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

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.

GestaltMatcher Database - A global reference for facial phenotypic variability in rare human diseases

The most important factor that complicates the work of dysmorphologists is the significant phenotypic variability of the human face. Next-Generation Phenotyping (NGP) tools that assist clinicians with recognizing characteristic syndromic patterns are particularly challenged when confronted with patients from populations different from their training data. To that end, we systematically analyzed the impact of genetic ancestry on facial dysmorphism. For that purpose, we established the GestaltMatcher Database (GMDB) as a reference dataset for medical images of patients with rare genetic disorders from around the world. We collected 10,980 frontal facial images - more than a quarter previously unpublished - from 8,346 patients, representing 581 rare disorders. Although the predominant ancestry is still European (67%), data from underrepresented populations have been increased considerably via global collaborations (19% Asian and 7% African). This includes previously unpublished reports for more than 40% of the African patients. The NGP analysis on this diverse dataset revealed characteristic performance differences depending on the composition of training and test sets corresponding to genetic relatedness. For clinical use of NGP, incorporating non-European patients resulted in a profound enhancement of GestaltMatcher performance. The top-5 accuracy rate increased by +11.29%. Importantly, this improvement in delineating the correct disorder from a facial portrait was achieved without decreasing the performance on European patients. By design, GMDB complies with the FAIR principles by rendering the curated medical data findable, accessible, interoperable, and reusable. This means GMDB can also serve as data for training and benchmarking. In summary, our study on facial dysmorphism on a global sample revealed a considerable cross ancestral phenotypic variability confounding NGP that should be counteracted by international efforts for increasing data diversity. GMDB will serve as a vital reference database for clinicians and a transparent training set for advancing NGP technology.

A stepwise diagnostic approach for undiagnosed Anemia in children: A model for low-middle income country

BACKGROUND

Reaching a precise diagnosis in rare inherited anemia is extremely difficult and challenging, especially in areas with limited use of genetic studies, which makes undiagnosed anemia a unique clinical entity in tertiary hematology centers. In this study, we aim at plotting a stepwise diagnostic approach in children with undiagnosed anemia while identifying indications for genetic testing.

PATIENTS AND METHODS

A one-year cross-sectional study involved 44 children and adolescents with undiagnosed anemia after undergoing an initial routine panel of investigations. They were classified based on mean corpuscular volume (MCV) into 3 groups: microcytic (n = 19), normocytic (n = 14) and macrocytic (n = 11). An algorithm that included four levels of investigations was devised for each category.

RESULTS

After applying a systematic diagnostic approach, 33 patients (75 %) were diagnosed of whom 7 (15 %) had combined diagnoses, while 11 (25 %) patients remained undiagnosed. Based on the first, second, third and fourth levels of investigations, patients were diagnosed, respectively, as follows: of the 11 patients, 7 were microcytic, 3 normocytic and 1 macrocytic; of the 7 patients, 2 were microcytic, 2 normocytic, and 3 macrocytic; of 10 patients, 5 were microcytic, 4 normocytic and 1 macrocytic; finally, of the 16 patients, 8 were microcytic, 6 normocytic and 2 macrocytic. Numbers recorded appear higher than the actual number of the patients because some of them were diagnosed by more than one level of investigation. The diagnoses obtained in the microcytic group showed hemoglobinopathies, iron refractory iron deficiency anemia (IRIDA), membrane defects, sideroblastic anemia, hypo-transferrinemia, a combined diagnosis of sickle cell trait and pyropoikilocytosis. The diagnoses also showed a combined diagnosis of hereditary spherocytosis (HS) and alpha thalassemia minor, and a combined diagnosis of iron deficiency anemia and beta thalassemia minor, while 15 % remained undiagnosed. In the normocytic group, the diagnosis revealed autosomal recessive (AR) HS, vitamin B12 deficiency, pyruvate kinase deficiency (PKD), congenital dyserythropoietic anemia (CDA) type I, Diamond Blackfan anemia and beta thalassemia major. In addition, it showed a combined diagnosis of AR HS and CDA type II, a combined diagnosis of AR HS and PKD, and a combined diagnosis of dehydrated stomatocytosis (DHS) and G6PD carrier, meanwhile 20 % remained undiagnosed. Finally, the macrocytic group was diagnosed by vitamin B12 deficiency, sideroblastic anemia, PKD, a combined diagnosis of PKD and G6PD deficiency carrier, while 45 % remained undiagnosed.

CONCLUSION

Conducting a stepwise approach with different levels of investigations may help reach the diagnosis of difficult anemia without having to resort to unnecessary investigations. Combined diagnosis is an important cause of undiagnosed anemia, especially in countries with high frequency of consanguinity. The remaining 25 % of the patients continued to be undiagnosed, requiring more sophisticated investigations.

The hemoglobinopathies, molecular disease mechanisms and diagnostics

Hemoglobinopathies are the most common monogenic disorders in the world with an ever increasing global disease burden each year. As most hemoglobinopathies show recessive inheritance carriers are usually clinically silent. Programmes for preconception and antenatal carrier screening, with the option of prenatal diagnosis are considered beneficial in many endemic countries. With the development of genetic tools such as Array analysis and Next Generation Sequencing in addition to state of the art screening at the hematologic, biochemic and genetic level, have contributed to the discovery of an increasing number of rare rearrangements and novel factors influencing the disease severity over the recent years. This review summarizes the basic requirements for adequate carrier screening analysis, the importance of genotype–phenotype correlation and how this may lead to the unrevealing exceptional interactions causing a clinically more severe phenotype in otherwise asymptomatic carriers. A special group of patients are β‐thalassemia carriers presenting with features of β‐thalassemia intermedia of various clinical severity. The disease mechanisms may involve duplicated α‐globin genes, mosaic partial Uniparental Isodisomy of chromosome 11p15.4 where the HBB gene is located or haplo‐insufficiency of a non‐linked gene SUPT5H on chromosome 19q, first described in two Dutch families with β‐thalassemia trait without variants in the HBB gene.

