Detection of Complex Hemoglobinopathies: Recommendations on Screening and DNA Testing

The following recommendations should be taken into account during the evaluation and elucidation of the complex hemoglobinopathies: (a) in complex hemoglobinopathies performing DNA studies on all family members might be essential; (b) complex gene-gene interactions offer major diagnostic challenges both at the technical and clinical level; (c) hematological & DNA analyses must be run in parallel. Some cases may be straight forward but others may require indepth DNA work-up; (d) co-inheritance of α-thalassemia offers added challenge as it may affect phenotype significantly; (e) sickle cell anemia (SS), co-inherited with a-thal, can be a phenocopy of Sβ0-thal. The HbA2 increase can be mistaken for Sβ-thal. DNA Sequencing is imperative; (f) only a selected number of normal MCV, MCH, borderline HbA2 cases must be referred for DNA analysis. However, in certain cases, following hematological and family evaluation, the β and δ genes may need to be sequenced; (g) DNA Sequencing will increasingly become the method of choice for screening and DNA mutation analysis. However, new methods like MLPA-which analyzes gene dosage- must be used more commonly to rule out deletion mutants to avoid false negative sequencing results; (h) these recommendations should be reviewed every 2–3 years reflecting new methods, new findings and new findings from ethnic groups.诊断和说明复杂血红蛋白病时，建议考虑以下几点： (a）针对复杂的血红蛋白病，有必要对所有家庭成员开展DNA研究；(b) 复杂的基因-基因交互作用可能使诊断在技术和临床层面上颇受挑战；(c) 血液和DNA分析须同时进行。 有些病例简单，但另外一些病例可能需要开展深层次的DNA检查；(d) 由于α型地中海贫血可能严重影响表型，α型地中海贫血的共同继承特征更具挑战；(e) 共同继承α型地中海贫血的镰状细胞贫血（SS），可以作为Sβ0型地中海贫血的显型。 HbA2增量可能错误判断为Sβ0型地中海贫血。 必须进行DNA测序。(f) 为方便DNA分析，必须参考选定数量的MCV、MCH、边境线HbA2正常病例。 然而，在某些情况下，继血液和家庭成员诊断后，可能需要测定β和δ基因的顺序；(g) DNA测序将逐渐成为筛查和DNA突变分析的选择方法。 然而，为避免“假阴性”测序结果，必须更普遍地使用分析基因量的新方法（比如MLPA），以排除缺失突变体；(h)应每2–3年审查一次这些推荐方法，反映新方法，新发现以及来自少数族群的新发现。

[The significance of admission hs-CRP in patients undergoing primary percutaneous intervention for acute myocardial infarction]

OBJECTIVES

We evaluated the role of admission high-sensitivity C-reactive protein (hs-CRP) level in estimating myocardial perfusion and in-hospital adverse events in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI).

STUDY DESIGN

The study included 43 consecutive patients (34 males, 9 females; mean age 59+/-11 years) who underwent PCI for STEMI within six hours after the onset of symptoms. Coronary angiograms were evaluated with respect to TIMI flow grade, corrected TIMI frame count, and myocardial blush grade (MBG). Electrocardiograms obtained 90 min after PCI were analyzed for ST-segment resolution. In-hospital adverse events were recorded. hs-CRP level was measured by immunonephelometry in blood obtained immediately before PCI.

RESULTS

The mean hs-CRP level was 1.35+/-1.17 mg/dl. Based on the median hs-CRP value (0.98 mg/dl), 22 patients with a low hs-CRP level had a lower frequency of hypertension (p=0.047), decreased TIMI frame counts of the left anterior descending (p=0.010) and circumflex (p=0.033) arteries, a higher rate of ST resolution (p=0.000), improved MBG (p=0.015), and shorter hospitalization (p=0.028). Adverse events occurred in six patients (14%), in five of whom (5/21) the hs-CRP level was above 0.98 mg/dl. hs-CRP was significantly correlated with corrected TIMI frame counts of the left anterior descending (r=0.388, p=0.01) and circumflex arteries (r=0.336, p=0.027), length of hospitalization (r=0.357, p=0.019), and inversely correlated with MBG (r=-0.415, p=0.006). In multivariate regression analysis, hs-CRP was found to be an independent predictor of ST resolution (p=0.008). ROC analysis showed that a higher level of hs-CRP than 0.88 mg/dl predicted poor MBG with 73% sensitivity and 31% specificity (95% CI 0.577-0.899, p=0.01).

