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.

Universal screening for hemoglobinopathies in today's multi-ethnic societies: How and when

Increasing multi-ethnicity in countries endemic or non-endemic for hemoglobinopathies has brought fundamental changes to the screening strategies for these traits. While in the past pre-screening on microcytosis was a reasonable method to economize upon follow up analysis, selecting low mean corpuscular volume means today missing all those normocytic carriers of common traits associated with severe conditions. Therefore, blood count should not be considered as a pre-selection tool but as additional information to be used for the interpretation of the provisional results, obtained by routine high throughput separation and measurement of the hemoglobin (Hb) fractions. Moreover, the moment of screening should be well planned depending on the social and cultural situation. Screening for genetic diseases in a modern multi-ethnic society should be offered to couples seeking progeny when both partners are more likely to be equally concerned with the good health of their children. In several societies screening before marriage and changing partner choice is culturally accepted. However, new generations are bound to disagree with these more or less imposed conditions and may decide not to renounce the choice of their partner asking for other preventive methods. In addition, a carrier state during pre-marital screening may in some cultures stigmatize the carrier, mostly the female with adverse social consequences. Therefore, screening for hemoglobinopathies early in pregnancy is the most sensible alternative in modern countries. Adding hemoglobinopathies to the routine rhesus screening using a simple separation of the Hb fractions on dedicated devices (high performance liquid chromatography or capillary electrophoresis) will virtually identify all female carriers of all common traits responsible for the severe conditions mainly sickle cell disease and thalassemia major in time for partner analysis, counseling and primary prevention.

Homozygosity for the AATAAA > AATA- - Polyadenylation Site Mutation on the α2-Globin Gene Causing Transfusion-Dependent Hb H Disease in an Iranian Patient: A Case Report

We describe a case of Hb H disease associated with homozygosity for a two nucleotide deletion in the polyadenylation signal of the α2-globin gene (HBA2: c.*93_*94delAA). The patient, a 27-year-old son of a consanguineous couple, needs regular blood transfusions every 6 months.

Haplotypes, Sub-Haplotypes and Geographical Distribution in Omani Patients with Sickle Cell Disease

Despite the fact that patients homozygous for the sickle cell disease (SCD) mutation have an identical genotype, the severity of the disease can be extremely variable. The hemoglobin (Hb) S mutation has been described on five different haplotypes with different clinical expression. Identifying the genotypes, haplotypes and sub-haplotypes of the β gene cluster in Oman needs to be studied in more details to establish a correlation between the genotype/haplotype and phenotype diversity observed in SCD patients for prognostic purposes, accurate diagnosis and thus planning for the best tailored treatment. We have investigated 125 HbS homozygotes from different parts of Oman and determined their haplotypes and sub-haplotypes and correlated this to the hematological and clinical expression. We have found 11 haplotype combinations differently distributed in the country, with the Asian/Asian HbS haplotype being the most predominant. Sub-haplotypes was only found among patients with CAR/OmanI haplotype. As expected, the correlation between haplotypes, sub-haplotypes and disease severity was mainly associated with HbF expression. Our study on haplotype/phenotype correlation has shown which major haplotypes occur in the different regions of Oman. Furthermore, neither the haplotype or sub-haplotype nor the HbF alone appeared to be fully associable with the variable clinical phenotypes. External factors do occur and are associated with the expression of the disease.尽管镰状细胞突变病（SCD）患者拥有相同的基因类型，但患者的病患程度却大相径庭。血红蛋白（Hb）S突变有五种不同的单体型，各种类型在临床表现上也不相同。为了识别在阿曼地区β基因簇的基因型、单体型，亚单体型，需要研究更多以SCD患者预后为目的，关于其观察到的基因型、单体型，表型多样性之间联系的更多细节，以便作出准确的诊断，为各个患者量身制定治疗方案。我们研究了125个来自阿曼不同地区的HbS纯合体，并确认了它们的单体型和亚单体型血液学上的临床表现。我们已找到了该国家11个单体型组合的不同分布，其中以亚洲/亚洲HbS单体型为主要类型。亚单体型只在CAR/OMANI单体型患者中被发现。正如之前所料，单体型、亚单体型和病患程度之间的联系主要与HbF表现相关。我们关于单体型和亚单体型之间联系的研究显示出了阿曼地区最为主要的单体类型。此外，无论是单体型、亚单体型还是HbF，都被证明与该疾病不同的临床表现没有紧密的联系。外部因素是该疾病不同表现的致因。

Hb Lansing (HBA2: c.264C > G) and a new β promoter transversion [-52 (G > T)]: an attempt to define the phenotype of two mutations found in the Omani population

We report two examples showing how problematic it can be to define the phenotype of new or rare globin genes mutations. We describe two mutations observed for the first time in the Omani population: the first was found in the consanguineous parents of a deceased newborn with hepatomegaly, cardiomegaly and severe hemolytic anemia, putatively homozygous for the rare Hb Lansing (HBA2: c.264C > G) variant. The second is a novel β-globin gene promoter mutation [-52 (G > T)] observed in four independent patients. Two with borderline/elevated Hb A2, α-thalassemia (α-thal) and hypochromic red cell indices, and two heterozygotes for Hb S (HBB: c.20A > T), α-thal and with Hb A/Hb S ratios possibly indicating a very mild β(+)-thalassemia (β(+)-thal) mutation.

