The value of NT-pro-brain natriuretic peptide and left ventricular ejection fraction for prediction of premature ventricular complexes burden

OBJECTIVE

We aimed to investigate the relation of NT-pro BNP level and left ventricular ejection fraction with premature ventricular complex burden.

PATIENTS AND METHODS

A total of 94 patients with PVC burden > 5% (age 45.9+12.9 years, 53 males, 41 females) were included in the study. The primary outcome was PVC burden % and main prognostic factors were LVEF% and NT-Pro BNP level. Gender, age, DM, HTN, presence of symptoms, symptom duration and heart rate were used as adjustment predictor variables. We created four different linear multivariable models to compare performance measures of prognostic factors: Model-1 has gender, age, DM, HTN, symptoms and heart rate, while LVEF has been added in addition to model-1 in model-2. Model-3 included NT-Pro-BNP alongside model-1 variables, while model-4 included both LVEF and NT-Pro-BNP variables in addition to model-1 variables. Accordingly, we compare the performance (R2, likelihood ratio X2) of models.

RESULTS

The median PVC burden was 18% (IQR; 11-27). When model-1 consisting of gender, age, DM, HTN, presence of symptoms, symptomS duration and heart rate and model-2 consisting of LVEF in addition to variables of model-1 were compared, it was observed that both LRX2 and R2 values improved (likelihood ratio test p-value=0.013). Model-1 compared with model-3 which consisting of NT-pro BNP in addition to variables of model-1, and it was observed that both LRX2 and R2 values improved (likelihood ratio test p-value=0.008). However, when compared to model-1, the most significant improvement was observed in both LRX2 and R2 values in model-4 consisting of model-1 plus NT-Pro-BNP and LVEF (likelihood ratio test p-value <0.001).

CONCLUSIONS

We determined that NT-pro-BNP levels and LVEF could predict PVC burden in patients. Higher levels of NT-pro-BNP and lower LVEF values were associated with increased PVC burden.

Evaluation of the effect of bun/albumin ratio on in-hospital mortality in hypertensive COVID-19 patients

OBJECTIVE

The impact of COVID-19 infection still continues all over the world and is an important cause of mortality. The mortality rate due to infection varies between 1-5%. The mortality rate is higher in those with cardiovascular risk factors, especially in cases with hypertension. Some studies have shown that blood urea nitrogen (BUN) and albumin levels are associated with worse prognosis in patients with COVID-19. In our study, we aimed to investigate whether the BUN/albumin (BAR) ratio has an effect on in-hospital mortality in hypertensive COVID-19 patients.

PATIENTS AND METHODS

A total of 800 hypertensive COVID-19 patients, (618 of whom were alive and 182 died) were included in our study. Patients with a history of heart failure, malignancy, acute coronary syndrome, and myocarditis were excluded.

RESULTS

The median age of the study population was 69 (60-77 IQR) years, and 305 (38%) of these patients were men. There was no statistically significant difference between the patients who died during follow-up and cases that remained alive in terms of comorbidities except chronic obstructive pulmonary disease (COPD) which was significantly lower in surviving group (p=0.014). Multivariable logistic regression analysis revealed that age [OR: 1.04, CI (1.01-1.06); p=0.002], male gender [OR: 1.85, CI (1.13-3.02); p=0.010], lymphocyte count [OR: 0.63, CI (0.40-0.98); p=0.038], SaO2 [OR: 0.82, CI (0.79-0.85); p<0.001] and BAR level [OR: 1.09, CI (1.04-1.16); p=0.001] were independent predictors of in-hospital mortality. ROC analysis yielded that BAR is a better predictor of in-hospital mortality compared to albumin and BUN alone.

CONCLUSIONS

BUN, albumin, and BAR levels were found to be reliable predictors of in-hospital mortality in COVID-19 patients, and BAR was also found to be a more reliable predictor than BUN and albumin levels. Hypertension is one of the major risk factors for morbidity and mortality in COVID-19 and, BAR presents additional prognostic data in hypertensive COVID-19 patients that may direct physicians for treatment intensification.