NGS4THAL, a one-stop molecular diagnosis and carrier screening tool for thalassemia and other hemoglobinopathies by next-generation sequencing

Thalassemia is one of the most common genetic diseases and a major health threat worldwide. Accurate, efficient and scalable analysis of next-generation sequencing (NGS) data is much needed for its molecular diagnosis and carrier screening. We developed NGS4THAL, a bioinformatics analysis pipeline analyzing next generation sequencing (NGS) data to detect pathogenic variants for thalassemia and other hemoglobinopathies. NGS4THAL realigns ambiguously mapped NGS reads derived from the homologous hemoglobin gene clusters for accurate detection of point mutations and small insertion/deletions (InDels). It uses a combination of complementary structural variant (SV) detection tools and an inhouse database of control data containing specific SVs to achieve accurate detection of the complex SV types. Detected variants are matched with those in HbVar database, allowing recognition of known pathogenic variants, including disease modifiers. Tested on simulation data, NGS4THAL achieved high sensitivity and specificity. For targeted NGS sequencing data from samples with laboratory-confirmed pathogenic hemoglobin variants, it achieved 100% detection accuracy. Application of NGS4THAL on whole genome sequencing data from unrelated studies revealed thalassemia mutation carrier rates for Hong Kong Chinese and Northern Vietnamese that were consistent with previous reports. NGS4THAL is a highly accurate and efficient molecular diagnosis tool for thalassemia and other hemoglobinopathies based on tailored analysis of NGS data and is potentially scalable for population carrier screening.

Prime Editor 3 Mediated Beta-Thalassemia Mutations of the HBB Gene in Human Erythroid Progenitor Cells

Recently developed Prime Editor 3 (PE3) has been implemented to induce genome editing in various cell types but has not been proven in human hematopoietic stem and progenitor cells. Using PE3, we successfully installed the beta-thalassemia (beta-thal) mutations in the HBB gene in the erythroid progenitor cell line HUDEP-2. We inserted the mCherry reporter gene cassette into editing plasmids, each including the prime editing guide RNA (pegRNA) and nick sgRNA. The plasmids were electroporated into HUDEP-2 cells, and the PE3 modified cells were identified by mCherry expression and collected using fluorescence-activated cell sorting (FACS). Sanger sequencing of the positive cells confirmed that PE3 induced precise beta-thal mutations with editing ratios from 4.55 to 100%. Furthermore, an off-target analysis showed no unintentional edits occurred in the cells. The editing ratios and parameters of pegRNA and nick sgRNA were also analyzed and summarized and will contribute to enhanced PE3 design in future studies. The characterization of the HUDEP-2 beta-thal cells showed typical thalassemia phenotypes, involving ineffective erythropoiesis, abnormal erythroid differentiation, high apoptosis rate, defective alpha-globin colocalization, cell viability deterioration, and ROS resisting deficiency. These HUDEP-2 beta-thal cells could provide ideal models for future beta-thal gene therapy studies.

Molecular Epidemiology and Hematologic Characterization of Thalassemia in Guangdong Province, Southern China

Introduction: About 2% of the population in the world are carriers of the thalassemia gene. Thalassemia is highly prevalent in Southern China, and traditional clinical testing methods would cause missed diagnosis of partial static thalassemia. Here, we reviewed and summarized a set of simple and clinically feasible thalassemia detection protocols adopted by the Prenatal Diagnosis and Reproductive Center of our hospital. Methods: From January 1, 2015, to December 31, 2020, 31 512 peripheral blood samples and 3828 prenatal samples were collected in our study. All the peripheral blood samples were performed through thalassemia screening by routine blood tests and hemoglobin electrophoresis and gene detection. The prenatal diagnosis would be implemented for the fetus if the parents were carriers of the same type of thalassemia. Results: A total of 6137 (19.48%) cases were diagnosed as thalassemia, in which 4749 (15.07%) were α-thalassemia, 1196 (3.80%) were β-thalassemia and 192 (0.61%) were co-inheritance of α- and β-thalassemia. For prenatal samples, 3160 (82.55%) cases were diagnosed as thalassemia, in which 2021 (52.80%) were α-thalassemia, 997 (26.05%) were β-thalassemia and 142 (3.71%) were co-inheritance of α- and β-thalassemia. In addition, we also found five novel mutations, including NC_000016.9:g.223681-227492del3812; HBA1: c.301-31_301-24delCTCGGCCCinsG; HBA2: c.95+7C>T for α-thalassemia and HBB: c.263_276delCACTGAGTGAGCTG; HBB: c.315+143G>A for β-thalassemia. Conclusion: The present study updates the epidemiological characteristics and mutation spectrum of thalassemia in Southern China and demonstrated five novel mutations. Our research provides a reference for clinical diagnosis and treatment, prenatal diagnosis, or reproductive genetic counseling for patients with thalassemia in Guangdong.

The importance of adherence to international standards for depositing open data in public repositories

There has been an important global interest in Open Science, which include open data and methods, in addition to open access publications. It has been proposed that public availability of raw data increases the value and the possibility of confirmation of scientific findings, in addition to the potential of reducing research waste. Availability of raw data in open repositories facilitates the adequate development of meta-analysis and the cumulative evaluation of evidence for specific topics. In this commentary, we discuss key elements about data sharing in open repositories and we invite researchers around the world to deposit their data in them.

Strategies to improve pharmacogenomic-guided treatment options for patients with β-hemoglobinopathies

Drug efficacy and toxicity are closely related to the unique genetic profile of individuals, or pharmacogenomics. Despite the fact that cardiology, psychiatry and oncology are among the clinical specialties in which pharmacogenomics has become a clinical reality, the utility of pharmacogenomics has yet to be demonstrated for several other medical specialties. Over the last 15 years, genomic variants in a number of loci have been shown to be significantly associated with the fetal hemoglobin (HbF) response to hydroxyurea, the only approved drug for HbF induction for sickle cell disease. Here, we provide an update and discuss future challenges to the application of pharmacogenomics to improve therapies for β-hemoglobinopathies in relation to the current pharmacological treatment modalities for those disorders.

A unified model of human hemoglobin switching through single-cell genome editing

Key mechanisms of fetal hemoglobin (HbF) regulation and switching have been elucidated through studies of human genetic variation, including mutations in the HBG1/2 promoters, deletions in the β-globin locus, and variation impacting BCL11A. While this has led to substantial insights, there has not been a unified understanding of how these distinct genetically-nominated elements, as well as other key transcription factors such as ZBTB7A, collectively interact to regulate HbF. A key limitation has been the inability to model specific genetic changes in primary isogenic human hematopoietic cells to uncover how each of these act individually and in aggregate. Here, we describe a single-cell genome editing functional assay that enables specific mutations to be recapitulated individually and in combination, providing insights into how multiple mutation-harboring functional elements collectively contribute to HbF expression. In conjunction with quantitative modeling and chromatin capture analyses, we illustrate how these genetic findings enable a comprehensive understanding of how distinct regulatory mechanisms can synergistically modulate HbF expression.

