%. The more recently described and rarer type of BH(4) deficiency due to Sepiapterin Reductase enzyme deficiency (SR; EC 1.1.1.153; OMIM 182125), which presents as an atypical form of Dopa Responsive Dystonia (DRD) [L. Bonafe, B. Thony, J.M. Penzien, B. Czarnecki, N. Blau, Mutations in the sepiapterin reductase gene cause a novel tetrahydrobiopterin-dependent monoamine-neurotransmitter deficiency without hyperphenylalaninemia, Am. J. Hum. Genet. 69 (2001) 269-277; B.R.G. Neville, R. Parascandalo, S. Attard Montalto, R. Farrugia, A.E. Felice, A congenital dopa responsive motor disorder: a Maltese variant due to sepiapterin reductase deficiency, Brain 128 (Pt10) (2005) 2291-2296.] has also been identified at high frequency (4.6%) in this population. Two mutations, the c.68G>A in QDPR (p.G23D), and the new SPR, IVS2-2A>G mutation at the splice site consensus sequence in intron 2 of the Sepiapterin Reductase gene (SPR; RefSeq NM_003124) on 2p14-p12, were found to be the sole causative mutations in all the patients with DHPR deficiency and SR deficiency studied. All parents were heterozygotes for the corresponding mutation and showed no clinical symptoms. Three polymorphisms, c.96C>T (p.A32A), c. 345G>A (p.S115S) and c. 396G>A (p.L132L), have also been identified in the QDPR gene, defining four wild-type frameworks, useful in molecular epidemiology studies. The c. 68G>A mutation in QDPR was found only on framework I, suggesting a founder effect. In contrast no additional sequence diversity was found in the SPR gene whether in wild-type or mutant alleles which is also consistent with a founder effect.

A review of cis-trans interplay between DNA sequences 5' to the (G)gamma- and beta-globin genes among Hb F-Malta-I heterozygotes/homozygotes and beta-thalassemia homozygotes/compound heterozygotes, and the effects of hydroxyurea on the Hb F/F-erythrocyte; the need for large multicenter trials.

The biosynthesis of Hb F in place of the deficient Hb A could be a suitable treatment for beta hemoglobinopathies. Among newborn Hb F-Malta-I heterozygotes, it could be shown that the XmnI sequence alone had little, if any effect on gamma-globin gene expression, but interplay with the (AT)(X)T(Y) sites in cis and in trans may occur. In contrast, while the XmnI sequence is clearly correlated with gamma-globin levels in anemic adult beta-thalassemia (thal) homozygotes, the effect on F-erythrocyte numbers and Hb F/F-erythrocyte appears independent of the (AT)(X)T(Y) sites. Even at levels of hydroxyurea (HU) as low as 1.65 mg/kg/day (vs. 10 mg/kg/day on the high dose regime) it can be shown that although even a small increase of Hb F could be obtained, the effect was rarely translated into an increase in circulating hemoglobin (Hb). In most cases, the elevated Hb F level was dependent on the XmnI sequence and was due to increased numbers of F-erythrocytes or Hb F/F-erythrocyte or both. It seems that the bone marrow of thalassemia homozygotes may be more sensitive to myelosuppression by HU possibly due to medullary inflammation. While the data are consistent with loop models of globin switching mechanisms, there is urgent need for large, hypothesis driven, multicenter trials of molecules that could maintain or re-induce high Hb F levels in beta-thal and subject to genetic and epigenetic constraints including inflammation.