Development of a new needle trap-based method for the determination of some volatile organic compounds in the indoor environment

Volatile Organic Compounds (VOCs) are a large group of chemicals mostly found in indoor environments such as homes and workplaces. Long term exposure to certain VOCs can cause symptoms in some individuals and therefore, monitoring and controlling air quality can help better manage chronic respiratory diseases. In this study, we aimed to develop an easy-to-use, economical, in house needle trap-based methodology to detect certain VOCs to be used for public and occupational health. For this purpose, a multi-bed (packed with PDMS/Carbopack-X/Carboxen-1000) needle trap device (NTD) was utilized for sampling, enrichment, and injection of the VOCs into the gas chromatography. The performance of the developed method was investigated for the analysis of the group known as BTEX (benzene, toluene, ethylbenzene and xylene). Operational and instrumental parameters such as sampling flow rate and relative humidity, desorption time and temperature were optimized, and the analytical figures of merit of the proposed method have indicated that very low levels of BTEX in air samples can be easily determined by this new method. Overall results have shown that multi-bed NTD offers a high sensitive procedure for sampling and analysis of BTEX in concentration range of 0.002-0.298 mg/m³ in indoor air.

Concordance in molecular genetic analysis of tumour tissue, plasma, and exhaled breath condensate samples from lung cancer patients

AIM

Lung adenocarcinoma is characterized by poor prognosis and short survival rates. Therefore, tools to identify the tumoural molecular structure and guide effective diagnosis and therapy decisions are essential. Surgical biopsies are highly invasive and not conducive for patient follow-up. To better understand disease prognosis, novel non-invasive analytic methods are needed. The aim of the present study is to identify the genetic mutations in formalin-fixed paraffin-embedded (FFPE) tissue, plasma, and exhaled breath condensate (EBC) samples by next-generation sequencing and evaluate their utility in the diagnosis and follow-up of patients with lung adenocarcinoma.

METHOD

FFPE, plasma, and EBC samples were collected from 12 lung adenocarcinoma patients before treatment. DNA was extracted from the specimens using an Invitrogen PureLink Genomic DNA Kit according to the manufacturer's instructions. Amplicon-based sequencing was performed using Ion AmpliSeq Colon and Lung Cancer Research Panel v2.

RESULTS

Genetic alterations were detected in all FFPE, plasma, and EBC specimens. The mutations in PIK3CA, MET, PTEN, SMAD4, and FGFR2 genes were highly correlated in six patients. Somatic and novel mutations detected in tissue and EBC samples were highly correlated in one additional patient. The EGFR p.L858R and KRAS p.G12C driver mutations were found in both the FFPE tissue specimens and the corresponding EBC samples of the lung adenocarcinoma patients.

CONCLUSION

The driver mutations were detected in EBC samples from lung adenocarcinoma patients. The analysis of EBC samples represents a promising non-invasive method to detect mutations in lung cancer and guide diagnosis and follow-up.

cfDNA in exhaled breath condensate (EBC) and contamination by ambient air: toward volatile biopsies

Exhaled breath is a source of volatile and nonvolatile biomarkers in the body that can be accessed non-invasively and used for monitoring. The collection of lung secretions by conventional methods such as bronchoalveolar lavage, induced sputum collection, and core biopsies is limited by the invasive nature of these methods. Non-invasive collection of exhaled breath condensate (EBC) provides fluid samples that are representative of airway lining fluids. Various volatile and nonvolatile biomarkers can be detected in volatile condensates, such as H₂O₂, nitric oxide, lipid mediators, cytokines, chemokines, DNA, and microRNAs. Studies have examined cell-free DNA (cfDNA) in plasma samples from non-small-cell lung cancer patients, offering to new insights and fostering development of the liquid biopsy. However, few studies have examined cfDNA in EBC samples. This study examined whether EBC is an appropriate source of cfDNA using housekeeping-gene-specific primer probes and quantitative real-time polymerase chain reaction in healthy subjects. Ambient (room) air is contaminated with DNA, so caution is needed. Preliminary studies indicated that volatile biopsies are becoming an important diagnostic tool in lung cancer.

Impact of right ventricular diastolic dysfunction on clinical outcomes in inferior STEMI

BACKGROUND

The aim of this study was to investigate the prognostic value of restrictive right ventricular filling pattern (RRVFP) in patients with the first acute inferior wall myocardial infarction (IWMI) complicated by right ventricular myocardial infarction (RVMI) undergoing primary percutaneous coronary intervention (p-PCI).

METHOD

A total of 152 patients with acute IWMI complicated by RVMI undergoing p‑PCI were divided into two groups according to the presence of RRVFP. RRVFP was defined as tricuspid diastolic early/late flow velocities (Et/At) > 2 and Et deceleration time (DT) < 120 ms.