Broader spectrum of β-thalassemia mutations in Oman: regional distribution and comparison with neighboring countries

The objective of this study was to expand and study the molecular spectrum of β-thalassemia (β-thal) mutations in Oman by examining cases from seven different regions and comparing the prevalence with neighboring countries. A total of 446 cases of β hemoglobinopathies was obtained and analyzed to determine the frequency and distribution of the different β alleles. The molecular spectrum of β-thal in Oman revealed the presence of 32 mutations from different origins and 11 alleles are reported for the first time in the Omani population. The wide heterogeneous spectrum of β-thal mutations found can be associated with the history of trade and migration as well as the past domination from other countries. The presented data will facilitate the development of a comprehensive prevention strategy in Oman.

Primary Prevention of Hemoglobinopathies by Prenatal Diagnosis and Selective Pregnancy Termination in a Muslim Country: Oman

Hemoglobinopathies (HBP) are the most common genetic disorder in Oman and are in need of prevention programs due to the high incidence of β-thalassemia major and sickle cell disease. Prenatal diagnosis (PD) and selective pregnancy termination is shown to be the most effective prevention tool for the control of HBP. However, PD is not available in Oman thus far because abortion is subject to religious, cultural and ethical issues. We have examined the attitude of a number of Omani HBP carrier couples towards prenatal diagnosis and selective abortion. We have interviewed 35 couples at risk visiting the main premarital clinic in Muscat between Jan 2011 and Jan 2012. Couples were interviewed using a pre-structured questionnaire. The majority would have accepted prenatal diagnosis (94%) if the service would be available in the country but pregnancy termination was greatly influenced by religious values.

Molecular spectrum of α-globin gene defects in the Omani population

We describe the molecular characterization of α-globin gene defects in a cohort of 634 Omani patients. A total of 21 different α gene mutations were found in 484 subjects. Overall, we identified three different large deletions, three small deletions, 11 point mutations [two on the α2 polyadenylation signal (polyA) (HBA2: c.*94A>G), and nine α chain variants], three ααα(anti 3.7) triplication, a 21 nucleotide (nt) duplication on the α1 gene and two novel (presumed) polymorphisms on the α 3.7 kb hybrid gene, namely -5 (C>T) and +46 (C>A). Of these defects, 15 have not been previously reported in the Omani population. This large heterogeneity of α-thalassemia (α-thal) observed in the Omani population could be expected in neighboring Arab countries. The high frequency of α-thal, solely or in association with β-globin gene defects, emphasize the necessity of adding α-thal testing to pre marital programs for accurate genetic counseling.

Providing Appropriate Genetic Information to Healthy Multi-Ethnic Carriers of Hemoglobinopathy in The Netherlands

The aims of this study are: (i) to enquire whether informing healthy hemoglobinopathy carriers about their condition is a welcome initiative in The Netherlands; (ii) to study whether using information letters and thorough explanation is associated with presence or absence of undesired feelings or emotions. We have approached 100 multi-ethnic carriers previously diagnosed in our lab. All subjects had previously received our information letter through their physician who was supposed to have provided an explanation of the letter if required. We have enquired whether the subjects had experienced negative or positive emotions after receiving our diagnosis and explanation and to which degree, if they were sufficiently informed and satisfied and if they would have considered prevention in case of risk. The rate negative versus positive feelings was calculated using a numerical distribution. We have registered negative feelings in a rate that was directly proportional to the lack of information. While the number of registered negative feelings in well-informed carriers was very low it was more present in badly informed. Nevertheless, all participants found carrier information a welcome initiative and over 80% of them declared to be in favor of prenatal diagnosis in case of risk. Carrier information is essential for an informed reproductive choice and is welcome in a multi-ethnic society. Unfortunately, information is not always consequently provided and should therefore be imbedded in the ongoing national screening for Rhesus and infectious diseases available to all women in early pregnancy.

Characterization of Hb Calvino (HBB: c.406G > A): a new silent β-globin gene variant found in coexistence with α-thalassemia in a family of African origin

We report a new silent β-globin gene variant found in a family from Angola living in the north eastern Italian city of Ferrara. The probands, two young sisters, presented with hematological parameters compatible with a β-thalassemia (β-thal) minor but with normal Hb A₂ levels and normal hemoglobin (Hb) separation on high performance liquid chromatography (HPLC). Molecular analyses revealed a homozygosity for the common -α(3.7) (rightward) deletion and heterozygosity for a novel transition (GCT > ACT) at codon 135 of the β-globin gene, leading to an Ala → Thr single amino acid substitution that was inherited from the healthy father.