CONCLUSION

In STEMI patients undergoing primary PCI, high levels of admission hs-CRP are associated with poor myocardial perfusion and longer hospitalization.

[The effect of plasma asymmetric dimethylarginine (ADMA) level and L-arginine/ADMA ratio on the development of coronary collaterals]

OBJECTIVES

It has been shown that asymmetric dimethylarginine (ADMA), an endogenous competitive antagonist of nitric oxide (NO) synthase, inhibits angiogenesis by reducing the production and bioavailability of NO. We investigated the effect of plasma ADMA level and L-arginine/ADMA ratio on the development of coronary collateral arteries.

STUDY DESIGN

The study consisted of 94 patients (66 males, 28 females; mean age 59+/-11 years) who underwent coronary angiography for suspected coronary artery disease and were found to have severe stenosis (>95%) in at least one major coronary artery. The patients were evaluated in two groups with poor (Rentrop score 0-1, n=44) and good (score 2-3, n=50) coronary collateral circulation according to the Rentrop collateral scoring system. Plasma levels of ADMA and L-arginine were measured by high-performance liquid chromatography.

RESULTS

The two groups were similar with regard to basal characteristics and cardiovascular risk factors (p>0.05) except for stable angina, which was more common in patients with Rentrop score 2-3 collateral circulation (p<0.001). Despite similar L-arginine levels (p>0.05), patients with Rentrop score 0-1 had a significantly higher ADMA level (p=0.003) and lower L-arginine/ADMA ratio (p=0.019). Multivariate logistic regression analysis showed that plasma ADMA concentration was an independent predictor of coronary collateral development (odds ratio=0.674; 95% confidence interval=0.508-0.894; p=0.006).

CONCLUSION

Elevated plasma ADMA concentrations are associated with a poorly developed coronary collateral circulation, suggesting that dysregulation of the NO synthase pathway may result in impaired collateral development.

Asymmetric dimethylarginine plasma concentrations and L-arginine/asymmetric dimethylarginine ratio in patients with slow coronary flow

OBJECTIVE

Elevated levels of nitric oxide synthase inhibitor, asymmetric dimethylarginine (ADMA) is considered to be a marker of endothelial dysfunction and increased risk of cardiovascular disease. Recent reports have implicated endothelial dysfunction as an underlying pathophysiological mechanism of slow coronary flow (SCF) phenomenon. Accordingly, we investigated plasma L-arginine, ADMA concentrations and L-arginine/ADMA ratio in patients with SCF in comparison with participants having normal coronary flow.

METHODS

We measured plasma levels of L-arginine and ADMA by high-performance liquid chromatography in 31 participants with SCF and 31 age and sex matched control participants with normal coronary flow. Coronary flow was quantified using the thrombolysis in myocardial infarction (TIMI) frame count method.

RESULTS

The patients with SCF were detected to have significantly higher concentrations of plasma ADMA (P=0.006) and lower L-arginine/ADMA ratio compared with participants with normal coronary flow (P=0.002). In addition, both ADMA and L-arginine/ADMA ratio were significantly correlated with mean TIMI frame count and TIMI frame count for each coronary artery in patients with SCF and multivariate regression analysis identified plasma ADMA as an independent predictor for SCF. In the receiver operator characteristics curve analysis, patients with SCF were detected by plasma ADMA level with a sensitivity, specificity of 64.5%, 74.2%, at a cut-off of >2.4 micromol/l and L-arginine/ADMA ratio with a sensitivity, specificity of 77.4%, 67.7% at a cut-off of <36.6.

CONCLUSION

Our findings provide evidence to support the hypothesis that endothelial dysfunction may be an important factor in the pathogenesis of SCF.