RESULTS

There were 23 patients with RRVFP in the study cohort. At, DTt, isovolumetric relaxation time (IVRT), and tissue Doppler tricuspid annular late velocity (A't) were reduced significantly in patients with RRVFP than in those without RRVFP (At 19.6 ± 2.7 vs. 39.1 ± 7.4 cm/s, p < 0.001; DTt 106 ± 13 vs.156 ± 21 ms, p = 0.001; IVRT 59 ± 6.7 vs. 62 ± 7.4 ms, p = 0.01; A't 4.6 ± 1.1 vs. 8.6 ± 1.05, p = 0.001). Et/At ratios were higher in patients with RRVFP than in those without RRVFP (Et/At 2.20 ± 0.2 vs. 1.15 ± 0.37, p < 0.001). Et, tissue Doppler tricuspid annular early velocity (E't), E't/A't ratio, and Et/E't ratio were not significantly different between groups (Et 43.3 ± 5.4 vs. 40.7 ± 9.2 cm/s p = 0.18; E't 8.8 ± 1.4 vs. 9.5 ± 2.3, p = 0.15; E't/A't 1.08 ± 0.24 vs. 1.13 ± 0.30, p = 0.52; Et/E't ratio 5.0 ± 1.1 vs. 4.5 ± 1.5 p = 0.09). Presence of E't/A't > 2, short DTt, RRVFP, unsuccessful p‑PCI, and cardiogenic shock on admission were independent predictors of in-hospital mortality (p < 0.05) in multivariable logistic regression analysis.

CONCLUSION

Presence of RRVFP is associated with in-hospital mortality in patients presenting with their first IWMI complicated by RVMI.

Auditory changes in acromegaly

OBJECTIVE

The aim of this study is to determine the changes involving auditory system in cases with acromegaly.

MATERIALS AND METHODS

Otological examinations of 41 cases with acromegaly (uncontrolled n = 22, controlled n = 19) were compared with those of age and gender-matched 24 healthy subjects. Whereas the cases with acromegaly underwent examination with pure tone audiometry (PTA), speech audiometry for speech discrimination (SD), tympanometry, stapedius reflex evaluation and otoacoustic emission tests, the control group did only have otological examination and PTA. Additionally, previously performed paranasal sinus-computed tomography of all cases with acromegaly and control subjects were obtained to measure the length of internal acoustic canal (IAC).

RESULTS

PTA values were higher (p < 0.001 for right ears and p = 0.001 for left ears), and SD scores were (p = 0.002 for right ears and p = 0.002 for left ears) lower in acromegalic patients. IAC width in acromegaly group was narrower compared to that in control group (p = 0.03 for right ears and p = 0.02 for left ears). When only cases with acromegaly were taken into consideration, PTA values in left ears had positive correlation with growth hormone and insulin-like growth factor-1 levels (r = 0.4, p = 0.02 and r = 0.3, p = 0.03). Of all cases with acromegaly 13 (32%) had hearing loss in at least one ear, 7 (54%) had sensorineural type and 6 (46%) had conductive type hearing loss.

CONCLUSION

Acromegaly may cause certain changes in the auditory system in cases with acromegaly. The changes in the auditory system may be multifactorial causing both conductive and sensorioneural defects.

Value of the neutrophil-to-lymphocyte ratio in predicting post-pericardiotomy syndrome after cardiac surgery

OBJECTIVE

Post-pericardiotomy syndrome (PPS) occurs in 10-40% of patients after cardiac surgery. PPS is considered an autoimmune phenomenon. The neutrophil-to-lymphocyte ratio (NLR) is a novel inflammatory marker that is associated with various cardiovascular diseases. Studies have reported that the NLR increases in certain autoimmune diseases. This study examined whether the NLR is helpful to predict the occurrence of PPS after elective on-pump coronary artery bypass graft (CABG) surgery.

PATIENTS AND METHODS

The records of patients who underwent elective first-time on-pump CABG were reviewed retrospectively. In total, 72 patients with PPS were included in the study, and 100 patients who did not develop PPS were included as the control group. Peripheral blood samples collected preoperatively and on postoperative day 1 were used to calculate the NLR.

RESULTS

No differences in preoperative white blood cell (WBC) count, neutrophil count, lymphocyte count, or NLR were observed between the patients with PPS and the control group. The WBC (p < 0.001) and neutrophil counts (p < 0.001) and NLR (p = 0.01) were significantly higher during the postoperative period in patients with PPS than in the control group. A receiver operating characteristic curve analysis showed that the postoperative NLR predicted PPS with 60% sensitivity and 59% specificity (area under the curve, 0.61; 95% confidence interval [CI], 0.51-0.70; p = 0.017), using a cut-off of 8.34. The postoperative WBC count (odds ratio [OR], 1.6; 95% CI, 1.36-2.03; p < 0.001) and NLR (OR, 3.3; 95% CI, 1.56-7.01; p = 0.002) were independently associated with PPS.