Known and new δ-globin gene mutations and other factors influencing Hb A2 measurement in the Omani population

Although δ-thalassemia (δ-thal) is not categorized as a severe disease, it is essential to know the molecular spectrum of the δ gene mutations frequently occurring in specific areas, particularly if these areas are characterized by a high rate of β-thalassemia (β-thal) such as Oman. This is because coinherited δ-globin gene defects can interfere with the basic diagnosis of a β-thal carrier when this is based upon the measurement of the Hb A2 only. Because of that, we have investigated 33 patients with low Hb A2 levels, collected from different hospitals in Oman. Some cases had a second Hb A2 fraction, while others had only significantly lower Hb A2 levels. Among these patients, 20 did carry a δ-globin gene mutation, the rest were carriers of α thalassemia (α-thal) defects or could be iron depleted or both. In total, eight different known mutations and two novel δ variants were found. The characterization of the δ-globin gene mutation spectrum will improve carrier diagnostics and genetic counseling in the Omani population screened for β-thal.

Genetic epidemiology and preventive healthcare in multiethnic societies: the hemoglobinopathies

Healthy carriers of severe Hemoglobinopathies are usually asymptomatic and only efficiently detected through screening campaigns. Based upon epidemiological data, screenings have been offered for decades to populations of endemic Southern Europe for primary prevention of Thalassemia Major, while for many populations of the highly endemic African and Asian countries prevention for Sickle Cell Disease and Thalassemia Major is mainly unavailable. The massive migrations of the last decades have brought many healthy carriers of these diseases to live and reproduce in non-endemic immigration areas changing the epidemiological pattern of the local recessive diseases and bringing an urgent need for treatment and primary prevention in welfare countries. Nonetheless, no screening for an informed reproductive choice is actively offered by the healthcare systems of most of these welfare countries. As a consequence more children affected with severe Hemoglobinopathies are born today in the immigration countries of Northern Europe than in the endemic Southern European area. Following the Mediterranean example, some countries like the UK and The Netherlands have been offering early pregnancy carrier screening at different levels and/or in specific areas but more accessible measures need to be taken at the national level in all immigration countries. Identification of carriers using simple and inexpensive methods should be included in the Rhesus and infectious diseases screening which is offered early in pregnancy in most developed countries. This would allow identification of couples at risk in time for an informed choice and for prenatal diagnosis if required before the first affected child is born.

[Haemoglobinopathy in the 21st century: incidence, diagnosis and heel prick screening]

OBJECTIVE

To determine the incidence of severe haemoglobinopathy, to evaluate the effect of heel prick screening, and to identify those children who do not benefit from this early diagnosis.

DESIGN

Prospective descriptive study.

METHOD

Registration of all symptomatic and asymptomatic children who between 2003-2009 were newly diagnosed with the a severe form of a hereditary disorder concerning the formation of the alpha haemoglobin chain (HbH disease), or the beta haemoglobin chain (sickle cell disease or beta thalassaemia major) in the Netherlands. Registration was done by collecting anonymised reports from the Dutch Paediatric Surveillance Unit and TNO, and by additional questionnaires.

RESULTS

During the study period, 48 children (range: 36-76) per year were diagnosed with severe haemoglobinopathy. The overall incidence was 2.5 per 10,000 live births. The incidence of sickle cell disease diagnosed by heel prick screening was 2.1 per 10,000 live births and of thalassaemia major 0.6 per 10,000 live births. In 7% of the children with sickle cell disease who were diagnosed without any form of screening, the diagnosis was made on (a life threatening) infection. Twenty-two percent of the children with a severe form of haemoglobinopathy were not born in the Netherlands. The parents of almost half of the children with sickle cell disease originally came from West- or Central Africa. The parents of children with thalassaemia major were mainly from Morocco or various Asiatic countries.

CONCLUSION

The number of children with severe haemoglobinopathy in the Netherlands has trebled since 1992. In order for all children to benefit from early diagnosis and preventive treatment, it is advisable that children who originate from risk areas should be tested for haemoglobinopathy when they first arrive in the Netherlands.

After the introduction into the national newborn screening program: who is receiving genetic counseling for hemoglobinopathies in the Netherlands?

OBJECTIVE

Universal newborn screening for hemoglobinopathies started in The Netherlands in 2007. Herewith severe conditions, such as sickle cell disease, β-thalassemia major and hemoglobin H disease are putatively identified. Additionally, at least 1,800 carriers of hemoglobin variants associated with severe conditions in homozygote or compound heterozygote forms are identified yearly. Thus far, approximately 60 patients and 800 healthy sickle cell (HbS) carriers are reported each year among 180,000 newborns. Results are sent to the general practitioner with the recommendation to inform and diagnose both parents of the healthy carriers to exclude genetic risk, while patients and their parents are referred directly to a pediatrician. This study was performed to determine how often parents of identified carriers and affected newborns are seen in genetic centers for counseling.

METHODS

In this retrospective study, we collected anonymized data from 7 of the 8 Dutch clinical genetic centers from January 1, 2007, until December 31, 2010.