Genetic mechanisms underlying fetal hemoglobin (HbF) regulation and switching are not fully understood. Here, the authors develop a single-cell genome editing functional assay to model how effects of mutation-harbouring functional elements contribute to HbF expression.

Compounded with hemoglobin Port Phillip and -α4.2 or --SEA deletions were identified in Chinese population

Introduction

Although over 1000 hemoglobin (Hb) variants were identified so far, Hb Port Phillip compound with α‐thalassemia deletion had no reported before.

Methods

Two patients and the associated families from Guangdong province in China were recruited. Hematological parameters were determined by blood routine examination and hemoglobin electrophoresis. Genotyping was performed by Gap‐PCR and Sanger sequencing.

Results

One patient was diagnosed as Hb Port Phillip, while her daughter was compounded with ‐α4.2 deletion, with normal Hb level (150 g/L), mean corpuscular volume (MCV) 108.4 fl and mean corpuscular hemoglobin (MCH) (30.5 pg). Another patient was diagnosed as compound Hb Port Phillip and ‐‐^SEA deletion. This proband presented with more severe α‐thalassemia trait than the patient compounded with ‐α^4.2 deletion, with hemoglobin 80 g/L, MCV 61.7 fl, and MCH 18.7 pg.

Conclusion

Here we first time identified two patients compound with Hb Port Phillip and ‐α^4.2 and ‐‐^SEA deletions, respectively, which had never been reported. Our study widens the genotypes of hemoglobinopathy and provides reference for genetic counselling and prenatal diagnosis in this population.

Analysis of δ-globin gene alleles in Tunisians: description of three new delta-thalassemia mutations

BACKGROUND

Thalassemia is one of the most prevalent worldwide autosomal recessive disorders characterized by a great molecular and clinical expression heterogeneity. Alpha and beta-thalassemia are the main two types observed in case of mutations affecting alpha and beta-globin genes respectively. Delta-thalassemia is noted when mutations occur on the delta-globin gene. In Tunisia, β-thalassemia prevalence is estimated at 2.21% of carriers. However, few reports investigated the delta-globin gene.

OBJECTIVES

In this work, we aimed to perform a molecular study to help define the molecular spectrum of δ-thalassemia mutations in Tunisia.

PATIENTS AND METHODS

The study involved 7558 patients among whom we selected 179 individuals with abnormal HbA₂ values or fractions. Hemoglobin analysis was performed using Capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC). DNA sequencing was performed on ABI prism 310 Genetic Analyzer Applied Biosystems. CUPSAT (Cologne University Protein Stability Analysis Tool) was used for the prediction of protein stability changes upon missense mutations and mutants were modeled via DeepView-SwissPdbViewer and POV-Ray softwares for molecular dynamics simulation studies.

RESULTS

We identified four mutations: HbA2-Yialousa described for the first time in Tunisia ( in 72.72% of cases) and 3 mutations reported for the first time in the world: (i) c.442 T > C Stop147Arg ext 15aa-stop observed in 18.18% of cases, (ii) c.187 G > C (Ala62Pro) noted in 4.54% of cases and (iii) c.93-1G > C found in 4.54% of cases.

CONCLUSION

Our data provide genetic basis that would be especially useful in screening for beta-thalassemia trait during delta-beta thalassemia associations.

Breakpoint characterization of a rare alpha0 -thalassemia deletion using targeted locus amplification on genomic DNA

Introduction

The high‐sequence homology of the α‐globin‐gene cluster is responsible for microhomology‐mediated recombination events during meiosis, resulting in a high density of deletion breakpoints within a 10 kb region. Commonly used deletion detection methods, such as multiplex ligation‐dependent probe amplification (MLPA) and Southern blot, cannot exactly define the breakpoints. This typically requires long‐range PCR, which is not always successful. Targeted locus amplification (TLA) is a targeted enrichment method that can be used to sequence up to 70 kb of neighboring DNA sequences without prior knowledge about the target site.

Methods

Genomic DNA (gDNA) TLA is a technique that folds isolated DNA, ensuring that adjacent loci are in a close spatial proximity. Subsequent digestion and religation form DNA circles that are amplified using fragment‐specific inverse primers, creating a library that is suitable for Illumina sequencing.

Results

Here, we describe the characterization of a rare 16 771 bp deletion, utilizing gDNA TLA with a single inverse PCR primer set on one end of the breakpoint. Primers for breakpoint PCR were designed to confirm the deletion breakpoints and were consequently used to characterize the same deletion in 10 additional carriers sharing comparable hematologic data and similar MLPA results.

Conclusions

The gDNA TLA technology was successfully used to identify deletion breakpoints within the alpha‐globin cluster. The deletion was described only once in an earlier study as the ‐‐^gb, but as it was not registered correctly in the available databases, it was not initially recognized as such.

Genome-based therapeutic interventions for β-type hemoglobinopathies

For decades, various strategies have been proposed to solve the enigma of hemoglobinopathies, especially severe cases. However, most of them seem to be lagging in terms of effectiveness and safety. So far, the most prevalent and promising treatment options for patients with β-types hemoglobinopathies, among others, predominantly include drug treatment and gene therapy. Despite the significant improvements of such interventions to the patient's quality of life, a variable response has been demonstrated among different groups of patients and populations. This is essentially due to the complexity of the disease and other genetic factors. In recent years, a more in-depth understanding of the molecular basis of the β-type hemoglobinopathies has led to significant upgrades to the current technologies, as well as the addition of new ones attempting to elucidate these barriers. Therefore, the purpose of this article is to shed light on pharmacogenomics, gene addition, and genome editing technologies, and consequently, their potential use as direct and indirect genome-based interventions, in different strategies, referring to drug and gene therapy. Furthermore, all the latest progress, updates, and scientific achievements for patients with β-type hemoglobinopathies will be described in detail.