CONCLUSIONS

The postoperative NLR may be useful to predict the development of PPS in patients undergoing on-pump CABG.

Role of methylprednisolone in the prevention of postpericardiotomy syndrome after cardiac surgery

OBJECTIVE

Postpericardiotomy syndrome (PPS) occurs in 10-40% of patients after cardiac operations. Pericardial effusions and tamponade occurring > 7 days after surgery are usually related to PPS and remain an important cause of cardiac surgery-related morbidity and mortality; therefore, preventing PPS is important. Colchicine affords safe and efficacious protection against PPS and related complications. However, the roles of corticosteroids and nonsteroidal anti-inflammatory drugs in PPS prevention remains unclear. This study aimed to determine whether the intraoperative use of single-dose methylprednisolone can effectively prevent PPS.

PATIENTS AND METHODS

This retrospective study included 100 patients undergoing elective coronary artery bypass grafting (CABG) who received a single intraoperative dose of 1 mg/kg methylprednisolone. A further 100 patients undergoing CABG, who were not given methylprednisolone, comprised the control group. The presence and severity of pericardial effusion was determined by echocardiography, with chest X-ray used to assess pleural effusion.

RESULTS

PPS occurrence and pericardial effusion occurrence were significantly lower in patients who received methylprednisolone (p = 0.02 and p = 0.007 respectively). Although the differences were not statistically significant, pericardial and pleural effusions were more severe in the control group than in the methylprednisolone group. Logistic regression analysis demonstrated that methylprednisolone administration was independently associated with prevention of PPS (OR 0.8, 95% CI 0.25-0.91, p <  0.026).

CONCLUSIONS

Intraoperative, single-dose methylprednisolone may confer protection against PPS in patients undergoing CABG.

Serum paraoxonase, arylesterase activity and oxidative status in patients with obstructive sleep apnea syndrome (OSAS)

INTRODUCTION

The aim of this study was to evaluate the serum paraoxonase (PON), arylesterase activities, lipid hydroperoxide (LOOH), sulfhydryl (-SH), and ceruloplasmin (Cp) levels, total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) in adults with obstructive sleep apnea syndrome (OSAS) and to determine whether these oxidant and antioxidant levels can be used as OSAS markers. The results were compared with measurements from healthy control subjects.

METHODS AND METHODS

This study was a prospective, controlled trial including 26 OSAS patients and 35 healthy controls (61 subjects total). Peripheral venous blood samples were taken from the OSAS patients and from the healthy volunteers. The serum PON, arylesterase activities LOOH, -SH, Cp, TAS, TOS, and OSI levels were measured.

RESULTS

LOOH and Cp levels were higher in the OSAS group than in the control group (p < 0.01). The -SH levels were lower in the OSAS group than in the control group (p < 0.01). The PON and arylesterase enzyme activity levels were lower in the OSAS group than in the control group (p < 0.05). The TOS and OSI levels were significantly higher in the OSAS group (p < 0.01), while their TAS levels were significantly lower (p < 0.01) compared with the control group.

CONCLUSIONS

Patients with OSAS have increased systemic oxidative stress and reduced levels of circulating antioxidant enzymes. Oxidative stress appears to be an underlying condition associated with OSAS.

The role of high frequency tympanometry in newborn hearing screening programme

BACKGROUNDS AND OBJECTIVE

The hearing assessment of the newborns ideally should detect both middle and inner ear functions. The aim of this study is to control the association between otoscopic evaluation, multifrequency tympanometry and TEOAE results.

METHODS

Fifty new-borns otherwise healthy were tested after the otolaryngological evaluation by 226 and 1000 Hz tympanometries and transient evoked otoacoustic emissions (TEOAE's). The study was performed in three steps and 17 babies that could not pass from the first step they were tested in the second step with the same tests (226 Hz and 1000 Hz tympanometry and TEOAE) The babies that could not pass from the second step were evaluated by multifrequency tympanometries, TEOAE and acoustic brainstem responses (ABR) at the third step.

RESULTS

The association between the results obtained from otoscopic evaluation, multifrequency tympanometry and TEOAE were assessed. We found that 1000 Hz tympanometry results were more sensitive and gives more correlated with TEOAE and otoscopic evaluation.

CONCLUSIONS

Multifrequency tympanometry can detect the middle ear pathologies of the infants sensitively and should be a part of neonatal hearing screening test battery.