RESULTS

After an initial general increase in total counseling intakes, a decline was noticed in the third year, while the requests for prenatal diagnoses remained relatively stable. In 2007 and 2013, genetic counselors were asked for self-reported knowledge. They found hemoglobinopathy counseling complex, but by 2013, they indicated they had acquired sufficient knowledge on most hemoglobinopathy aspects.

CONCLUSION

We could not observe a significant increase in genetic counseling for hemoglobinopathy after its introduction into newborn screening. Although 120 HbS carriers and 60 patients are expected to be born from couples at risk annually, only 33 at risk couples out of 540 families of diagnosed newborns received optimal care and information at a genetics center in 4 years.

Exploring the use of expanded erythroid cells for autologous transfusion for anemia of prematurity

BACKGROUND

Autologous cord blood (CB) red blood cells (RBCs) can partly substitute transfusion needs in premature infants suffering from anemia. To explore whether expanded CB cells could provide additional autologous cells suitable for transfusion, we set up a simple one-step protocol to expand premature CB cells.

STUDY DESIGN AND METHODS

CB buffy coat cells and isolated CD34-positive (CD34(pos) ) cells from premature and full-term CB and adult blood were tested with several combinations of growth factors while omitting xenogeneic proteins from the culture medium. Cell differentiation was analyzed serially during 21 days using flow cytometry, progenitor assays, and high-performance liquid chromatography.

RESULTS

Expanded CB buffy coat cells resulted in a threefold higher number of erythroblasts than the isolated CD34(pos) cells. However, the RBCs contaminating the buffy coat remained present during the culture with uncertain quality. Premature and full-term CB CD34(pos) cells had similar fold expansion capacity and erythroid differentiation. With the use of interleukin-3, stem cell factor, and erythropoietin, the fold increases of all CD34(pos) cell sources were similar: CB 3942 ± 1554, adult peripheral mobilized blood 4702 ± 1826, and bone marrow (BM) 4143 ± 1908. The proportion of CD235a expression indicating erythroblast presence on Day 21 was slightly higher in the adult CD34(pos) cell sources: peripheral blood stem cells (96.7 ± 0.8%) and BM (98.9 ± 0.5%) compared to CB (87.7 ± 2.7%; p = 0.002). We were not able to induce further erythroid maturation in vitro.

CONCLUSION

This explorative study showed that fairly pure autologous erythroid-expanded cell populations could be obtained by a simple culture method, which should be optimized. Future challenges comprise obtaining ex vivo enucleation of RBCs with the use of a minimal manipulating approach, which can add up to autologous RBCs derived from CB in the treatment of anemia of prematurity.

Hb Treviso [α91(FG3)Leu→Phe (α2)]: a new slightly unstable hemoglobin variant with moderately decreased oxygen affinity

We report a new hemoglobin (Hb) variant, found in a North-East Italian family living in the city of Treviso. The proband, a non anemic 60-year-old male with a history of chronic rhinitis, allergy to Parietaria and suspected obstructive sleep apnea syndrome, was referred for blood gas analysis. Determination of the oxygen affinity revealed a p50 of 32.5 mmHg (control 27.5 mmHg) indicating a moderate decrease in oxygen affinity. An abnormal pattern compatible with an α Hb variant was observed on high performance liquid chromatography (HPLC); direct sequencing revealed a transition at codon 91 of the α2 gene (HBA2: c.274C>T) changing leucine into phenylalanine. Characterization and phenotype studies are reported.

Newborn screening for hemoglobinopathies using capillary electrophoresis

This chapter reports the essential elements needed to understand basic laboratory diagnostics consisting of separation and measurement of the hemoglobin fractions. Although well established, basic diagnostics require some background and some degree of experience for application and interpretation. Last generation methods, consisting of automatic systems like high performance liquid chromatography and capillary electrophoresis (CE), allow high through put analysis in adults and newborns. Newborn screening using CE is presented in some details, using as an example the Capillarysâ Neonat Hb system (Sebia, France), as an upcoming alternative, explaining the method, the interpretation of the results, the objectives, the follow up, the advantages, and the pitfalls.

Basic haemoglobinopathy diagnostics in Dutch laboratories; providing an informative test result

INTRODUCTION

After a first survey in 2001, the Dutch Association of Hematological Laboratory Research (VHL) advised its members to adopt a basic protocol for haemoglobinopathy carrier detection and to provide genetic information with all positive results to allow health-care professionals to inform carriers about potential genetic risks. This article reports on the compliance with these recommendations and their consequences.

METHODS

Clinical chemists of all 106 Dutch laboratories were invited to answer a survey on patient population, diagnostic techniques used, (self-reported) knowledge, use and effect of the additional information.

RESULTS

The average increase in diagnostic output was over 60% and the recommended basic protocol was applied by 65% of the laboratories. Over 84% of the laboratories reported to be aware of the additional recommendations and 77% to be using them. Most laboratories with limited diagnostic requests were still sending their cases to other laboratories and included the genetic information received from these laboratories in their diagnostic reports. The effect of information on subsequent 'family analysis' was estimated to be between 26 and 50%.