Clinically relevant updates of the HbVar database of human hemoglobin variants and thalassemia mutations

HbVar (http://globin.bx.psu.edu/hbvar) is a widely-used locus-specific database (LSDB) launched 20 years ago by a multi-center academic effort to provide timely information on the numerous genomic variants leading to hemoglobin variants and all types of thalassemia and hemoglobinopathies. Here, we report several advances for the database. We made clinically relevant updates of HbVar, implemented as additional querying options in the HbVar query page, allowing the user to explore the clinical phenotype of compound heterozygous patients. We also made significant improvements to the HbVar front page, making comparative data querying, analysis and output more user-friendly. We continued to expand and enrich the regular data content, involving 1820 variants, 230 of which are new entries. We also increased the querying potential and expanded the usefulness of HbVar database in the clinical setting. These several additions, expansions and updates should improve the utility of HbVar both for the globin research community and in a clinical setting.

Conformational changes of β-thalassemia major hemoglobin and oxidative status of plasma after in vitro exposure to extremely low-frequency electromagnetic fields: An artificial neural network analysis

Electromagnetic fields (EMF) can generate reactive oxygen species and induce oxidative modifications. We investigated the effects of extremely low-frequency electromagnetic fields (ELF-EMF) on oxidative status of plasma and erythrocytes in β-thalassemia major patients and design artificial neural networks (ANN) for evaluating the oxyHb concentration. Blood samples were obtained from age and sex-matched healthy donors (n = 12) and major β-thalassemia patients (n = 12) and subjected to 0.5 and 1 mT and 50 Hz of EMF. Plasma oxidative status was estimated after 1 and 2 h exposure to ELE-EMF. Structural changes of plasma proteins were investigated by Native PAGE and SDS-PAGE. Moreover; multilayer perceptron (MLP) method was applied for designing a feed forward ANN model to predict the impact of these oxidative and antioxidative parameters on oxyHb concentration. Two hour exposure to ELF-EMF induced significant oxidative changes on major β-thalassemia samplesElectrophoretic profiles showed two high molecular weight (HMW) protein aggregates in plasma samples from healthy donors and major β-thalassemia patients. According to our ANN design, the main predictors of oxyHb concentration were optical density of Hb at 542, 340, 569, 630, 577, and 420 nm and metHb and hemichrome (HC) concentration. Accuracy of the proposed ANN model was shown by predicted by observed chart (y = 1.3 + 0.96x, R2 = 0.942), sum of squares errors (SSR), and relative errors (RE). Our results showed the detailed effects of ELF-EMF on Hb structure and oxidative balance of plasma in major β-thalassemia patients and significance of ANN analysis during normal and pathologic conditions.

Modulating gene regulation to treat genetic disorders

Over a thousand diseases are caused by mutations that alter gene expression levels. The potential of nuclease-deficient zinc fingers, TALEs or CRISPR fusion systems to treat these diseases by modulating gene expression has recently emerged. These systems can be applied to modify the activity of gene-regulatory elements - promoters, enhancers, silencers and insulators, subsequently changing their target gene expression levels to achieve therapeutic benefits - an approach termed cis-regulation therapy (CRT). Here, we review emerging CRT technologies and assess their therapeutic potential for treating a wide range of diseases caused by abnormal gene dosage. The challenges facing the translation of CRT into the clinic are discussed.

Roadmap for Establishing Large-Scale Genomic Medicine Initiatives in Low- and Middle-Income Countries

In the post-genomic era, genomic medicine interventions as a key component of personalized medicine and tailored-made health care are greatly anticipated following recent scientific and technological advances. Indeed, large-scale sequencing efforts that explore human genomic variation have been initiated in several, mostly developed, countries across the globe, such as the United States, the United Kingdom, and a few others. Here, we highlight the successful implementation of large-scale national genomic initiatives, namely the Genome of Greece (GoGreece) and the DNA do Brasil (DNABr), aiming to emphasize the importance of implementing such initiatives in developing countries. Based on this experience, we also provide a roadmap for replicating these projects in other low-resource settings, thereby bringing genomic medicine in these countries closer to clinical fruition.

Non-deletional alpha thalassaemia: a review

BACKGROUND

Defective synthesis of the α-globin chain due to mutations in the alpha-globin genes and/or its regulatory elements leads to alpha thalassaemia syndrome. Complete deletion of the 4 alpha-globin genes results in the most severe phenotype known as haemoglobin Bart's, which leads to intrauterine death. The presence of one functional alpha gene is associated with haemoglobin H disease, characterised by non-transfusion-dependent thalassaemia phenotype, while silent and carrier traits are mostly asymptomatic.

MAIN BODY

Clinical manifestations of non-deletional in alpha thalassaemia are varied and have more severe phenotype compared to deletional forms of alpha thalassaemia. Literature for the molecular mechanisms of common non-deletional alpha thalassaemia including therapeutic measures that are necessarily needed for the understanding of these disorders is still in demand. This manuscript would contribute to the better knowledge of how defective production of the α-globin chains due to mutations on the alpha-globin genes and/or the regulatory elements leads to alpha thalassaemia syndrome.

CONCLUSION

Since many molecular markers are associated with the globin gene expression and switching over during the developmental stages, there is a need for increased awareness, new-born and prenatal screening program, especially for countries with high migration impact, and for improving the monitoring of patients with α-thalassaemia.

Documentation of clinically relevant genomic biomarker allele frequencies in the next-generation FINDbase worldwide database

FINDbase (http://www.findbase.org) is a comprehensive data resource recording the prevalence of clinically relevant genomic variants in various populations worldwide, such as pathogenic variants underlying genetic disorders as well as pharmacogenomic biomarkers that can guide drug treatment. Here, we report significant new developments and technological advancements in the database architecture, leading to a completely revamped database structure, querying interface, accompanied with substantial extensions of data content and curation. In particular, the FINDbase upgrade further improves the user experience by introducing responsive features that support a wide variety of mobile and stationary devices, while enhancing computational runtime due to the use of a modern Javascript framework such as ReactJS. Data collection is significantly enriched, with the data records being divided in a Public and Private version, the latter being accessed on the basis of data contribution, according to the microattribution approach, while the front end was redesigned to support the new functionalities and querying tools. The abovementioned updates further enhance the impact of FINDbase, improve the overall user experience, facilitate further data sharing by microattribution, and strengthen the role of FINDbase as a key resource for personalized medicine applications and personalized public health.