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。

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.

Beta-thalassemia alleles and unstable hemoglobin types among Russian pediatric patients

A recently initiated collaboration between Russian and American institutions has resulted in the characterization of several known or new beta-thalassemia alleles and unstable hemoglobin types. Nine known beta-thalassemia alleles were present which have also been found in Mediterranean, East Asian, and Black populations; the possibility of independent mutations for some of the rare alleles should be considered. Hb Durham-N.C./Brescia with a codon 114 (CTG-->CCG; Leu-->Pro) change was present in six members of two families. This condition and two new variants have the characteristics of a dominant type of beta-thalassemia heterozygosity with moderate anemia, Heinz body formation, splenomegaly, etc. One new beta-thalassemia allele is a frame-shift at codon 124 (-A), while another is characterized by the introduction of an extra proline residue (codon: CCA) between residues Thr (beta 123) and Val (beta 126) to give the sequence -Thr-Pro-Pro-Pro-Val-.

Detection of common deletional alpha-thalassemia-2 determinants by PCR

We have developed a rapid approach to detect the two most common alpha-thalassemia-2 (alpha-thal-2) determinants by the polymerase chain reaction (PCR) technique, which takes a few hours to complete. Specific oligonucleotides selectively amplify appropriate segments of the chromosome with the deletion and the normal chromosome under identical experimental conditions, and the products are identified by electrophoresis on 1.5% agarose. Characterization of the two most prevalent types of the -alpha 3.7 determinant [-alpha 3.7(I) and -alpha 3.7(II)] can be made by Apa I digestion of the PCR product. Two types of alpha-thal-2 determinants, -alpha 3.7 and -alpha 4.2, were tested in numerous samples from various parts of the world. This approach is believed to provide a cost-effective way to screen large numbers of blood samples in a relatively short time and can be used to identify alpha-thal-2 heterozygotes and homozygotes and compound heterozygotes (-alpha 3.7/-alpha 4.2) in populations where such alpha-gene defects are shown to exist at high frequencies.

Distribution of beta-thalassemia mutations in three Asian Indian populations with distant geographical locations

We have identified the beta-thalassemia alleles in 47 pediatric patients with transfusion-dependent thalassemia major from a clinic in New Delhi and in 105 heterozygous relatives. Surprisingly, only five mutations were present in 94 beta-thalassemia chromosomes with frequencies from 10 to 32%. This observation greatly facilitated the initiation of a prenatal diagnostic program. Similar studies were conducted for seven Asian Indian patients from Calgary, Canada, seven Asian Indian patients from Durban, South Africa, and from heterozygous relatives, and persons with a beta-thalassemia trait who were not related. Besides beta-thalassemia alleles, common to Asian Indian beta-thalassemia patients, some unexpected alleles were observed in the patients from South Africa, including a newly discovered frameshift at codon 15 (-T).

Possible factors influencing the haemoglobin and fetal haemoglobin levels in patients with beta-thalassaemia due to a homozygosity for the IVS-I-6 (T-->C) mutation

We have collected haematological, haemoglobin (Hb) and DNA sequence data for 29 patients with a homozygosity for the IVS-I-6 (T-->C) mutation with the intention of identifying factors contributing to the observed variability in the severity of the disease. None of the patients had received blood transfusion therapy for at least 6 months prior to the study. Hb levels varied from 5.0 to 9.9 g/dl. Patients with high Hb F (more than 1.5 g/dl or > 20%) had high total Hb levels (7.5-9.7 g/dl) but some with low Hb F also had high total Hb levels; two had a concomitant alpha-thalassaemia-2 (alpha-thal-2) heterozygosity. An inverse correlation between the Hb F and Hb A2 levels was observed. The majority of the patients were homozygous for haplotype VI (49/58 chromosomes) but haplotypes IV (2/58) and VII (7/58) were also present. The only haplotype IV homozygote had high Hb F levels with high G gamma values and the C-->T mutation at position -158 in the G gamma promoter, while both high and low Hb F levels were observed among patients with haplotypes VI and VII. Analysis of sequence variations in regulatory regions included the 5' hypersensitive sites (HS) 4. 3 and 2 of the locus control region (LCR), the G gamma and A gamma 5' flanking regions, the second intervening sequence (IVS-II), and the 5' beta-globin gene region in two patients with high Hb F (one homozygote each for haplotypes VI and IV), and in two patients with low Hb F levels (one homozygote each for haplotypes VI and VII). Haplotype specific differences were observed in the LCR 5' HS-2 and in the G gamma and A gamma flanking and IVS-II regions; however, no differences were present between the low and high Hb F-producing haplotype VI chromosomes, suggesting a major role for factors which are not linked to the beta-globin gene cluster in mediating gamma-globin gene expression in patients with this type of beta-thal.