Evaluation of left ventricular diastolic functions in patients with frequent premature ventricular contractions from right ventricular outflow tract

This study was sought to examine the effects of repetitive monomorphic premature ventricular contractions (PVCs) on left ventricular (LV) diastolic function. Thirty-three symptomatic patients (Study group, 10 males, mean age 40 +/- 8 years) with normal LV systolic function and repetitive PVCs originating from the right ventricular outflow tract (RVOT-PVCs) on 24-h Holter monitoring, and 30 healthy controls (Control group, 9 males, mean age 37 +/- 9 years) were enrolled in the study. None of the patients had structural heart disease. Diastolic function was assessed by echocardiographic mitral inflow pattern and tissue Doppler imaging. The study group displayed a lower E/A ratio, longer isovolumetric relaxation time (IVRT), and longer E-wave deceleration time (EDT). In the study group 13 patients showed impaired relaxation. While mean values of the systolic velocity (Sa), early diastolic velocity (Ea), and early/late diastolic velocity (Ea/Aa) ratio were significantly lower in the study group, the Aa velocity and E/Ea ratio were significantly higher. Ea velocity was <10 cm/s in 7 study patients. Mitral inflow pattern and Ea velocity was normal in all controls. Significant correlations were found between ventricular premature beats percentage and early to late transmitral flow velocity ratio, EDT, IVRT, Ea velocity, the Ea/Aa ratio, and the E/Ea ratio. In multivariate analysis, total PVC count and age were found to be independent predictors of impaired relaxation. These results suggest that repetitive monomorphic RVOT-PVCs lead to abnormalities of LV diastolic function that may contribute to clinical symptoms in patients with structurally normal hearts.

Left ventricular diverticulum with contractile function in an unusual site

The diverticulum of the left ventricular cavity is a rare congenital malformation. Various imaging modalities such as echocardiography, computed tomography, magnetic resonance imaging, and left ventriculography might be used for anatomic and functional properties of this abnormality. This report presents the case of a 48-year-old man with a contractile left ventricular diverticulum in the left ventricular outflow tract area and the evaluation with real-time multiplane and 3-dimensional transthoracic echocardiography.

Assessment of the ear and otoacoustic emission findings in fibromyalgia syndrome

OBJECTIVE

We aimed to assess otoacoustic emission (OAE) findings in fibromyalgia (FM) syndrome.

METHODS

Thirty-two ears of 16 female patients with FM syndrome and 30 ears of 15 healthy female controls were also included in the study. Pure tone audiometry, speech discrimination testing, tympanometry and otoacoustic emission testing (both transiently evoked and distortion product) were performed.

RESULTS

There was no significant difference between the pure tone hearing results of the patients and controls (p > 0.05). There was no significant difference between the distortion-product-otoacoustic emission results of the patients and controls. Audiologic findings of the patients with and without otologic symptoms were not significantly different than controls (p > 0.05).

CONCLUSION

Although FM patients generally have subjective symptoms related to ear, clinical or laboratory assessments usually fail to find out any objective finding related to these subjective symptoms. The otologic functions seem spared in FM syndrome.

Molecular Heterogeneity of Beta-Thalassemia in the United Arab Emirates

The beta-thalassemia alleles in 313 national patients of the United Arab Emirates (UAE) have been characterized using PCR-based DNA-diagnostic techniques including DNA sequencing. A total of 212 patients had homozygous beta-thalassemia and the remaining 101 were compound heterozygotes. More than half of the patients were homozygous for the IVS-I-5 (G-->C) mutation followed by the sickle cell gene. The latter accounted for 25% of the chromosomes. In terms of frequency, five beta-thalassemia mutations; IVS-I-5 (G-->C), betaS, -25 bp del, Cd 8/9 (+G) and IVS-II-1 (G-->A) accounted for 83% of the alleles. In addition, 427 expatriate patients were studied: 256 with homozygous beta-thalassemia and 171 were compound heterozygotes. In both the UAE nationals and expatriates, the beta-thalassemia mutations and their frequency followed a similar trend. Our results indicate that the frequency of beta-globin gene defects including beta-thalassemia, sickle cell gene (betaS) and abnormal hemoglobins is significantly increased and poses a major public health problem in the UAE. The number of homozygous patients strongly suggests a high degree of consanguinity among the UAE nationals. With 50 different beta-thalassemia alleles, UAE is arguably the most heterogeneous population in the world. The diversity of these mutations reflects the historical admixture of genes and their migration from different areas in the region. Our data strongly suggest the need for a comprehensive thalassemia control program and provides a basis for population screening, genetic counseling and prenatal diagnosis.

