Hb H Disease Diagnosed During Adolescent Pregnancy.

Hb H disease is a moderate to severe form of α-thalassemia (α-thal). Patients with Hb H disease may become symptomatic, especially during infections and pregnancy, and may require transfusions. Herein, we present a 16-year-old female with Hb H disease who was initially diagnosed during adolescent pregnancy and was found to carry the -α3.7/-(α)20.5 deletions. The relatively mild presentation of this case highlights the milder phenotypic consequences of deletional α mutations. The case describes the screening and management of pregnancy with Hb H disease. Additionally, this case demonstrates that screening of some undiagnosed inherited blood disorders is important during pregnancy.

Evaluation of Thalassaemia Screening Tests in the Antenatal and Non-Antenatal Populations in Singapore.

INTRODUCTION: Haemoglobinopathy testing is performed for carrier screening and evaluation of microcytic anaemia. We evaluated the effectiveness of thalassaemia screening tests at our institution and suggest ways of improving the testing algorithm. MATERIALS AND METHODS: A total of 10,084 non-antenatal and 11,364 antenatal samples with alkaline gel electrophoresis (AGE), capillary electrophoresis (CE), haemoglobin H (HbH) inclusion test, mean corpuscular haemoglobin (MCH) and mean corpuscular volume (MCV) were retrospectively reviewed. A subgroup of 187 samples with genetic testing was correlated with HbH inclusions and MCH/ MCV. The effect of iron deficiency on percentage hemoglobin A2 (HbA2) was studied. RESULTS: HbH inclusion test showed low sensitivity of 21.43% for α-thalassaemia mutations but higher sensitivity of 78.95% for --SEA deletion. By receiver operating characteristic (ROC) analysis, MCH ≤28 pg or MCV ≤80 fl for non-antenatal samples and MCH ≤27 pg or MCV ≤81 fl for antenatal samples had >98% sensitivity for HbH inclusions. Above these thresholds, the probability that HbH inclusions would be absent was <99% (negative predictive value [NPV] >99%). MCH ≥28 pg had 100% sensitivity (95% CI 95.63%-100%) for α-thalassaemia mutations and 97.68% calculated NPV in the antenatal population. Detection of haemoglobin variants by CE correlated highly with AGE (99.89% sensitivity, 100% specificity). Severe iron deficiency reduced HbA2 in hemoglobin (P <0.001) and α-thalassaemia (P = 0.0035), but not in ß-thalassaemia. CONCLUSION: MCH/MCV thresholds have adequate sensitivity for α-thalassaemia in the antenatal population, and genotyping plays an important role as HbH inclusion test shows low sensitivity. CE without AGE, may be used as initial screening for haemoglobin variants. Our study provides contemporary data to guide thalassaemia screening algorithms in Singapore.

Hematological Analysis in Thai Samples With Deletional and Nondeletional HbH Diseases.

OBJECTIVES: To compare hematological parameters between deletional and nondeletional HbH diseases, and to investigate the correlation between HbH levels and hematological parameters within these 2 groups. METHODS: Samples of 43 deletional HbH diseases, which included 39 --SEA/-α3.7, 4 - -SEA/-α4.2, and 22 nondeletional HbH diseases (- -SEA/αcsα), were used in this study. Correlations between HbH levels and hematological parameters within these 2 groups were analyzed. RESULTS: The deletional HbH disease had higher levels of RBC counts, total Hb, pack cell volume (PCV), mean corpuscular Hb (MCH), mean corpuscular Hb concentration (MCHC), HbA, and HbA2 than did the nondeletional HbH disease. A negative correlation between HbH and RBC counts was detected in the group of deletional HbH disease, while a positive correlation between HbH and RBC counts, total Hb, and PCV was found in the group of nondeletional HbH disease. CONCLUSIONS: These results reflected that samples with nondeletional HbH showed more anemic features than those with the deletional HbH.

Characterization of two unique α-globin gene cluster deletions causing α-thalassemia in Israeli Arabs.

