Sickle cell anemia and α-thalassemia: a modulating factor in homozygous HbS/S patients in Oman.

We report the general phenotype severity and the hematological presentation in a cohort of 125 sickle cell anemia (SCA) patients with identical homozygous HbS/S genotype and categorized by identical ß(S) haplotype, both with and without alpha thalassemia. No clear general phenotype correlation was found when patients were compared regardless of the haplotype but overall, patients with homozygous alpha thalassemia (α-/α-) had the highest Hb, HCT, RBC and the lowest MCV, MCH and MCHC levels. When patients with identical haplotype were compared, the mildest hematological and clinical conditions were observed in patients of the Asian/Asian haplotype, also known as Arab-Indian haplotype, and carriers of α-thalassemia, suggesting an additional ameliorating effect of alpha thalassemia. In conclusion, our results show that alpha thalassemia improves the hematological conditions but amelioration of the general disease severity is only noticed when compared in cohorts of the same haplotype.

Molecular diagnostics of the HBB gene in an Omani cohort using bench-top DNA Ion Torrent PGM technology.

Hemoglobinopathies, such as sickle cell disease (SCD) and beta-thalassemia major (TM), are severe diseases and the most common autosomal recessive condition worldwide and in particular in Oman. Early screening and diagnosis of carriers are the key for primary prevention. Once a country-wide population screening program is mandated by law, a sequencing technology that can rapidly confirm or identify disease-causing mutations for a large number of patients in a short period of time will be necessary. While Sanger sequencing is the standard protocol for molecular diagnosis, next generation sequencing starts to become available to reference laboratories. Using the Ion Torrent PGM sequencer, we have analyzed a cohort of 297 unrelated Omani cases and reliably identified mutations in the beta-globin (HBB) gene. Our model study has shown that Ion Torrent PGM can rapidly sequence such a small gene in a large number of samples using a barcoded uni-directional or bi-directional sequence methodology, reducing cost, workload and providing accurate diagnosis. Based on our results we believe that the Ion Torrent PGM sequencing platform, able to analyze hundreds of patients simultaneously for a single disease gene can be a valid molecular screening alternative to ABI sequencing in the diagnosis of hemoglobinopathies and other genetic disorders in the near future.

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, ß-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.

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.

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.

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.

Hb Haaglanden: a new nonsickling ß7Glu>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.

ICSH recommendations for the measurement of haemoglobin F.

Measurement of the Haemoglobin F in red cell haemolysates is important in the diagnosis of 뫧 thalassaemia, hereditary persistence of fetal haemoglobin (HPFH) and in the diagnosis and management of sickle cell disease. The distribution of Hb F in red cells is useful in the diagnosis of HPFH and in the assessment of feto-maternal haemorrhage. The methods of quantifying Hb F are described together with pitfalls in undertaking these laboratory tests with particular emphasis on automated high-performance liquid chromatography and capillary electrophoresis.

ICSH recommendations for the measurement of haemoglobin A2.

Although DNA analysis is needed for characterization of the mutations that cause ß-thalassaemia, measurement of the Hb A(2) is essential for the routine identification of people who are carriers of ß-thalassaemia. The methods of quantitating Hb A(2) are described together with pitfalls in undertaking these laboratory tests with particular emphasis on automated high-performance liquid chromatography and capillary electrophoresis.

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.

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.

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 ß-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.

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 ß-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, ß-thalassemia major and intermedia and to identify carriers including possible ß-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.

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.

Prevention strategies for severe hemoglobinopathies in endemic and nonendemic immigration countries: the Latium example.