Hemoglobinopathies in the United Arab Emirates

The use of modern DNA techniques enabled us to characterize and identify 44 distinct beta-thal mutations and nine alpha-thal genotypes in the UAE population. All of the beta-thal mutations were severe beta+ or beta0 types resulting in transfusion-dependent phenotypes. Furthermore, a large number of alphaT alleles in the alpha-thal carriers and in patients with Hb H disease, accentuate the importance of Hb H disease as a public health problem. The overall data presented here will be useful for genetic counseling, pre-marital carrier screening and the establishment of a comprehensive prenatal diagnosis program.

alpha-thalassemia in the United Arab Emirates

A neonatal screening survey of alpha-thalassemia (alpha-thal) among the United Arab Emirates (UAE) nationals was conducted on 418 consecutive cord blood samples. Our findings demonstrate that 49% of the cases studied were found with an alpha-globin gene defect. The gene frequency of the -alpha3.7 was 0.2847 and that of the -alpha4.2 was 0.0072. Four nondeletional alpha-thal mutations were found; alphaPA-1, alphaPA-2, Hb CS and alpha-5nt del with gene frequencies of 0.0036, 0.0012, 0.0024, and 0.0072, respectively. We also report here the genotype-phenotype correlation in 22 patients with Hb H disease or Hb H-like syndrome. Of these, 6 were homozygous for the alphaPA-1 mutation, 2 were homozygous for Hb CS, and 14 were compound heterozygous for either alphaPA-1, Hb CS, alpha-5nt del or --MED-I, with the -alpha3.7. The data reported here demonstrate that a considerable heterogeneity of alpha-thal mutations occurs in the UAE and that the incidence of alpha-thal in the indigenous population is one of the highest in the world. Our clinical data suggest that Hb H disease in the UAE has, in general, a mild to moderate phenotypic presentation.

Genotype-phenotype correlation of sickle cell disease in the United Arab Emirates

We have identified the beta s-globin gene haplotypes of 85 patients with sickle cell disease attending the Dubai Thalassemia Center and assessed the influence of haplotype, alpha-thalassemia, and fetal hemoglobin on the clinical presentation. Identification of the beta s haplotypes was based on mutation analyses in the promoter sequences of the G gamma- and A gamma-globin genes. The Arabian-Indian haplotype was found in 52% of the beta s chromosomes, whereas the remaining were the Bantu and Benin haplotypes. Those with the Arabian-Indian haplotype in this group had a significantly higher fetal hemoglobin (Hb F) level (mean 27%) and a milder clinical course. In contrast, those with the African haplotypes, Bantu and Benin, expressed relatively lower Hb F levels (mean 11.3%), with a severe clinical presentation. Coinheritance of alpha-thalassemia trait in the African haplotypes had an ameliorating effect on hemolytic episodes, but vaso-occlusive crises were more frequent.

The molecular basis of Hb H disease in Turkey

A total of 25 unrelated Hb H patients were studied at the DNA level. Ten different genotypes were found to be responsible for the disease. The most prevalent alpha-thalassemia-2 determinant was the alpha alpha/-alpha (3.7) kb deletion (56%) which was followed by a nondeletional type of alpha-thalassemia, namely the pentanucleotide deletion in the 5' first intervening sequence splice junction [alpha(-5nt) alpha] (16%). The two most frequent alpha-thalassemia-1 determinants were alpha alpha/-20.5 kb and alpha alpha/-17.5 kb (MED-I) deletions. In two patients, homozygosity for the polyadenylation signal mutation [alpha (PA-2)alpha] was found to be responsible for Hb H disease. Clinical and hematological expression seems more severe in patients with the alpha (-5nt) alpha deletion at the donor site of the first intervening sequence and the alpha(PA-2) alpha mutation in trans to an alpha-thalassemia-1 determinant. Homozygosity for the alpha (PA-2)alpha mutation was also found to be associated with severe phenotype.