The molecular basis of α-thalassemia (α-thal) is complex. The use of multiplex ligation-dependent probe amplification (MLPA) has offered the possibility of identifying more gene deletions causing α-thal. Our objective was to determine the molecular basis of two patients with Hb H (ß4) disease. By using MLPA in combination with comparative genomic hybridization (CGH) we identified two novel α-globin gene cluster deletions: a 30 kb deletion (patient 1) we refer to as - -(JAL) and a large 216 kb deletion (patient 2) we refer to as - -(LOD). Patient 1 was a compound heterozygote for - -(JAL) and -α(3.7) (rightward deletion). Twelve family members of patient 1 carrying the - -(JAL) deletion were available for evaluation: five with - -(JAL)/-α(3.7), four with - -(JAL)/α(Hph I)α and three with - -(JAL)/αα. Their clinical picture of compound heterozygosity was compatible with moderate Hb H disease. In patient 2 (- -(LOD)/-α(3.7)), no additional symptoms were present despite the heterozygous deletion of seven known genes, three non coding RNAs (ncRNAs), four unknown genes and two pseudo genes. Further analysis of more patients with α-thal deletions will have implications for genetic counseling and appropriate therapy.

A newly modified hemoglobin H inclusion test as a secondary screening for α(0)-thalassemia in Southeast Asian populations.

Screening for α(0)-thalassemia is usually associated with a high false-positive rate, leading to an unnecessary PCR workload for accurate diagnosis. We have developed a modified Hb H inclusion test for use as a secondary screening. This test was performed on young red blood cell enriched fractions using dextran sedimentation. The study was performed in 100 subjects positive on initial screening. Confirmatory tests included Hb analysis and a multiplex PCR assay to identify α(0)-thalassemia deletions. A modified Hb H inclusion test was positive in 31 cases, 30 of whom were α(0)-thalassemia carriers (97%). The remaining case (3.0%) was homozygous for α(+)-thalassemia. The remaining 69 cases with a negative Hb H inclusion test included normal subjects, α(+)-thalassemia carriers and ß-thalassemia carriers. Two of them (2/69, 3.0%) were found to be double heterozygotes for ß(0)-thalassemia and α(0)-thalassemia. The overall sensitivity and specificity of the modified Hb H inclusion test for screening of α(0)-thalassemia were 94.0 and 99.0%, respectively. Therefore, we recommend the use of this test in combination with Hb analysis to exclude cases with αß-thalassemia. This should lead to a significant reduction in the number of cases referred for PCR analysis of α(0)-thalassemia by about 50.0%.

Diagnostic applications of newborn screening for α-thalassaemias, haemoglobins E and H disorders using isoelectric focusing on dry blood spots.

BACKGROUND: Neonatal screening for haemoglobin (Hb) disorders is a standard of care in several developed countries with the main objective to detect Hb S. Such practice has not been established in Thailand where α-thalassaemia and haemoglobin E (Hb E) are highly prevalent. Early identification of thalassaemias could be helpful and strengthen the programme for prevention and control for severe thalassaemias. METHODS: Data from isoelectric focusing (IEF) and Isoscan® for detecting types and amount (%) of each haemoglobin in 350 newborn's dried blood spots were analysed and compared with the comprehensive genotype analysis by DNA studies as a gold standard. RESULTS: Based on genetic profiles, there were 10 different categories: (1) normal (n = 227), (2) α(+)-thalassaemia trait (n = 14), (3) α(0)-thalassaemia trait (n = 13), (4) ß(0)-thalassaemia trait (n = 7), (5) Hb E trait (n = 72), (6) Hb E trait with α(0)-thalassaemia or homozygous α(+)-thalassaemia (n = 5), (7) Hb E trait with α(+)-thalassaemia trait (n = 5), (8) homozygous Hb E (n = 3), (9) homozygous Hb E with α(0)-thalassaemia trait (n = 1) and (10) Hb H disease (n = 3). The presence of Hb Bart's and Hb E were used to identify cases with α-thalassaemia and Hb E, respectively. We set 0.25% of Hb Bart's and 1.5% of Hb E as a cut-off level to detect α(+)-thalassaemia trait (sensitivity 92.86% and specificity 74.0%) and Hb E trait with 100% of both sensitivity and specificity for IEF diagnosis. CONCLUSION: Although molecular diagnosis seems to be better for definitive diagnosis of thalassaemia syndromes at birth, however, using our reference range described herein, IEF can be applied in a resource-limiting setting with acceptable reliability.

Relationship between neonatal screening results by HPLC and the number of α-thalassaemia gene mutations; consequences for the cut-off value.