CONCLUSIONS

The present study shows an increase in diagnostic potential for haemoglobinopathy over the last decade, especially in the larger cities. Low 'family testing' rates were mostly found in areas with lower carrier prevalence or associated with local reluctance to pass the information to carriers. In spite of a dramatic improvement, too many carriers are still not informed because of lack of awareness among health-care providers and more education is needed.

Strategies for basic laboratory diagnostics of the hemoglobinopathies in multi-ethnic societies: interpretation of results and pitfalls

The consistent multi-ethnic migrations of the last decades have considerably changed the epidemiology of the hemoglobinopathies. Healthy carriers of these conditions are present today in many nonendemic parts of the world, and severely affected children are now born where these diseases were previously rare or unknown. Improving the competence in carrier diagnostics at the laboratory level is one of the first concerns when introducing management and primary prevention of the severe conditions in nonendemic areas. This review describes how and when carriers should be correctly diagnosed and informed. The essential technologies needed for basic carrier diagnostics in different situations are summarized in some detail, and interpretation of the results and a number of related problems are discussed. The role of the hematology laboratory is essential, particularly in nonendemic areas where the first line of health care is often insufficiently aware of hemoglobinopathy management. Carriers living in nonendemic areas can be appropriately diagnosed and informed regarding genetic risk and prevention by well-organized laboratories. Both basic and specialized diagnostics are needed for the correct treatment for the anemic carriers, for primary prevention in couples at risk and for state-of-the art care of severely affected patients.

Mosaic segmental uniparental isodisomy and progressive clonal selection: a common mechanism of late onset β-thalassemia major

Genomic DNA of 3 patients, born as healthy carriers and developing a late-onset severe transfusion-dependent beta-thalassemia major was studied by high-density genome wide SNP array analysis. A mosaic loss of heterozygosity for almost the entire 11p was found, not attributable to deletions but involving mosaicism for segmental paternal isodisomy of 11p. Mitotic recombination leading to mosaic segmental uniparental isodisomy on chromosome 11p in multiple tissues has been described as a molecular disease mechanism for a subset of sporadic Beckwith-Wiedemann syndrome cases. A similar mechanism also seems to be involved in causing late-onset disease in carriers of recessive mutations in other genes located in 11p, such as late-onset beta-thalassemia major and sickle cell disease. We suggest that the loss of maternally imprinted IGF-2 and H19 genes may account for the selective advantage of hematopoietic cells containing this segmental paternal isodisomy of 11p carrying the β-thalassemia mutation.

Non-invasive prenatal diagnosis of beta-thalassemia and sickle-cell disease using pyrophosphorolysis-activated polymerization and melting curve analysis

OBJECTIVE

The aim of this study was to develop a pyrophosphorolysis-activated polymerization (PAP) assay for non-invasive prenatal diagnosis (NIPD) of β-thalassemia major and sickle-cell disease (SCD). PAP is able to detect mutations in free fetal DNA in a highly contaminating environment of maternal plasma DNA.

METHODS

Pyrophosphorolysis-activated polymerization primers were designed for 12 informative SNPs, genotyped by melting curve analysis (MCA) in both parents. The PAP assay was tested in a series of 13 plasma DNA samples collected from pregnant women. A retrospective NIPD was performed in a couple at risk for SCD.

RESULTS

All PAP reactions were optimized and able to detect <3% target gDNA in a background of >97% wildtype gDNA. In all 13 cases, the paternal allele was detected by PAP in maternal plasma at 10 to 18 weeks of gestation. For the couple at risk, PAP showed presence of the normal paternal SNP allele in maternal plasma, which was confirmed by results of the chorionic villus sampling analysis.

CONCLUSIONS

In contrast to other methods used for NIPD, the combined PAP and MCA analysis detecting the normal paternal allele is also applicable for couples at risk carrying the same mutation, provided that a previously born child is available for testing to determine the linkage to the paternal SNPs.

Hb Haaglanden: a new nonsickling β7Glu>Val variant. Consequences for basic diagnostics, screening, and risk assessment when dealing with HbS-like variants

INTRODUCTION

To report a new hemoglobin variant undistinguishable from the common HbS on HPLC. To show the efficiency of the simplest confirmation method for HbS and to discuss the implications that may occur if HbS-like variants are wrongly reported as HbS.

METHODS

Basic hematology, separation and measurement of the Hb fractions, 'sickle test,' and molecular analysis.

RESULTS

The abnormal Hb fractions were eluting in the HbS window on HPLC, sickle test was however negative, and DNA sequencing of the beta globin gene revealed an unclassified variant HBBc.23A>T, p.Glu8Val in heterozygous form.

CONCLUSIONS

Although the amino acid substitution of this new variant is identical to that of HbS and shifted of a single amino acid position, no polymerization occurs in vitro. The sickle test is a valid method to confirm or exclude HbS trait in individual cases. Whenever the case is part of a possible couple at risk, then one has to use full DNA analysis in both partners not to miss hidden concomitant defects important for genetic risk predictions.