A large beta-thalassemia deletion in a family of Indonesian-Malay descent

The partial molecular characterization of a large deletion present in two members of an Indonesian-Malay family with beta-thalassemia trait is described. Polymerase chain reaction and sequencing analyses of the breakpoint identified a sequence which has previously been described in patients with the 45 kb Filipino beta 0-thalassemia deletion, i.e. a 5' breakpoint at position -4279 nucleotides 5' from the Cap site of the beta-globin gene. The 3' breakpoint is located in an L1 family of repetitive sequences at an unknown distance from the beta-globin gene. The hematological and hemoglobin data of the patients with this beta 0-thalassemia deletion further supports the concept that the unusually high Hb A2 levels are unique to deletions removing the 5' beta-globin gene region, and points to the importance of the 3' junction sequences for the regulation of Hb F levels in patients with deletional defects of the beta-globin gene cluster.

The relative levels of alpha 2-, alpha 1-, and zeta-mRNA in HB H patients with different deletional and nondeletional alpha-thalassemia determinants

We have analyzed the alpha 2/alpha 1-, alpha/beta-, zeta/(alpha + zeta)-mRNA ratios in the retic-ulocytes of 40 patients with Hb H disease. 21 patients had deletional Hb H disease (- -/- alpha), namely combinations of one of four types of alpha-thal-1 (MED-I, MED-II, -(alpha)20.5, SEA) and one of two types of alpha-thal-2 (-3.7 or -4.2 kb); 13 had Hb H disease because of combinations of one of these alpha-thal-1 deletions with either a 5 nt deletion at the 5' splicing site of IVS-I, or a terminating codon mutation (Hb CS), or a poly(A) mutation, and six were homozygous for either a poly(A) mutation or the 5 nt deletion. Significant differences were observed between the deletional types (- -/- alpha; alpha 2/alpha 1 ratio of zero; alpha/beta ratio of approximately 1) and non-deletional types (- -/alpha T alpha; alpha 2/alpha 1 ratio of 0.05-0.3 for those with T = the 5 nt deletion or the terminating codon mutant, and approximately 1.0 for those with T = a poly(A) mutation; alpha/beta ratio in all types of approximately 0.7). Comparable data were found for the nondeletional alpha-thal-2 homozygotes. The noted differences were highly significant and the determination of the two ratios may be diagnostically of considerable value. The low alpha 2/alpha 1-mRNA ratio in the two patients with - -/alpha-5nt alpha and the one patient with alpha-5nt alpha/alpha-5nt alpha indicates the presence of minute amounts of alpha 2-mRNA; apparently splicing at the donor site is greatly impaired by this deletion but not eliminated. The high alpha 2/alpha 1-mRNA ratio in the four patients with - -/alpha PA-2 alpha and the five patients with alpha PA-1 alpha/ alpha PA-1 alpha (PA-1 and PA-2 are poly(A) mutations) is due to the presence of an elongated alpha 2-mRNA which uses an alternate location as polyadenylation site. The relative levels zeta-mRNA varied considerably; the highest levels were found in patients with the -(alpha)20.5/-alpha or - -SEA/-alpha deletional types but not in those with the -(alpha)20.5/alphaPA-2 alpha, -(alpha)20.5/alpha-5nt alpha, or - -SEA/alphaCS alpha nondeletional types. No definitive explanation can be given for these differences; perhaps certain sequences that are part of some of the alpha-thal-1 deletions are important for the suppression of the zeta-globin gene.

Hb Costa Rica or alpha 2 beta 2 77(EF1)His --> Arg: the first example of a somatic cell mutation in a globin gene