OBJECTIVES: To evaluate the relationship between FAST peak percentage by adapted Bio-Rad Vnbs analysis using the valley-to-valley integration and genotypes with the aim to improve differentiation between severe α-thalassaemia forms (HbH disease) and the milder disease types. METHOD: DNA analysis for α-thalassaemia was performed on 91 dried blood spot samples presenting normal and elevated FAST peak levels, selected during three years of Dutch national newborn screening. RESULTS: Significant differences were found between samples with and without α-thalassaemia mutations, regardless of the genetic profiles. No significant difference was demonstrated between HPLC in -α/αα and -α/-α, between -α/-α and - -/αα and between - -/αα and - -/-α genotypes. CONCLUSION: This study confirms that the percentage HbBart's, as depicted by the FAST peak, is only a relative indication for the number of α genes affected in α-thalassaemia. Based on the data obtained using the modified Bio-Rad Vnbs software, we adopted a cut-off value of 22.5% to discriminate between possible severe α-thalassaemia or HbH disease and other α-thalassaemia phenotypes. Retrospectively, if this cut-off value was utilized during this initial three-year period of neonatal screening, the positive predictive value would have been 0.030 instead of 0.014.

Effects of the Hb E, Hb H and Hb G-Taichung variants on HbA1c values by the Bio-Rad variant II turbo analyzer.

OBJECTIVES: The influences of Hb variants on HbA(1c) values can cause mismanagement of diabetes; therefore, the effects of Hb E, H, and G-Taichung variants were evaluated. DESIGNS AND METHODS: HbA(1c) values of 2105 samples, including 37 samples with Hb E, H and G-Taichung variants identified by Hb electrophoresis and the PCR sequence, were evaluated by the ion-exchange (Bio-Rad Variant II Turbo analyzer) and boronate affinity (Primus CLC 385 analyzer) high performance liquid chromatography (HPLC) methods. RESULTS: In the patients with the Hb E and H variants, their HbA(1c) values determined by ion-exchange HPLC were significantly higher than those by boronate affinity HPLC. However, there were no significant differences of the HbA(1c) values in the patients with the Hb G-Taichung variant. CONCLUSIONS: The HbA1c levels might be interfered by the Hb E and H variants, but not the Hb G-Taichung variant, measured by the Bio-Rad Variant II Turbo analyzer.

Hemoglobin Q-Thailand related disorders: origin, molecular, hematological and diagnostic aspects.

We describe the molecular and hematological profiles of thalassemia syndromes caused by interactions of hemoglobin (Hb) Q-Thailand [α74(EF3) Asp-His] and various hemoglobinopathies found in 52 unrelated adult Thai subjects. Ten genotypes including several previously undescribed conditions were observed, which were classified into 4 groups. Group I included 26 Hb Q-Thailand heterozygotes and a homozygotous subject. Group II included subjects with Hb Q-Thailand and other α-thalassemia alleles in trans including 1 compound Hb Q-Thailand/α(+)-thalassemia (-α(3.7)), 2 Hb Q-Thailand/Hb Constant Spring disease and 6 Hb H/Q-Thailand disease. The average levels of Hb Q-Thailand were found to be 29.8%, 82.3%, 34.7%, 49.2-49.3% and 79.4%, respectively. Both Hbs Bart's and H were observed in addition to Hb Q-Thailand in all 6 cases with Hb Q-H disease but not in a homozygous Hb Q-Thailand. Group III included 7 double heterozygotes for Hb Q-Thailand/Hb E, 3 Hb Q-Thailand/Hb E/α(+)-thalassemia (-α(3.7)), 3 heterozygous Hb Q-Thailand/homozygous Hb E and 1 triple heterozygote for Hb Q-Thailand/Hb Constant Spring/Hb E. In this group, Hbs E (α(A)(2)ß(E)(2)), Q-Thailand (α(QT)(2)ß(A)(2)) and QE (α(QT)(2)ß(E)(2)) were observed on both HPLC and capillary electrophoresis. The Hb QE, rather than Hb Q-Thailand, was detected in all 3 cases with heterozygous Hb Q-Thailand and homozygous Hb E. The remaining two cases in group 4 were double heterozygotes for Hb Q-Thailand and ß(0)-thalassemia in which Hb Q-Thailand, elevated Hb A(2) (α(A)(2)δ(2)), and Hb QA(2) (α(QT)(2)δ(2)) were detected. DNA analysis identified the Hb Q-Thailand mutation (α74: GAC-CAC) and the linked (-α(4.2)) in all cases. Analysis of α-globin gene haplotype provided the first evidence of a single origin of this Hb variant in Thai population.

Cord blood screening for alpha-thalassemia and hemoglobin variants by isoelectric focusing in northern Thai neonates: correlation with genotypes and hematologic parameters.

