We report an update of the α-globin gene point mutations resulting in structural modification associated with an α-thalassemia (α-thal) phenotype. These variants, barely symptomatic in the heterozygous state, are either unstable due to folding defects and/or defects in binding to α-hemoglobin stabilizing protein (AHSP). This is predicted to result in precipitation of the unstable α chains or Hb variant, a concomitant decrease in the overall quantity of normal α-globin in the red cells and a potential degree of anemia and possibly, hemolysis. Genotype/phenotype correlation and potential genetic risk in combination with common or less common α-thal defects are discussed.
Prevention of Hemoglobinopathies has developed around the world based upon the experience done in pioneering endemic countries and is now facing a new phase in nonendemic areas with a recent immigration history.We describe two situations, taking Latium (central Italy) and The Netherlands as two models for endemic and non-endemic countries both confronted with a large multi-ethnic immigrant society.We present prevention results and discuss aspects such as local knowledge and organization.We illustrate the importance of issues like information, carrier diagnostics, screening, counseling and prenatal diagnosis in particular situation of contrasting interest an different ethical opinions.We conclude by underlining the importance of implementing primary prevention at the European level, based upon better information, diagnostics and counseling.
We report a novel thalassemia determinant found in a Nigerian woman living in the Netherlands, resulting from a 2 bp insertion at codons 9/10 of the β-globin gene (HBBc.28_29insTA p.Ser10LeufsX11). The novel defect causes a frameshift with a consequent premature TGA stop codon, located at 11 positions downstream from the mutated codon. The phenotype was typical of a β-thalassemia (β-thal), trait with high RBC counts and compensated mild microcytic anemia. However, the Hb A2 level was reported to be normal due to the presence of the common Hb A2' or Hb B2 [δ16(A13)Gly→Arg, GGC>CGC] variant that was not taken into account. We also present the opposite but comparable situation found in an a Palestinian man living in the USA. He was a carrier of a common β-globin gene defect [codon 6 (–A), HBB:c.20delA] in combination with a novel δ-globin gene defect at codon 6 [HBD. c.19G>C, Glu6Gln] that we have named Hb A2-Ramallah. In both cases, the provisional diagnosis could have been compromised when based on the measurement of the normal Hb A2 fraction only.
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 β- and α-thalassaemia.
Background Obstructive sleep apnea (OSA) is linked to cardiovascular diseases (CVD). The obstructive apnea-hypopnea index (oAHI) used for diagnosing and grading OSA has limitations in predicting CVD. The present study assessed and compared the association between nocturnal hypoxemia parameters and left ventricular hypertrophy (LVH). Methods A cross-sectional study was conducted on 187 consecutive adult outpatients diagnosed with OSA after home cardiorespiratory polygraphy. Blood pressure (BP) control was tested with ambulatory blood pressure monitoring (ABPM). A standard transthoracic cardiac ultrasound examination assessed LVH. Oximetry parameters were grouped into a single parameter (Oxy-score) using factor analysis (the higher the Oxy-score, the better nocturnal oxygenation), which was tested for association with LVH. Results Mean age: 60±12 years. Male sex: 75%. Overweight/obese: 94%. The prevalence of arterial hypertension and LVH were 92% and 75%, respectively. The prevalence of severe OSA was 44%, with a mean oAHI of 32±19. Patients with LVH had significantly higher oAHI (34±19 versus 27±18, p=0.030), oxygen desaturation index (ODI) (41±23 versus 30±18, p=0.004), and worse oximetry parameters. Oxy-score results were independently associated with LVH (adj. OR=0.45, p=0.044). oAHI lost its independent relationship with LVH when the model included the Oxy-score. ROCs showed that oAHI was less accurate in predicting LVH than Oxy-score [AUC 0.63 (95% CI 0.59–0.68) versus AUC 0.70 (95% CI 0.65–0.74), respectively, p=0.005]. Conclusion Nocturnal oximetry parameters, grouped into a single parameter as a proxy of the global hypoxic burden, proved to be a better and independent predictor of LVH than oAHI, supporting the pivotal relevance of oximetry parameters in OSA patients beyond oAHI.
We describe a novel hemoglobin (Hb) variant, caused by a CCC > TCC transition at codon 77 on the α gene. The mutation was found in two unrelated patients, in one patient on the α1 gene and in the other patient on the α2 gene. Both are anemic patients of African origin. Due to the neutral Pro→Ser substitution, Hb Nile could not be separated from Hb A with common short-run screening methods for high performance liquid chromatography (HPLC) and capillary electrophoresis, but was evidently present after prolonged cation exchange HPLC or separation by isoelectric focusing (IEF). Reversed phase HPLC separation of the globin chains revealed the normal and abnormal α chains with an expression of about 20% for Hb Nile[A1], indicative of normal expression and stability of the mutant protein.
We report three new α-thalassemia (thal) point mutations detected during newborn screening for hemoglobinopathies. The first mutation is a single nucleotide deletion (−A) that abolishes the translation initiation codon of the α2-globin gene, detected in a newborn of Hmong ethnicity who carried the Southeast Asian α0-thal deletion (αTα/– –SEA). The second mutation, a frameshift caused by a single nucleotide deletion in exon 2 of the α1-globin gene [codon 78 (−C)], was detected in a Black/Chinese newborn who also carried the Southeast Asian α0-thal deletion (ααT/– –SEA). The third mutation was a frameshift in exon 3 of the α2-globin gene, codons 113/114 (−C). This mutation was detected in a newborn who carried the 3.7 kb α+-thal deletion (αTα/–α3.7).
Background Autologous cord blood ( CB ) red blood cells ( RBC s) 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 CD 34‐positive ( CD 34 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 CD 34 pos cells. However, the RBC s contaminating the buffy coat remained present during the culture with uncertain quality. Premature and full‐term CB CD 34 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 CD 34 pos cell sources were similar: CB 3942 ± 1554, adult peripheral mobilized blood 4702 ± 1826, and bone marrow ( BM ) 4143 ± 1908. The proportion of CD 235a expression indicating erythroblast presence on Day 21 was slightly higher in the adult CD 34 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 RBC s with the use of a minimal manipulating approach, which can add up to autologous RBC s derived from CB in the treatment of anemia of prematurity.
We conducted population specific confidential enquiries among immigrants who had never experienced hemoglobinopathies, to study the reliability of this approach in estimating the wish for primary prevention by prenatal diagnosis and selective abortion.We collected data from Surinamese Hindustanis (n = 119), Surinamese and Antillean Afro-Americans (n = 105) and North Africans (mainly Moroccans) (n = 102), living in Holland. We also interviewed 105 informed individuals of different ethnicities, all members of the multi-ethnic patients and carriers' organization 'OSCAR Nederland'.On average, 68% of the Surinamese Hindustanis and 42% of the Surinamese Afro-Americans were in favor of selective abortion in case of affected pregnancy. Remarkably, 77% of the last group wanted to be tested for carrier diagnostics and 67% declared to have knowledge of the disease before they were informed. Only 16% of the Moroccans were in favor of selective abortion in case of an affected fetus, while 79% wanted to have blood analysis to establish their carrier status.The apparently limited wish for selective abortion expressed by Moroccans is in contrast with the high number of illegal abortions reported among married women in Morocco (39%). The wish for selective abortion among informed members of the patients' organization was more than 80%.