Combined use of gap-PCR and next-generation sequencing improves thalassaemia carrier screening among premarital adults in China

Aims

Thalassaemia is one of the most common genetics disorders in the world, especially in southern China. The aim of the present study was to investigate the feasibility of combining the gap-PCR and next-generation sequencing (NGS) for thalassaemia carrier screening in the Chinese population.

Methods

Blood samples were obtained from 944 prepregnancy couples; thalassaemia carrier screening was performed by using a routine haematological method and a combination of gap-PCR and NGS method.

Results

We found that the α thalassaemia carrier rate was 11% (207/1888); the β thalassaemia carrier rate was 3.7% (70/1888); the composite α thalassaemia and β thalassaemia carrier rate was 0.4% (8/1888). We also identified seven novel mutations, including HBA1: c.412A>G, −50 (G>A), HBB: c.*+129T>A, HBB: c.-64G>C, HBB: c.-180G>C, HBB: c.*+5G>A and HBB: c.-113A>G. By comparing the combined gap-PCR and NGS method, the MCV+MCH and HbA2 detection strategy showed a lower sensitivity of 61.05% (105/172) and a higher missed diagnosis ratio of 38.95% (67/172) for α thalassaemia mutations. The sensitivity was improved with the MCV+MCH and HbA2 detection screen when compared with MCV+MCH detection for β thalassaemia (98.51% vs 85.90%).

Conclusions

Our study suggests the combined gap-PCR and NGS method is a cost-effective method for the thalassaemia carrier screening, particularly for the α thalassaemia mutation carriers.

LOVD-DASH: A comprehensive LOVD database coupled with diagnosis and an at-risk assessment system for hemoglobinopathies

Hemoglobinopathies are the most common monogenic disorders worldwide. Substantial effort has been made to establish databases to record complete mutation spectra causing or modifying this group of diseases. We present a variant database which couples an online auxiliary diagnosis and at-risk assessment system for hemoglobinopathies (DASH). The database was integrated into the Leiden Open Variation Database (LOVD), in which we included all reported variants focusing on a Chinese population by literature peer review-curation and existing databases, such as HbVar and IthaGenes. In addition, comprehensive mutation data generated by high-throughput sequencing of 2,087 hemoglobinopathy patients and 20,222 general individuals from southern China were also incorporated into the database. These sequencing data enabled us to observe disease-causing and modifier variants responsible for hemoglobinopathies in bulk. Currently, 371 unique variants have been recorded; 265 of 371 were described as disease-causing variants, whereas 106 were defined as modifier variants, including 34 functional variants identified by a quantitative trait association study of this high-throughput sequencing data. Due to the availability of a comprehensive phenotype-genotype data set, DASH has been established to automatically provide accurate suggestions on diagnosis and genetic counseling of hemoglobinopathies. LOVD-DASH will inspire us to deal with clinical genotyping and molecular screening for other Mendelian disorders.

Checklist for gene/disease-specific variation database curators to enable ethical data management

Databases with variant and phenotype information are essential for advancing research and improving the health and welfare of individuals. These resources require data to be collected, curated, and shared among relevant specialties to maximize impact. The increasing generation of data which must be shared both nationally and globally for maximal effect presents important ethical and privacy concerns. Database curators need to ensure that their work conform to acceptable ethical standards. A Working Group of the Human Variome Project had the task of updating and streamlining ethical guidelines for locus-specific/gene variant database curators. In this article, we present practical and achievable steps which should assist database curators in carrying out their responsibilities within acceptable ethical norms.

Pharmacomicrobiomics informs clinical pharmacogenomics

Aim: Microbiota-host-xenobiotics interactions in humans become of prime interest when clinical pharmacogenomics is to be implemented. Despite the advent of technology, information still needs to be translated into knowledge for optimum patient stratification and disease management. Material & methods: Herein, we mined metagenomic, pharmacometagenomic and pharmacomicrobiomic datasets to map microbiota-host-drugs networks. Results: Datasets were multifaceted and voluminous. Interoperability, data sparsity and scarcity remain a challenge. Mapping microbiota-host-drugs networks allowed the prediction of drug response/toxicity and modulation of the microbiota-host-drugs interplay. Conclusion: Our approach triangulated microbiota, host and drug networks revealing the need for contextual data and open science via microattribution to accelerate knowledge growth. Our findings may serve as a data storehouse for a user-friendly query system, coupled with databanks and databases.

Reactivation of γ-globin in adult β-YAC mice after ex vivo and in vivo hematopoietic stem cell genome editing

Disorders involving β-globin gene mutations, primarily β-thalassemia and sickle cell disease, represent a major target for hematopoietic stem/progenitor cell (HSPC) gene therapy. This includes CRISPR/Cas9-mediated genome editing approaches in adult CD34⁺ cells aimed toward the reactivation of fetal γ-globin expression in red blood cells. Because models involving erythroid differentiation of CD34⁺ cells have limitations in assessing γ-globin reactivation, we focused on human β-globin locus-transgenic (β-YAC) mice. We used a helper-dependent human CD46-targeting adenovirus vector expressing CRISPR/Cas9 (HDAd-HBG-CRISPR) to disrupt a repressor binding region within the γ-globin promoter. We transduced HSPCs from β-YAC/human CD46-transgenic mice ex vivo and subsequently transplanted them into irradiated recipients. Furthermore, we used an in vivo HSPC transduction approach that involves HSPC mobilization and the intravenous injection of HDAd-HBG-CRISPR into β-YAC/CD46-transgenic mice. In both models, we demonstrated efficient target site disruption, resulting in a pronounced switch from human β- to γ-globin expression in red blood cells of adult mice that was maintained after secondary transplantation of HSPCs. In long-term follow-up studies, we did not detect hematological abnormalities, indicating that HBG promoter editing does not negatively affect hematopoiesis. This is the first study that shows successful in vivo HSPC genome editing by CRISPR/Cas9.