Towards a prevention program for β-thalassemia. The molecular spectrum in East Java, Indonesia

Defining the spectrum of specific thalassemia mutations is an important issue when planning prevention programs in large multi ethnic countries as is Indonesia. In a first attempt to define the prevalence of the common mutations in East Java we selected a cohort of 17 transfusion-dependent patients attending the Dr. Soetomo Hospital, Surabaya, Indonesia. After basic diagnostics we performed direct DNA sequencing for all β-globin genes. The results obtained on 34 independent chromosomes revealed the following prevalence rates: c.79 G>A p. Glu27Lys (Hb E) 47.0%; c.92+5G>C (IVS-I-5 G>C) 20.6%; c.109_110 delC p.Pro37Leu fs X7 [codon 35 (-C)] 17.6%; c.46del T p.Trp16Gly fsX4 [codon 15 (-T)] 5.9%; c.126_129delCTTT p. Phe42Leu fs X19 (codons 41/42) 2.9%; c.316-197 C>T [IVS-II-654 (C>T)] 2.9%; c*112 A>G (PolyA) 2.9%. Our preliminary results show that the distribution of the prevalent mutations in our cohort is quite homogeneous but with different forms than previously reported. This indicates that more studies on a larger scale and in different geographical areas are needed to refine our provisional results and to characterize the molecular background of the disease in the whole country.

Relationship between neonatal screening results by HPLC and the number of α-thalassaemia gene mutations; consequences for the cut-off value

Objectives

To evaluate the relationship between FAST peak percentage by adapted Bio-Rad Vnbs analysis using the valley-to-valley integration and genotypes with the aim to improve differentiation between severe α-thalassaemia forms (HbH disease) and the milder disease types.

Method

DNA analysis for α-thalassaemia was performed on 91 dried blood spot samples presenting normal and elevated FAST peak levels, selected during three years of Dutch national newborn screening.

Results

Significant differences were found between samples with and without α-thalassaemia mutations, regardless of the genetic profiles. No significant difference was demonstrated between HPLC in -α/αα and -α/-α, between -α/-α and –/αα and between –/αα and –/-α genotypes.

Conclusion

This study confirms that the percentage HbBart's, as depicted by the FAST peak, is only a relative indication for the number of α genes affected in α-thalassaemia. Based on the data obtained using the modified Bio-Rad Vnbs software, we adopted a cut-off value of 22.5% to discriminate between possible severe α-thalassaemia or HbH disease and other α-thalassaemia phenotypes. Retrospectively, if this cut-off value was utilized during this initial three-year period of neonatal screening, the positive predictive value would have been 0.030 instead of 0.014.

Occurrence of common and rare δ-globin gene defects in two multiethnic populations: thirteen new mutations and the significance of δ-globin gene defects in β-thalassemia diagnostics

INTRODUCTION

The aim of this review is to study the frequency of common and the occurrence of rare and novel mutations of the delta-globin gene and of Hb Lepore defects that might interfere with thalassemia diagnostics and to report the rationale of HbA2 estimation in the presence of delta- or alpha-gene mutations.

METHODS

A total of 135 cases suspected to have a delta-globin gene defect collected in a diagnostic center in the USA and in a reference laboratory in the Netherlands were characterized by molecular analysis.

RESULTS

Hb B2 was found at a frequency of at least 0.5% in the USA and 0.87% in the Netherlands. Known variants such as Hb A2-Babinga, Hb A2-Sphakia, Hb A2-Fitzroy, Hb A2-Flatbush, Hb A2-NYU, Hb A2-Grovetown, HbA2-Yialousa, Hb A2-Indonesia and several delta-thalassemia mutations were found together with 13 new mutations and two new polymorphisms, while Hb Lepores were regularly observed.

CONCLUSION

HbA2 mutations either structurally stable and visible or undetectable because of a thalassemia effect or instability are clinically asymptomatic but may compromise the diagnosis of beta-thalassemia minor. Stable mutations result in two HbA2 fractions of about half of the expected value. Expression defects are undetectable as a protein fraction but reduce the amount of HbA2 by half.

Fine-tiling array CGH to improve diagnostics for α- and β-thalassemia rearrangements

Implementation of multiplex ligation-dependent probe amplification (MLPA) for thalassemia causing deletions has lead to the detection of new rearrangements. Knowledge of the exact breakpoint sequences should give more insight into the molecular mechanisms underlying these rearrangements, and would facilitate the design of gap-PCRs. We have designed a custom fine-tiling array with oligonucleotides covering the complete globin gene clusters. We hybridized 27 DNA samples containing newly identified deletions and nine positive controls. We designed specific primers to amplify relatively short fragments containing the breakpoint sequence and analyzed these by direct sequencing. Results from nine positive controls showed that array comparative genomic hybridization (aCGH) is suitable to detect small and large rearrangements. We were able to locate all breakpoints to a region of approximately 2 kb. We designed breakpoint primers for 22 cases and amplification was successful in 19 cases. For 12 of these, the exact locations of the breakpoints were determined. Seven of these deletions have not been reported before. aCGH is a valuable tool for high-resolution breakpoint characterization. The combination of MLPA and aCGH has lead to relatively cheap and easy to perform PCR assays, which might be of use for laboratories as an alternative for MLPA in populations where only a limited number of specific deletions occur with high frequency.