We have identified a minor hemoglobin component (approximately 5%) in the blood of a healthy Costa Rican female, but not in her mother and two brothers (father not studied), that has an His --> Arg replacement at position beta 77 (Hb Costa Rica). No other amino acid replacements were observed and no beta- or gamma-chain-like peptides were present. Hb Costa Rica has abnormal stability. Sequence analyses of numerous polymerase chain reaction (PCR)-amplified segments of DNA that contain exon 2 of the beta gene failed to identify a CAC --> CGC (His --> Arg) mutation. The same was the case when cDNA was sequenced, indicating that a beta-Costa Rica-mRNA could not be detected with this procedure. Gene mapping of genomic DNA with Bg/II, BamHI, and HindIII gave normal fragments only and with the same intensity as observed for the fragments of a normal control. The quantities of the beta chain variants Hb J-Iran and Hb Fukuyama with related mutations at beta 77 vary between 30% and 45% in heterozygotes, whereas that of Hb F-Kennestone with the same His --> Arg mutation but in the G gamma-globin gene, is a high 40%-45% (as percentage of total G gamma) in a heterozygous newborn. These different observations exclude a heterozygosity of the A --> G mutation at codon beta 77, as well as a deletion comparable to that of Hbs Lepore or Kenya, or a beta-globin gene duplication, and point to a nontraditional inheritance of Hb Costa Rica. Allele-specific amplification of cDNA with appropriate primers identified the presence of a low level of mutated mRNA in the reticulocytes of the patient, which was confirmed by dotblot analysis of the same material with 32P-labeled probes. Comparable amplification products were not observed in genomic DNA. The A --> G mutation apparently occurred in a somatic cell at a relatively early stage in the development of the hematopoietic cell system, and Hb Costa Rica accumulated through rapid cell divisions in patchy areas in the bone marrow (somatic mosaicism). An unequal distribution of Hb Costa Rica over the red cells supports this possibility.

Hb Bibba or alpha 2 136(H19)Leu-->Pro beta 2 in a Caucasian family from Alabama

Several members of a large Caucasian family who presented with a congenital Heinz body hemolytic anemia were found to be carriers of the unstable Hb Bibba or alpha 2 136(H19)Leu-->Pro beta 2. Identification by protein analysis was hampered by the instability of the variant which complicated its isolation from shipped blood samples. Moreover, the detection of the CTG-->CCG mutation at codon 136 of the alpha 2 gene required the substitution of dGTP by dITP during the DNA sequencing process to prevent the occurrence of secondary structures and compressions in the sequencing gel. The first Hb Bibba heterozygote, characterized in 1968 (1), is believed to be a member of this family. The clinical expression of the disease is surprisingly variable.

alpha-Thalassaemia in the population of Cyprus

We have determined the alpha-thalassaemia (alpha-thal) determinants in 78 patients with Hb H disease from Cyprus; 25 were Turkish Cypriots and 53 were Greek Cypriots. Four deletional and three non-deletional alpha-thal alleles were present; the -alpha(3.7 kb) alpha-thal-2 and the --MED-I alpha-thal-1 were most frequently seen; --MED-II and -(alpha)20.5 deletions occurred at considerably lower frequencies. About 15% of all chromosomes carried a non-deletional alpha-thal-2 allele; of these the 5 nucleotide (nt) deletion at the first intervening sequence (IVS-I) donor splice site was present in approximately 8% of all chromosomes. Two types of polyadenylation signal (poly A) mutations were observed. No striking frequency differences were seen between Greek and Turkish Cypriot patients. Combinations of the various types of alpha-thal resulted in eight different forms of Hb H disease. The phenotypes were comparable except for great variations in the level of Hb H which was highest (average approximately 22%) in the 12 patients with the alpha 5nt alpha/--MED-I combination. One patient with the same form of Hb H disease but with an additional beta-thal (IVS-I-110,G-->A) heterozygosity had a most severe microcytosis and hypochromia with < 1% Hb H. Variations in the level of Hb H might correlate with the severity of the disease, although this was not evident from the haematological data.

Factors associated with hypochromia and microcytosis among high school students in the southeastern United States

We studied hematologic findings in 617 apparently healthy Georgia elementary, middle, and high school students, aged 10 to 19 years, and examined the influence of several parameters (race, sex, iron status, and genetic hemoglobin [Hb] abnormalities) on hypochromia and microcytosis, with or without anemia. Fourteen students (2%) (6 male, 8 female; 4 white, 10 black) were found to be anemic (Hb < 11.8 g/dL in boys or < 11.3 g/dL in girls). Hypochromia (mean corpuscular Hb < 25 pg) with or without microcytosis (mean corpuscular volume < 78 fL) was found in 26 students (4%). Iron deficiency was the main associated factor in white students, but in blacks genetic Hb abnormalities, especially alpha-thalassemia trait, were other predisposing factors. The overall prevalence of iron deficiency (serum ferritin < or = 12 ng/mL) was 32.4% in the entire sample population, 30.5%, among blacks, and 33.2% among whites.