Sickle cell anemia, sickle cell beta-thalassemia, and thalassemia major in Albania: characterization of mutations

We have analyzed the hemoglobin abnormalities in nearly 50 Albanian patients with a significant hemoglobinopathy and included 37 relatives in this study. Sickle cell anemia (SS) is a common disorder; all 15 sickle cell anemia patients had the complications expected for this disease. The beta S haplotype was type 19 (Benin); alpha-thalassemia-2 was rare. Three beta-thalassemia alleles (IVS-I-110, G-->A; codon 39, C-->T; IVS-I-6, T-->C) were present in nearly 85% of the beta-thalassemia alleles; their frequencies were intermediate between those observed in the populations of neighboring countries. A few rare mutations were also found, which might have originated in India, Turkey, Macedonia, and Greece. Nearly all patients with Hb S-beta-thalassemia had the IVS-I-110 (G-->A) mutation. The frequencies of 11 beta-thalassemia mutations in 17 mostly Mediterranean countries have been reviewed.

A novel deletion of approximately 27 kb including the beta-globin gene and the locus control region 3'HS-1 regulatory sequence: beta zero-thalassemia or hereditary persistence of fetal hemoglobin?

A novel deletion of approximately 27 kb with the 5' breakpoint 1.5 to 2.2 kb upstream of the beta-globin gene, and the 3' breakpoint approximately 24 kb downstream of the beta-globin gene, has been found in five members of two families from Southeast Asia (Vietnam and Cambodia). Six members of another family from China, previously reported from our laboratory, have also been shown to carry this deletion. The patients presented with mild hypochromia and microcytosis, a hemoglobin (Hb) A2 level of approximately 4.0%, and a markedly increased, heterocellularly distributed, Hb F level (14.0 to 26.0%). In vitro globin-chain synthesis showed a mild imbalance with appreciable gamma-chain compensation (alpha/beta + gamma ratio of 1.46). The 3' end of this deletion includes the 3'HS-1, and we hypothesize that removal of this region results in the loss of its gamma-globin gene-silencing effect, which causes a markedly elevated Hb F level with a modest increase in Hb A2 levels, unlike the situation in other deletional beta zero-thalassemias. The possible influence of particular sequence variations in the locus control region 5'HS-2 and the G gamma promoter, present on the chromosome with this deletion, on the overall gamma-globin gene should also be considered.

Molecular characterization of alpha-thalassemia determinants, beta-thalassemia alleles, and beta S haplotypes among Kuwaiti Arabs

Using amplification, allele-specific oligonucleotide (ASO) hybridization and DNA sequencing we have documented the molecular basis of 64 alpha- and 123 beta-thalassemia (thal) chromosomes, and the haplotypes of 18 beta S chromosomes from patients followed in three hospitals in Kuwait. Of the 30 chromosomes from 15 patients with Hb H disease, 26 (86.7%) carried the polyadenylation (poly A) signal mutation (AATAAA-->AATAAG) in the alpha 2-globin gene, 3 (10%) had the -alpha (3.7 kb) deletion, and 1 (3.3%) had the pentanucleotide deletion in the 5' IVS-I splice junction (alpha-5nt alpha). As many as 12 different beta-thal mutations were identified; 6 Mediterranean alleles [IVS-II-1 (G-->A), IVS-I-6 (T-->C), codon (CD) 39 (C-->T), IVS-I-110 (G-->A), CD 8 (-AA), and IVS-I-1 (G-->A)] were present in 79 (64.2%) of the chromosomes tested. Four East Indian alleles [IVS-I-5 (G-->C), IVS-I 3' end -25 nt deletion, CDs 8/9 (+G), and 619-bp deletion] were found in 31 (25%), and the two Kurdish/Iranian alleles [CD 44 (-C) and CDs 36/37 (-T)] were found in 13 (10.6%) chromosomes. Fourteen beta S chromosomes carried haplotype No. 31 (Saudi Arabia/India); 3 had haplotype No. 19 (Benin), and 1 was a hybrid with haplotype No. 31-specific characteristics in the locus control region hypersensitive site-2 (LCR-HS-2), and haplotype No. 19-specific mutations in the 5' flanking region of the G gamma-promoter. The patient homozygous for haplotype No. 19 was a Jordanian, while the others were Kuwaiti Arabs. The latter appear to be fairly homogeneous in terms of the prevalent alpha-thal determinants and beta S-haplotypes, but there is considerable heterogeneity of their beta-thal alleles. This has implications for genetic counseling and prenatal diagnosis programs.