Evolution of hemoglobin loci and their regulatory elements

Across the expanse of vertebrate evolution, each species produces multiple forms of hemoglobin in erythroid cells at appropriate times and in the proper amounts. The multiple hemoglobins are encoded in two globin gene clusters in almost all species. One globin gene cluster, linked to the gene NPRL3, is preserved in all vertebrates, including a gene cluster encoding the highly divergent globins from jawless vertebrates. This preservation of synteny may reflect the presence of a powerful enhancer of globin gene expression in the NPRL3 gene. Despite substantial divergence in noncoding DNA sequences among mammals, several epigenetic features of the globin gene regulatory regions are preserved across vertebrates. The preserved features include multiple DNase hypersensitive sites, at least one of which is an enhancer, and binding by key lineage-restricted transcription factors such as GATA1 and TAL1, which in turn recruit coactivators such as P300 that catalyze acetylation of histones. The maps of epigenetic features are strongly correlated with activity in gene regulation, and resources for accessing and visualizing such maps are readily available to the community of researchers and students.

Enhancing Reuse of Data and Biological Material in Medical Research: From FAIR to FAIR-Health

The known challenge of underutilization of data and biological material from biorepositories as potential resources for medical research has been the focus of discussion for over a decade. Recently developed guidelines for improved data availability and reusability-entitled FAIR Principles (Findability, Accessibility, Interoperability, and Reusability)-are likely to address only parts of the problem. In this article, we argue that biological material and data should be viewed as a unified resource. This approach would facilitate access to complete provenance information, which is a prerequisite for reproducibility and meaningful integration of the data. A unified view also allows for optimization of long-term storage strategies, as demonstrated in the case of biobanks. We propose an extension of the FAIR Principles to include the following additional components: (1) quality aspects related to research reproducibility and meaningful reuse of the data, (2) incentives to stimulate effective enrichment of data sets and biological material collections and its reuse on all levels, and (3) privacy-respecting approaches for working with the human material and data. These FAIR-Health principles should then be applied to both the biological material and data. We also propose the development of common guidelines for cloud architectures, due to the unprecedented growth of volume and breadth of medical data generation, as well as the associated need to process the data efficiently.

Structure and function of haemoglobins

Haemoglobin (Hb) is widely known as the iron-containing protein in blood that is essential for O₂ transport in mammals. Less widely recognised is that erythrocyte Hb belongs to a large family of Hb proteins with members distributed across all three domains of life-bacteria, archaea and eukaryotes. This review, aimed chiefly at researchers new to the field, attempts a broad overview of the diversity, and common features, in Hb structure and function. Topics include structural and functional classification of Hbs; principles of O₂ binding affinity and selectivity between O₂/NO/CO and other small ligands; hexacoordinate (containing bis-imidazole coordinated haem) Hbs; bacterial truncated Hbs; flavohaemoglobins; enzymatic reactions of Hbs with bioactive gases, particularly NO, and protection from nitrosative stress; and, sensor Hbs. A final section sketches the evolution of work on the structural basis for allosteric O₂ binding by mammalian RBC Hb, including the development of newer kinetic models. Where possible, reference to historical works is included, in order to provide context for current advances in Hb research.

Whole transcriptome analysis of human erythropoietic cells during ontogenesis suggests a role of VEGFA gene as modulator of fetal hemoglobin and pharmacogenomic biomarker of treatment response to hydroxyurea in β-type hemoglobinopathy patients

BACKGROUND

Human erythropoiesis is characterized by distinct gene expression profiles at various developmental stages. Previous studies suggest that fetal-to-adult hemoglobin switch is regulated by a complex mechanism, in which many key players still remain unknown. Here, we report our findings from whole transcriptome analysis of erythroid cells, isolated from erythroid tissues at various developmental stages in an effort to identify distinct molecular signatures of each erythroid tissue.

RESULTS

From our in-depth data analysis, pathway analysis, and text mining, we opted to focus on the VEGFA gene, given its gene expression characteristics. Selected VEGFA genomic variants, identified through linkage disequilibrium analysis, were explored further for their association with elevated fetal hemoglobin levels in β-type hemoglobinopathy patients. Our downstream analysis of non-transfusion-dependent β-thalassemia patients, β-thalassemia major patients, compound heterozygous sickle cell disease/β-thalassemia patients receiving hydroxyurea as fetal hemoglobin augmentation treatment, and non-thalassemic individuals indicated that VEGFA genomic variants were associated with disease severity in β-thalassemia patients and hydroxyurea treatment efficacy in SCD/β-thalassemia compound heterozygous patients.

CONCLUSIONS

Our findings suggest that VEGFA may act as a modifier gene of human globin gene expression and, at the same time, serve as a genomic biomarker in β-type hemoglobinopathy disease severity and hydroxyurea treatment efficacy.

Molecular basis of α-thalassemia

α-Thalassemia is an inherited, autosomal recessive, disorder characterized by a microcytic hypochromic anemia. It is one of the most common monogenic gene disorders in the world population. The clinical severity varies from almost asymptomatic, to mild microcytic hypochromic, and to a lethal hemolytic condition, called Hb Bart's Hydrops Foetalis Syndrome. The molecular basis are usually deletions and less frequently, point mutations affecting the expression of one or more of the duplicated α-genes. The clinical variation and increase in disease severity is directly related to the decreased expression of one, two, three or four copies of the α-globin genes. Deletions and point mutations in the α-globin genes and their regulatory elements have been studied extensively in carriers and patients and these studies have given insight into the α-globin genes are regulated. By looking at naturally occurring deletions and point mutations, our knowledge of globin-gene regulation and expression will continue to increase and will lead to new targets of therapy.

Increasing the involvement of diverse populations in genomics-based health care-lessons from haemoglobinopathies

Integrating genomic medicine into health care delivery poses significant challenges to health professionals. To draw clinical benefit from genomic information, there is a need to build an evidence-based relationship between genotype and the physical expression of that genomic information. The work presented here uses preliminary work in the field of haemoglobinopathies to address two important challenges: to ensure that health care professionals in low- and middle-income countries are actively involved in the processes that will support genomic medicine, and that equity and diversity concerns are met so that clinical services can have relevance across all population and sub-population groups. Haemoglobinopathies provide an opportunity for gaining a better understanding of how long-standing genetic knowledge can be leveraged to determine if genomic-based services can be beneficial in low-resource settings. The Global Globin 2020 Challenge (GG2020) is an international initiative that uses haemoglobinopathies as an entry point to achieving growth in the quality and quantity of curated inputs into internationally recognised databases, harmonising the sharing of variant information within and between countries for better health care delivery and ensuring that storing, curation and sharing of variant information become an integral part of health care. Early findings from GG2020 indicate that paying attention to population diversity is an integral part of prevention and control of haemoglobinopathies.

