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.

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.

Hb Lansing (HBA2: c.264C > G) and a new ß 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 ß-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 ß(+)-thalassemia (ß(+)-thal) mutation.

Broader spectrum of ß-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 ß-thalassemia (ß-thal) mutations in Oman by examining cases from seven different regions and comparing the prevalence with neighboring countries. A total of 446 cases of ß hemoglobinopathies was obtained and analyzed to determine the frequency and distribution of the different ß alleles. The molecular spectrum of ß-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 ß-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.

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 ß-globin gene defects, emphasize the necessity of adding α-thal testing to pre marital programs for accurate genetic counseling.

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

We report a new silent ß-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 ß-thalassemia (ß-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 ß-globin gene, leading to an Ala → Thr single amino acid substitution that was inherited from the healthy father.

[Haemoglobinopathy in the 21st century: incidence, diagnosis and heel prick screening]. / Hemoglobinopathie in de 21e eeuw: incidentie, diagnose en hielprikscreening.

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.

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 ß-thalassemia (ß-thal) such as Oman. This is because coinherited δ-globin gene defects can interfere with the basic diagnosis of a ß-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 ß-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.

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.

Mosaic segmental uniparental isodisomy and progressive clonal selection: a common mechanism of late onset ß-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 ß-thalassemia mutation.

A single-tube multiplex gap-polymerase chain reaction for the detection of eight ß-globin gene cluster deletions common in Southeast Asia.

Up to now, more than 200 different ß-thalassemia (ß-thal) mutations have been characterized. The majority are point mutations causing expression defects. Only approximately 10.0% of the defects are caused by large deletions involving the ß-globin gene cluster causing ß(0)-thal, (δß)(0)-thal, (G)γ((A)γδß)(0)-thal and other conditions with or without persistence of fetal hemoglobin (Hb). For the prevention of severe forms of ß-thal intermedia and ß-thal major, it is important to identify carriers of point mutations as well as carriers of deletions. ß-Thalassemia and related disorders are most commonly present among populations from all Mediterranean countries as well as Southeast Asia, India, Africa, Central America and the Middle East. Twelve relatively frequently occurring deletion types have been described involving the ß-globin gene cluster. These include the 105 bp ß(0)-thal deletion, the 619 bp deletion, the 3.5 kb deletion, the Southeast Asian (SEA) deletion, the Filipino deletion, Hb Lepore, the Thai (δß)(0)-thal, the Siriraj J (G)γ((A)γδß)(0)-thal, the Chinese (G)γ((A)γδß)(0)-thal, the Asian Indian deletion-inversion (G)γ((A)γδß)(0)-thal as well as the (hereditary persistence of fetal hemoglobin) HPFH-6 and HPFH-7 deletions. To improve the rapid detection of the eight common ß-globin cluster deletions in Southeast Asian countries, a simple molecular technique based on a single-tube multiplex gap-polymerase chain reaction (PCR) has been developed in this study. This technique provides a fast, simple and cost effective diagnostic test for deletion types of ß-thal that can be applied in every molecular diagnostic laboratory having standard PCR equipment.

Providing appropriate genetic information to healthy carriers of hemoglobinopathy can be a welcome and safe initiative: the Latium example.

AIMS: To register the opinions and feelings of (presumed) unaware healthy hemoglobinopathy carriers, receiving information on their carrier status. METHODS: We collected 259 interviews from the parents of secondary school students, after their children had been provisionally diagnosed as hemoglobinopathy carriers during the routine school screening campaign imbedded in the public health care program of the Latium region (Central Italy). After screening of the children, all parents received a standard reassuring letter informing them about the presumed healthy carrier status of their children and were invited for a confirmation of the trait and for an additional explanation if needed. RESULTS: We have analyzed 219 interviews (84.5%) from indigenous subjects and 40 from allochthonous people (15.5%) being either recent immigrants or mixed couples. The average age of the parents was 45.5 years. Only 51 (19.7%) had previous knowledge of their carrier status, while the rest were unaware. When reading the letter with the provisional diagnostic result of their child, emotions that could be considered undesirable were present in about 60% of the cases. Nevertheless, the information was experienced as welcome, clear, and useful by 100% of the participants. When asked about the option of prenatal diagnosis (PD) in case of genetic risk, 85.7% and 87.5% of the autochthonous and allochthonous interviewed declared either to be in favor or to eventually consider PD, while only 14.3% and 12.5% would not consider it for various reasons. DISCUSSION: During our study, we registered undesirable feelings as well as welcome reactions: the first being experienced during the very first reading of the letter and the second after reflection on and understanding of the content during the visit to the center later on. Significantly, satisfaction and understanding of the advantage of knowledge was registered in 100% of the cases during our enquiry.

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 ß-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.

A novel α(0) -thalassemia deletion in a Greek patient with HbH disease and ß-thalassemia trait.

OBJECTIVES: To determine the molecular basis in a Greek child suspected of having HbH disease and ß-thalassemia trait. METHODS: Standard hematology, Hb electrophoresis, and HPLC. Multiplex ligation-dependent probe amplification (MLPA), direct sequencing, and breakpoint characterization by NimbleGen fine-tiling array analysis. RESULTS: The index patient showed a moderate microcytic hypochromic anemia with normal ZPP and elevated HbA(2) , indicative for ß-thalassemia trait. However, the moderate microcytic hypochromic anemia along with the observation of HbH inclusions in occasional red blood cells suggested a coexisting α-thalassemia. Molecular analysis indicated that the propositus inherited the ß(+) -thalassemia mutation IVS2-745 (c>g) and a novel α(0) -thalassemia deletion from the mother, and the common non-deletion α-thalassemia allele α(2) (-5nt)α from the father. The α(0) -thalassemia deletion, named - -(BGS) , is approximately 131.6 kb in length. It removes the major regulatory elements along with the functional α-globin genes but leaves the theta-gene intact. CONCLUSIONS: The compound interaction of a ß-thalassemia defect along with a single functional α-globin gene is quite rare. Although patients with HbH/ß-thal and simple HbH disease have comparable levels of Hb, the absence of free ß-globin chains and thus detectable non-functional HbH means that in HbH/ß-thal, the levels of functional Hb are higher, resulting in a better compensated functional anemia. Rare large deletions as the one described here remain undetected by gap-PCR in routine molecular screening. The introduction of MLPA as a diagnostic screening tool may improve laboratory diagnostics for these defects. The use of NimbleGen fine-tiling arrays may give additional information about the precise location of breakpoints.

Fine-tiling array CGH to improve diagnostics for α- and ß-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.