The T-->C mutation at position +96 of the untranslated region 3' to the terminating codon of the beta-globin gene is a rare polymorphism that does not cause a beta-thalassemia as previously ascribed

We have observed a T-->C mutation at position +96 of the untranslated region 3' to the terminating codon of the beta-globin gene in members of two Czech families and one black family. Data from initial studies suggested that this change was the cause of a beta-thalassemia, but continued analyses have provided convincing evidence that this mutation is a simple polymorphism.

Polymorphic pattern of the (AT)X(T)Y motif at -530 5' to the beta-globin gene in over 40 patients homozygous for various beta-thalassemia mutations

Nucleotide sequence analysis of the 5' beta-globin gene flanking region has been carried out for numerous homozygous beta-thalassemia patients with different mutations and of various ethnic backgrounds. Four different rearrangements were found associated with numerous beta-thalassemia mutations. The (AT)X(T)Y repeat motif at -530 showed polymorphic patterns among these patients as follows: All ten IVS-II-1 (G-->A) chromosomes and the two with the -87 (C-->G) mutation are associated with the (AT)9(T)5 rearrangement, while the 30 IVS-I-6 (T-->C), the 16 codon 39 (C-->T), the six codon 8 (-AA) chromosomes, and 12 chromosomes with different promoter mutations had the (AT)7(T)7 motif. Six chromosomes with the promoter mutation at position -29 (A-->G) had the (AT)8(T)6 motif, while an (AT)8(T)4 motif appears characteristic for two IVS-I-5 (G-->A and G-->T). No direct association between any of the (AT)X(T)Y arrangements and an increased gamma gene expression [G gamma and fetal hemoglobin (Hb F)] levels could be demonstrated, suggesting that variations in the (AT)X(T)Y motif are common polymorphisms.

Quantities of alpha Q chain variants in heterozygotes with and without a concomitant beta-thalassemia trait

We have analyzed the quantities of alpha x chain-containing hemoglobins (alpha 2 x beta 2 and alpha 2 x delta 2) in 14 heterozygotes for Hb Q-India [alpha 64(E13)Asp-->His] or Hb Q-Thailand [alpha 74(EF3)Asp-->His]; both amino acid replacements are the result of mutations in the alpha 1-globin gene. Five of these persons (three with Hb Q-India and two with Hb Q-Thailand) had an additional beta(0)-thalassemia heterozygosity. The average quantities for Hb Q + Hb Q2 in the four groups were 17.2% (alpha alpha Q/alpha alpha; beta A/beta A), 9.5% (alpha alpha Q/alpha alpha; beta A/beta(0) Th), 26.8% (-alpha Q/alpha alpha; beta A/beta A), and 16.95% (-alpha Q/alpha alpha; beta A/beta(0) Th). These variations can best be explained by a posttranslational control mechanism; an imbalance in the alpha A, alpha Q, and beta A chain ratio will favor the alpha 2 Q beta 2 formation when an alpha-thalassemia is present and will reduce its formation in the presence of a beta-thalassemia heterozygosity.

Binding of nuclear factors to the proximal and distal CACCC motifs of the beta-globin gene promoter: implications for the -101 (C-->T) 'silent' beta-thalassemia mutation

We have used the gel retardation assay to investigate the binding of nuclear proteins to the duplicated CACCC boxes in the beta-globin gene promoter region. The effect of beta-thalassemia mutations affecting both of these consensus sequences (the -88 C-->T and -101 C-->T mutations) were studied by using appropriate mutant oligonucleotides. Upon incubation with nuclear proteins from human erythroleukemia cells, the synthetic oligonucleotides containing single and/or duplicated CACCC box(es) generated five retarded bands. Bands B1 and B2 appeared to be highly specific complexes as determined by competition experiments whereas bands B3, B4 and B5 were nonspecific. The binding of the specific trans-acting factors was stable and could be competed out only by relatively high concentrations of competitor DNA. The proximal CACCC box (as in the -88N probe) appeared to be essential in the binding of nuclear proteins and a mutation at nt -88 (C-->T) abolished binding completely. In contrast, the distal CACCC box showed no binding activity either as normal (-101N) or as mutant (-101M). A full competition with the Sp1 oligonucleotide, even at low concentrations, suggested a high affinity binding to the Sp1 consensus sequence. The close similarities in the binding patterns of the labelled -88N, -88N/-101N and that of the labelled Sp1 probe add further credence to the possibility that bands B1 and B2 may be due to the Sp1 protein, a ubiquitously expressed trans-activator.