Rapid Targeted Next-Generation Sequencing Platform for Molecular Screening and Clinical Genotyping in Subjects with Hemoglobinopathies

Hemoglobinopathies are among the most common autosomal-recessive disorders worldwide. A comprehensive next-generation sequencing (NGS) test would greatly facilitate screening and diagnosis of these disorders. An NGS panel targeting the coding regions of hemoglobin genes and four modifier genes was designed. We validated the assay by using 2522 subjects affected with hemoglobinopathies and applied it to carrier testing in a cohort of 10,111 couples who were also screened through traditional methods. In the clinical genotyping analysis of 1182 β-thalassemia subjects, we identified a group of additional variants that can be used for accurate diagnosis. In the molecular screening analysis of the 10,111 couples, we detected 4180 individuals in total who carried 4840 mutant alleles, and identified 186 couples at risk of having affected offspring. 12.1% of the pathogenic or likely pathogenic variants identified by our NGS assay, which were undetectable by traditional methods. Compared with the traditional methods, our assay identified an additional at-risk 35 couples. We describe a comprehensive NGS-based test that offers advantages over the traditional screening/molecular testing methods. To our knowledge, this is among the first large-scale population study to systematically evaluate the application of an NGS technique in carrier screening and molecular diagnosis of hemoglobinopathies.

Barriers to clinical adoption of next-generation sequencing: a policy Delphi panel's solutions

Aim

Identify solutions to the most important policy barriers to the clinical adoption of next-generation sequencing.

Materials & methods

Four-round modified policy Delphi with a multistakeholder panel of 48 experts. The panel deliberated policy solutions to (previously reported) challenges deemed most important to address.

Results

The group advocated using consensus panels to promote consistency in payer policies and to standardize test reporting, and favored making genomic data-sharing a condition of regulatory clearance, certification, or accreditation processes. They were split on the role of US FDA.

Conclusion

Panelists found common ground on solutions for health plan coverage policy consistency, data-sharing, and standardizing reporting, but were sharply divided on the role of the FDA in mitigating risks to patients.

Molecular basis of β thalassemia and potential therapeutic targets

The remarkable phenotypic diversity of β thalassemia that range from severe anemia and transfusion-dependency, to a clinically asymptomatic state exemplifies how a spectrum of disease severity can be generated in single gene disorders. While the genetic basis for β thalassemia, and how severity of the anemia could be modified at different levels of its pathophysiology have been well documented, therapy remains largely supportive with bone marrow transplant being the only cure. Identification of the genetic variants modifying fetal hemoglobin (HbF) production in combination with α globin genotype provide some prediction of disease severity for β thalassemia but generation of a personalized genetic risk score to inform prognosis and guide management requires a larger panel of genetic modifiers yet to be discovered. Nonetheless, genetic studies have been successful in characterizing the key variants and pathways involved in HbF regulation, providing new therapeutic targets for HbF reactivation. BCL11A has been established as a quantitative repressor, and progress has been made in manipulating its expression using genomic and gene-editing approaches for therapeutic benefits. Recent discoveries and understanding in the mechanisms associated with ineffective and abnormal erythropoiesis have also provided additional therapeutic targets, a couple of which are currently being tested in clinical trials.

Towards a global cancer knowledge network: dissecting the current international cancer genomic sequencing landscape

BACKGROUND

While next generation sequencing has enhanced our understanding of the biological basis of malignancy, current knowledge on global practices for sequencing cancer samples is limited. To address this deficiency, we developed a survey to provide a snapshot of current sequencing activities globally, identify barriers to data sharing and use this information to develop sustainable solutions for the cancer research community.

METHODS

A multi-item survey was conducted assessing demographics, clinical data collection, genomic platforms, privacy/ethics concerns, funding sources and data sharing barriers for sequencing initiatives globally. Additionally, respondents were asked as to provide the primary intent of their initiative (clinical diagnostic, research or combination).

RESULTS

Of 107 initiatives invited to participate, 59 responded (response rate = 55%). Whole exome sequencing (P = 0.03) and whole genome sequencing (P = 0.01) were utilized less frequently in clinical diagnostic than in research initiatives. Procedures to identify cancer-specific variants were heterogeneous, with bioinformatics pipelines employing different mutation calling/variant annotation algorithms. Measurement of treatment efficacy varied amongst initiatives, with time on treatment (57%) and RECIST (53%) being the most common; however, other parameters were also employed. Whilst 72% of initiatives indicated data sharing, its scope varied, with a number of restrictions in place (e.g. transfer of raw data). The largest perceived barriers to data harmonization were the lack of financial support (P < 0.01) and bioinformatics concerns (e.g. lack of interoperability) (P = 0.02). Capturing clinical data was more likely to be perceived as a barrier to data sharing by larger initiatives than by smaller initiatives (P = 0.01).

CONCLUSIONS

These results identify the main barriers, as perceived by the cancer sequencing community, to effective sharing of cancer genomic and clinical data. They highlight the need for greater harmonization of technical, ethical and data capture processes in cancer sample sequencing worldwide, in order to support effective and responsible data sharing for the benefit of patients.

Comparative genomics of canine hemoglobin genes reveals primacy of beta subunit delta in adult carnivores

Background

The main function of hemoglobin (Hb) is to transport oxygen in the circulation. It is among the most highly studied proteins due to its roles in physiology and disease, and most of our understanding derives from comparative research. There is great diversity in Hb gene evolution in placental mammals, mostly in the repertoire and regulation of the β-globin subunits. Dogs are an ideal model in which to study Hb genes because: 1) they are members of Laurasiatheria, our closest relatives outside of Euarchontoglires (including primates, rodents and rabbits), 2) dog breeds are isolated populations with their own Hb-associated genetics and diseases, and 3) their high level of health care allows for development of biomedical investigation and translation.

Results

We established that dogs have a complement of five α and five β-globin genes, all of which can be detected as spliced mRNA in adults. Strikingly, HBD, the allegedly-unnecessary adult β-globin protein in humans, is the primary adult β-globin in dogs and other carnivores; moreover, dogs have two active copies of the HBD gene. In contrast, the dominant adult β-globin of humans, HBB, has high sequence divergence and is expressed at markedly lower levels in dogs. We also showed that canine HBD and HBB genes are complex chimeras that resulted from multiple gene conversion events between them. Lastly, we showed that the strongest signal of evolutionary selection in a high-altitude breed, the Bernese Mountain Dog, lies in a haplotype block that spans the β-globin locus.