Feasibility of nonselective testing for hemoglobinopathies in early pregnancy in The Netherlands

OBJECTIVE

To examine the feasibility of standardized hemoglobinopathy (HBP) carrier testing for pregnant women in The Netherlands in addition to the standard anemia screening.

METHODS

We assessed the prevalence of HBP in women at the time of the first pregnancy visit using both a prospective cohort (N = 703) and a retrospective series of women selected at random (N = 588). For the purpose of analysis, the population was divided into a high risk and a low risk group for HBP based on maternal ethnicity. Screening for HBP utilized standard screening tests for anemia, with additional high performance liquid chromatography (Variant II); molecular analysis was performed by Gap-polymerase chain reaction (Gap-PCR) and if necessary, direct sequencing and multiplex ligation-dependent probe amplification (MLPA). Family history was reported or collected from the medical records.

RESULTS

β-Globin defects were found in 3.9% of the total population (50/1291). The frequency in the high risk population was 5.6% (37/656), compared with 1.2% (6/501) in the low risk group. In the prospective study we found 30 HBP carriers, leading to testing of 16 partners and identification of two couples at risk. One affected child was born. Mean gestational age at the screening was 11.3 weeks with a standard deviation (SD) of 5.8.

CONCLUSION

We found that the prevalence of HBP carriers is high enough in our population to warrant HBP testing for the entire multiethnic population in early pregnancy at the time of anemia screening. This is feasible as most women had their booking early in their first trimester.

Iron depletion: an ameliorating factor for sickle cell disease?

We report some observations from our laboratory practice that might be important for the treatment of sickle cell disease (SCD). We describe data from two cases indicating that iron depletion might have a beneficial effect diminishing the formation of HbS in favor of HbF, possibly reducing the severity of the disease. We believe that it would be worthwhile to monitor the course of the disease comparing cases with identical genotypes with and without iron depletion, and we advise to consider chelation therapy to reduce iron overload in patients with SCD.

Hb Boskoop [HBA2c.112C>T p.Pro38Ser]: a new α2 chain variant observed in a Morrocan family

We describe a new nondeletional α-thalassemia (α-thal) determinant found in a Moroccan infant and in two members of his family. The new mutation generates an abnormal hemoglobin (Hb) as a consequence of a Pro→Ser amino acid substitution at codon 37 (old nomenclature) of the α2 gene. The new Hb variant is barely separable on high performance liquid chromatography (HPLC) but the expression of the α chain mutant measured on reversed phase chromatography is one-third of that expected from a stable α2 variant, which explains the mild α-thal phenotype observed in the carriers. As shown for other mutations described in our laboratory (i.e., Hb Gouda), this variant could also be common in the North African population, overlooked because of the mild phenotype and silent behavior on HPLC. Nevertheless, these silent variants could generate intermediate Hb H diseases in association with Mediterranean α(0)-thal deletion defect.

Implementing neonatal screening for haemoglobinopathies in the Netherlands

BACKGROUND

The birth prevalence of severe haemoglobinopathies such as sickle cell disease (SCD) in the Netherlands has been estimated to be at least 50 newborns per year. Neonatal screening for SCD was added to the Dutch screening programme in January 2007. We here evaluated three high performance liquid chromatography (HPLC) systems for application in neonatal screening for haemoglobinopathies, and present the results of a subsequent pilot screening programme.

METHODS

The Variant NewBorn Screening (Vnbs) HPLC system (Bio-Rad) was validated by analysing 131 blood samples and blood mixtures. Subsequently, the performance of the G7 (Tosoh BioScience) and Ultra (Primus Corporation) was compared with the Vnbs. The three HPLC analysers were tested in a pilot screening programme on 21,969 dried blood spot samples from the routine Dutch neonatal screening programme.

RESULTS

The pilot screening resulted in 188 abnormal patterns. The three HPLC devices presented comparable within- and between-run precision and detected the abnormal samples similarly. The high throughput, sampling systems, presentation of results, and integration of the chromatograms, however, were different.

CONCLUSION

All three analysers detected the same abnormal haemoglobins satisfactorily, but integrated the chromatograms with variable imprecision. Comparison of the results suggested that the Bio-Rad Vnbs was the preferred system. However, software adjustments were required to improve the diagnostic potential of this device for screening for beta- and alpha-thalassaemia.

Codon 24 (TAT>TAG) and codon 32 (ATG>AGG) (Hb Rotterdam): two novel alpha2 gene mutations associated with mild alpha-thalassemia found in the same family after newborn screening

We report two novel alpha2-globin gene mutations found in the same Surinamese family. The proband, a newborn presenting during neonatal screening with 21.3% Hb Bart's (gamma4), proved to be a carrier of the common -alpha(3.7) deletion and a novel codon 32 (ATG>AGG) transversion that we named Hb Rotterdam. The father carried the same point mutation with borderline hemoglobin (Hb), MCV and low MCH values. The mother presented with a significant microcytic hypochromic anemia and also carried the -alpha(3.7) deletion and a second novel TAT>TAG transversion generating a stop codon at position 24. Shortly thereafter, Hb Rotterdam was again found in two unrelated adult females and in a Canadian newborn, all of African origin, suggesting that Hb Rotterdam could be a frequently occurring alpha(T) determinant in the Black population. Screening and characterization of the mutations, phenotype/genotype correlation and the issue of reporting newborn carriers of alpha-thalassemia (alpha-thal) are discussed.