OBJECTIVE: To review prevention data for hemoglobinopathies from Latium, a large Italian region with a considerable immigrant population and with a well-established regional prevention program. METHOD: All data pertaining to population screening for hemoglobinopathies in the Latium region were reviewed for the period 1994-2007. Screening was performed universally in secondary schools and to pregnant couples at the time of prenatal care. We have examined the trends in positive screening results as well as the type of hemoglobinopathies detected during the study period, and we have correlated them to the type of population (immigrant vs indigenous). RESULTS: From 1994 to 2007, 167 235 individuals were examined for carrier status for hemoglobinopathies, and 10 353 of them (6.2%) were immigrants. We have registered a threefold increase in rates of screen-positive subjects who belonged to ethnic minorities during the study period (from 2.7% in 1994 to 9.8% in 2007). Over half of the screen-positive subjects (5397/10 353) presented no hematological anomalies, 24% (n = 2472) had iron deficiency, and 24% (n = 2484) was classified as putative carriers. Among the last group, 22.6% were carriers of beta-thalassemia, 48% were suspected alpha-thalassemia carriers, and the remainder had less common hemoglobinopathies. While the prevention program resulted in nearly zero births of autochthonous newborns affected by severe hemoglobinopathies, a rise in number of affected individuals was noted among immigrants. Screening of secondary school students was accepted by 67% of immigrant parents, resulting in 9737 pupils screened between 2002 and 2006. CONCLUSION: Existing preventive programs for severe hemoglobinopathies should adapt to changes in population ethnicities. Screening for hemoglobinopathies at school age is an efficient strategy.

Evaluating five dedicated automatic devices for haemoglobinopathy diagnostics in multi-ethnic populations.

We have tested five haemoglobin (Hb) separation apparatuses, dedicated to haemoglobinopathy diagnostics. These are the four high performance liquid chromatography devices: VARIANT II, HA 8160, G7, Ultra(2) and the Capillary Electrophoresis apparatus from Sebia. In the first place, we focussed on the capacity of all apparatuses to detect the most common structural variants relevant for public health, these being HbS, HbC, HbE, HbD-Punjab and HbO-Arab. We then compared how the high HbA(2)beta-thalassaemia carriers were identified. All apparatuses were able to identify carriers of these traits with the expected sensitivity and specificity. With the primary goal of a high degree of conformity in basic diagnostics of haemoglobinopathies, we present the interpretation and the significance of the results on all apparatuses, and we comment on the unavoidable problems and solutions.

The role of haemoglobin A(2) testing in the diagnosis of thalassaemias and related haemoglobinopathies.

The increase in haemoglobin (Hb)A(2) level is the most significant parameter in the identification of beta thalassaemia carriers. However, in some cases the level of HbA(2) is not typically elevated and some difficulties may arise in making the diagnosis. For these reasons the quantification of HbA(2) has to be performed with great accuracy and the results must be interpreted together with other haematological and biochemical evidence. The present document includes comments on the need for accuracy and standardisation, and on the interpretation of the HbA(2) value, reviewing the most crucial aspects related to this test. A practical flow-chart is presented to summarise the significance of HbA(2) estimation in different thalassaemia syndromes and related haemoglobinopathies.

Starting neonatal screening for haemoglobinopathies in The Netherlands.

Neonatal screening for haemoglobinopathies started in The Netherlands on 1 January 2007. The method of choice, high-performance liquid chromatography, and the universal setting have shown that the predicted incidence is indeed present in the country. Patients and carriers are reported in order to prevent morbidity, and for the primary prevention of serious haemoglobinopathies. Background, preceding discussion, health gain, implementation, provisional results and ethics issues are discussed, as well as matters concerning technology, know-how, and ongoing and future developments.

Segmental duplications involving the alpha-globin gene cluster are causing beta-thalassemia intermedia phenotypes in beta-thalassemia heterozygous patients.

We describe two cases of simple heterozygosity for the common beta degrees -thalassemia mutation beta 39 (C-->T), both presenting with a thalassemia intermedia phenotype. In both cases synergic effect deriving from membrane defects or red cell enzyme deficiencies were excluded. In one case a triplication of the alpha-globin genes was found which did not justify the severity of the transfusion-dependent phenotype. Multiplex ligation-dependent probe amplification (MLPA) analysis of the alpha-globin gene cluster revealed two new rearrangements, consisting of a full duplication of the alpha-globin genes locus including the upstream regulatory element. In one case the duplication was in the presence of the common anti-alpha(3.7) triplication in trans, resulting in a total of 7 active alpha-globin genes. In the other case the duplicated allele and the normal allele in trans resulted into a total of 6 active alpha-globin genes. We report the clinical and hematological data and the molecular analysis and discuss the occurrence of alpha-globin genes duplication defects in cases of beta-thalassemia heterozygotes with thalassemia intermedia phenotypes.