Conclusions

We report the first molecular genetic characterization of Hb genes in dogs. We found important distinctions between adult β-globin expression in carnivores compared to other members of Laurasiatheria. Our findings are also likely to raise new questions about the significance of human HBD. The comparative genomics of dog hemoglobin genes sets the stage for diverse research and translation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3513-0) contains supplementary material, which is available to authorized users.

Genetic Basis and Genetic Modifiers of β-Thalassemia and Sickle Cell Disease

β-thalassemia and sickle cell disease (SCD) are prototypical Mendelian single gene disorders, both caused by mutations affecting the adult β-globin gene. Despite the apparent genetic simplicity, both disorders display a remarkable spectrum of phenotypic severity and share two major genetic modifiers-α-globin genotype and innate ability to produce fetal hemoglobin (HbF, α₂γ₂).This article provides an overview of the genetic basis for SCD and β-thalassemia, and genetic modifiers identified through phenotype correlation studies. Identification of the genetic variants modifying HbF production in combination with α-globin genotype provide some prediction of disease severity for β-thalassemia and SCD but generation of a personalized genetic risk score to inform prognosis and guide management requires a larger panel of genetic modifiers yet to be discovered.Nonetheless, genetic studies have been successful in characterizing some of the key variants and pathways involved in HbF regulation, providing new therapeutic targets for HbF reactivation.

Emerging cellular and gene therapies for congenital anemias

Congenital anemias comprise a group of blood disorders characterized by a reduction in the number of peripherally circulating erythrocytes. Various genetic etiologies have been identified that affect diverse aspects of erythroid physiology and broadly fall into two main categories: impaired production or increased destruction of mature erythrocytes. Current therapies are largely focused on symptomatic treatment and are often based on transfusion of donor-derived erythrocytes and management of complications. Hematopoietic stem cell transplantation represents the only curative option currently available for the majority of congenital anemias. Recent advances in gene therapy and genome editing hold promise for the development of additional curative strategies for these blood disorders. The relative ease of access to the hematopoietic stem cell compartment, as well as the possibility of genetic manipulation ex vivo and subsequent transplantation in an autologous manner, make blood disorders among the most amenable to cellular therapies. Here we review cell-based and gene therapy approaches, and discuss the limitations and prospects of emerging avenues, including genome editing tools and the use of pluripotent stem cells, for the treatment of congenital forms of anemia. © 2016 Wiley Periodicals, Inc.

Expanded national database collection and data coverage in the FINDbase worldwide database for clinically relevant genomic variation allele frequencies

FINDbase (http://www.findbase.org) is a comprehensive data repository that records the prevalence of clinically relevant genomic variants in various populations worldwide, such as pathogenic variants leading mostly to monogenic disorders and pharmacogenomics biomarkers. The database also records the incidence of rare genetic diseases in various populations, all in well-distinct data modules. Here, we report extensive data content updates in all data modules, with direct implications to clinical pharmacogenomics. Also, we report significant new developments in FINDbase, namely (i) the release of a new version of the ETHNOS software that catalyzes development curation of national/ethnic genetic databases, (ii) the migration of all FINDbase data content into 90 distinct national/ethnic mutation databases, all built around Microsoft's PivotViewer (http://www.getpivot.com) software (iii) new data visualization tools and (iv) the interrelation of FINDbase with DruGeVar database with direct implications in clinical pharmacogenomics. The abovementioned updates further enhance the impact of FINDbase, as a key resource for Genomic Medicine applications.

A European Spectrum of Pharmacogenomic Biomarkers: Implications for Clinical Pharmacogenomics

Pharmacogenomics aims to correlate inter-individual differences of drug efficacy and/or toxicity with the underlying genetic composition, particularly in genes encoding for protein factors and enzymes involved in drug metabolism and transport. In several European populations, particularly in countries with lower income, information related to the prevalence of pharmacogenomic biomarkers is incomplete or lacking. Here, we have implemented the microattribution approach to assess the pharmacogenomic biomarkers allelic spectrum in 18 European populations, mostly from developing European countries, by analyzing 1,931 pharmacogenomics biomarkers in 231 genes. Our data show significant inter-population pharmacogenomic biomarker allele frequency differences, particularly in 7 clinically actionable pharmacogenomic biomarkers in 7 European populations, affecting drug efficacy and/or toxicity of 51 medication treatment modalities. These data also reflect on the differences observed in the prevalence of high-risk genotypes in these populations, as far as common markers in the CYP2C9, CYP2C19, CYP3A5, VKORC1, SLCO1B1 and TPMT pharmacogenes are concerned. Also, our data demonstrate notable differences in predicted genotype-based warfarin dosing among these populations. Our findings can be exploited not only to develop guidelines for medical prioritization, but most importantly to facilitate integration of pharmacogenomics and to support pre-emptive pharmacogenomic testing. This may subsequently contribute towards significant cost-savings in the overall healthcare expenditure in the participating countries, where pharmacogenomics implementation proves to be cost-effective.

Hb Olivet (HBA1: C.40G > A; p.Ala14Thr), a Novel Silent Hemoglobin Variant in Two Families of Distinct Origin

We report two families, members of which are carriers of a novel hemoglobin (Hb) variant that was named Hb Olivet [α13(A11)Ala→Thr (α1) (GCC > ACC); HBA1: c.40G > A; p.Ala14Thr]. The analysis of these cases allowed a clear description of this anomaly that behaves as a silent Hb. In the first family, of Portuguese ethnicity living in France, the proband, a 24-year-old male and his 57-year-old mother, both appeared to be carriers. The son presented with borderline mean corpuscular volume (MCV), while the mother was normocytic and normochromic. Hemoglobin separation on capillary electrophoresis (CE) was normal, while a slightly asymmetric peak was observed on high performance liquid chromatography (HPLC). In a second family, originally from Surinam but living in The Netherlands, the proband, a 6-year-old girl, showed a mild microcytosis at low ferritin levels. The abnormal Hb was inherited from the mother who was clearly iron depleted, was not present in the sister and brother of the proband. The microcytic hypochromic anemia was only shown in two out of a total of four carriers. It therefore seems likely that iron depletion is causative as two carriers are completely normal. Characterization and genotype/phenotype correlation are briefly described.