One-third of the new paediatric patients with sickle cell disease in The Netherlands are immigrants and do not benefit from neonatal screening

OBJECTIVES

To estimate the prevalence of children with sickle cell disease (SCD) in The Netherlands. To estimate the annual number of children newly diagnosed as having SCD and the proportion with diagnoses through neonatal screening To estimate the proportion of children with SCD receiving paediatric care in a comprehensive care setting.

DESIGN

Data from two sources, a survey of paediatric practices (n=107) and a laboratory database (n=20), were analysed by the capture-recapture method.

PARTICIPANTS

Children with SCD aged <18 years, either born before 2003 or newly diagnosed as having SCD between 2003 and 2007.

MAIN OUTCOME MEASURES

Prevalence, annual number of children newly diagnosed as having SCD, proportion of children with diagnoses through neonatal screening, proportion of children receiving paediatric care.

RESULTS

The prevalence of SCD in children living in The Netherlands on 1 January 2003 was 1:5152 (95% CI 1:4513 to 1:6015). In the next 4 years, the annual incidence was 1:2011 (95% CI 1:1743 to 1:2376). Nearly one-third (27%) of the children newly diagnosed as having SCD immigrated to The Netherlands after birth and would, therefore, be missed by the neonatal screening programme. Approximately 60% of all children with SCD were not reported by paediatricians.

CONCLUSION

The number of children with SCD in The Netherlands is much higher than previously estimated, and the majority of these children seem not to be reviewed regularly by a paediatrician. Children born abroad (27% of new cases) do not benefit from neonatal screening and are at high risk of life-threatening complications before SCD is diagnosed. As this introduces disparities in healthcare, the initiation of adequate measures should be considered.

Hb St. Truiden [α68(E17)Asn→His] and Hb Westeinde [α125(H8)Leu→Gln]: two new abnormalities of the α2-globin gene

We report two new abnormal hemoglobins (Hbs) caused by mutations on the α2 gene. One resulted into an Asn→His substitution at position 68, the other in a Leu→Gln substitution at position 125. The first mutation was observed in a 61-year-old North European Belgian male during Hb A(1c) analysis and subsequently in other members of his family. The variant was expressed at a normal level and caused no hematological abnormalities in the carriers. The second was found in a 27-year-old Turkish male living in The Hague, The Netherlands, who presented with microcytic hypochromic parameters without iron deficiency and was also carrier of the common α2 IVS-I (-5 nt) deletion.

Newborn screening for hemoglobinopathies using capillary electrophoresis technology: Testing the Capillarys Neonat Fast Hb device

OBJECTIVES

To diagnose hemoglobinopathies in newborns by separating and measuring the Hb fractions on high throughput capillary electrophoresis. To test and validate the Capillarys Neonat Fast Hb device (Sebia) on fresh and dry blood samples.

DESIGN AND METHODS

The Hb fractions in 1.600 cord blood samples from the multi ethnic Dutch population were separated and measured. Further, the sensitivity, specificity and reproducibility of the device in detecting abnormalities and measuring the Hb fractions were estimated.

RESULTS

The apparatus separated all significant Hb fractions that should be detected during newborn screening (NBS) with 100% sensitivity. The reproducibility of the migrations guaranteed putative specificity for the few relevant frequent variants observed (HbS, C, and E). The estimation of the HbA and F fractions proved reliable using a well-designed integration mode.

DISCUSSION

Due to the limited number of samples no cases with sickle cell disease or β-thalassemia major were found in this cohort. However, the heterozygous state for the common variants associated with these diseases was clearly recognizable. The measurements were sufficiently precise to recognize sickle cell disease, β-thalassemia major and intermedia and to identify carriers including possible β-thalassemia. Therefore, Capillarys Neonat Fast Hb (Sebia) can be considered as a valid instrument for NBS of the Hemoglobinopathies on fresh and dry blood samples.

Phenotypic expression and origin of the rare beta-thalassemia splice site mutation HBB:c.315 + 1G>T

We present the hematological characteristics of five patients from Surinam and the bordering French Guyana, who are carriers of the rare beta-thalassemia (beta-thal) mutation HBB:c.315+1G>T. Analysis of the phenotype/genotype relationship shows that this allele is a beta(0)-thal variant and illustrates the modulating effect of the alpha-globin gene status on the beta-thal phenotype. The ethnic origin of the five probands, belonging to the so-called Bush Negroes Maroons of Surinam and French Guyana, strongly suggests that this beta-thal mutation has a West African origin and spread in this ethnic group because of a founder effect and/or genetic drift.

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.