Hb Adana or alpha 2(59)(E8)Gly-->Asp beta 2, a severely unstable alpha 1-globin variant, observed in combination with the -(alpha)20.5 Kb alpha-thal-1 deletion in two Turkish patients

We have identified a severely unstable hemoglobin variant through sequencing of amplified DNA involving the alpha 1-globin gene; the mutation is located in codon 59 (CCG CAG) and results in a Gly-->Asp replacement. This amino acid substitution concerns a glycine residue at an internal position in the E helix, which is in close contact with a glycine residue of the B helix; introduction of the larger and charged aspartic acid residue greatly affects the stability of the molecule. This variant was present in association with a common alpha-thalassemia-1 deletion [-(alpha)20.5 kb] in two adults and caused a severe type of Hb H disease with anemia, low levels of Hb A2, increased zeta chain, and Hb Bart's. In vitro chain synthesis in reticulocytes showed a high specific activity of the variant alpha chain. Only a minute quantity of Hb H was present but instead about 10% of Hb Bart's was observed. The increased synthesis of gamma chains was likely due to specific characteristics of a chromosome with haplotype #3, which was present in both patients. The same family was studied 18 years ago; the improved methodology presently available has led to a corrected diagnosis for these patients.

An IVS-I-117 (G-->A) acceptor splice site mutation in the alpha 1-globin gene is a nondeletional alpha-thalassaemia-2 determinant in an Indian population

In 1991 we reported the identification of two deletional alpha-thalassaemia-2 determinants (-3.7 kb and -4.2 kb) and one nondeletional alpha-thalassaemia-2 determinant (Hb Koya Dora alpha 2 codon 142, TAA-->TCA) in a tribal population in Central India (Gupta et al, 1991). Evidence was obtained at that time for the possible presence of an additional nondeletional alpha-thalassaemia-2 because of low levels of Hb S (< 28%) in some Hb S heterozygotes with a simple alpha-thalassaemia-2 heterozygosity (-alpha/alpha alpha). This abnormality has now been identified as a G-->A mutation at IVS-I-117 of the alpha 1-globin gene (acceptor splice site) which makes this gene nonfunctional. Its frequency was established at approximately 6% which raises the total frequency of alpha-thalassaemia determinants in this population to approximately 60%. Subjects with a deletional alpha-thalassaemia-2 and the newly discovered alpha 1 acceptor splice junction mutation in trans appear to have an alpha chain deficiency similar to that of an alpha-thalassaemia-2 homozygote (-alpha/-alpha). An additional change (C-->G) at the Cap -4 site was observed in six alpha 1- and one alpha 2-globin genes; this polymorphism is not associated with a decrease in alpha chain synthesis and is not linked to the IVS-I-117 (G-->A) mutation.

A mild type of Hb S-beta(+)-thalassemia [-92(C-->T)] in a Sicilian family

Hematological data are presented for an adult Sicilian patient with a mild Hb S-beta(+)-thalassemia caused by a C-->T mutation at position -92 of the beta promoter. This mutation was identified by sequencing of amplified DNA and was confirmed by dot-blot analysis with specific probes. A comparison of levels of Hb S and Hb A in Hb S-beta-thalassemia patients with different beta-thalassemia alleles showed great variations; the highest level of Hb A (45%) was recorded in the patient with Hb S-beta(+)-thalassemia [-92(C-->T)] and the lowest (approximately 13%) in patients with Hb S-beta(+)-thalassemia [IVS-II-745 (C-->G)]. Clinical severity is directly related to the level of Hb A present.

Beta-thalassemia mutations in the Portuguese; high frequencies of two alleles in restricted populations

We report the characterization of seven different beta-thalassemia mutations in 131 newly diagnosed Portuguese beta-thalassemia heterozygotes. Methodology included the detection of abnormal fragments by agar gel electrophoresis of PCR-amplified DNA fragments after digestion with specific restriction endonucleases, as well as hybridization with synthetic nucleotide probes and sequencing of amplified DNA. Four mutations, including the newly discovered TGG-->TGA change at codon 15, occurred in excess of 10% and accounted for some 90% of the beta-thalassemia alleles in this population. The geographical distribution is uneven; the TGG-->TGA mutation at codon 15 was primarily observed in the coastal region north of Lisbon, while the IVS-I-6 (T-->C) mutation was confined to the central part of the country.