We describe the screening of newborns for thalassemia and Hb variants by using isoelectric focusing (IEF) in a population from northern Thailand where hemoglobinopathies are highly prevalent. The report focuses on findings of alpha-thalassemia, Hb E, and other hemoglobin variants, and their correlation with genotypes and hematologic parameters. Two-hundred and seven out of 566 newborns (36.6%) had thalassemia genes or Hb variants. Seventeen different genotypes were found. Nine cases (1.6%) of Hb H disease (five deletional Hb H diseases, two Hb H/Constant Spring diseases, one deletional Hb H disease/Hb E, carrier and one Hb H/Constant Spring disease/Hb E carrier) and one Hb E-beta-thalassemia were identified. IEF could clearly distinguish Hb H diseases and carriers of two alpha-globin gene defects from normal individuals according to the presence of Hb Bart's and its percentage. For carriers of a single alpha-globin gene defect, Hb Bart's was either absent or present in a small amount and was therefore not reliable for screening. The presence of an additional band at the Hb A(2) position in the newborns signified an Hb E carrier. One case of an absent Hb A and a presence of Hb E was identified as Hb E-beta-thalassemia. Two Hb Q-Thailand carriers were seen with two additional Hb fractions, presumably combinations of gamma-globin and beta-globin with the alpha-globin variant. Newborns with Hb H disease had lower Hb, MCV, and MCH levels than normal. MCV and MCH were also useful for differentiation of carriers of two alpha-globin gene defects, but not for carriers of Hb E or single alpha-globin gene defect. IEF was a reliable method for neonatal cord blood screening for alpha-thalassemia and Hb variants.

A multicenter trial of the effectiveness of zeta-globin enzyme-linked immunosorbent assay and hemoglobin H inclusion body screening for the detection of alpha0-thalassemia trait.

Routine laboratories use a hemoglobin H (HbH) screen to detect alpha-thalassemia carriers of fatal hemoglobin Bart's hydrops fetalis. This test is laborious and has sensitivity concerns. A commercial zeta-globin enzyme-linked immunosorbent assay (ELISA) is effective in detecting Southeast Asian (SEA) alpha-thalassemia. We present results of a study of the effectiveness of carrier detection of ELISA and a shortened HbH screen compared with gap polymerase chain reaction. ELISA was superior to the HbH screen for the SEA alpha0-thalassemia trait. The ELISA and H screen were equal for detection of all carriers encountered and combined were more effective than either test alone. A positive zeta-globin ELISA result is diagnostic of SEA alpha-thalassemia, and routine use of the zeta-globin ELISA in combination with a shortened HbH screen will improve the efficacy of prenatal screening for carriers of hemoglobin Bart's hydrops fetalis through improved detection and referral for follow-up DNA testing.

Prevalence of erythrocyte haemoglobin H inclusions in unselected patients with clonal myeloid disorders.

Patients with clonal myeloid disorders, especially myelodysplastic syndromes (MDS), may acquire alpha-thalassaemia. To estimate the prevalence of this erythrocyte phenotype, we examined brilliant cresyl blue-stained blood smears from 201 patients with neoplastic myeloid disorders and 282 controls (195 non-clonal anaemia, 62 with medical illnesses without anaemia and 25 healthy persons). Haemoglobin H inclusions were detected in 8/100 patients with MDS (8%) and 2/81 (2.5%) patients with myeloproliferative disorders, but in none of the acute leukaemia patients or controls. We conclude that the emergence of thalassaemic clones may be relatively common in the disordered marrow milieu of MDS.

Hemoglobin variants and disease manifestations in severe falciparum malaria.

CONTEXT: The geographical distributions of hemoglobin S (HbS), hemoglobin C (HbC), and alpha+-thalassemia (-alpha) strongly suggest balancing selection with malaria. However, whereas several studies indicate that the HbS carrier state protects against all major forms of clinical malaria, malaria protection on clinical grounds has been more difficult to confirm for HbC and -alpha, and questions remain as to whether it applies to all forms of the disease. OBJECTIVE: To assess the association between major clinical forms of severe falciparum malaria and HbS, HbC, and -alpha. DESIGN, SETTING, AND PARTICIPANTS: Case-control study of 2591 children with severe falciparum malaria enrolled at a tertiary referral center in Ghana, West Africa, and 2048 age-, sex-, and ethnicity-matched control participants recruited by community surveys. MAIN OUTCOME MEASURES: Frequencies of HbS, HbC, and -alpha in patients and controls, including stratifications of patients for signs of disease. RESULTS: Patients presented with partly overlapping signs of disease, including severe anemia (64%), cerebral malaria (22%), respiratory distress (30%), hyperparasitemia (32%), prostration (52%), acidosis (59%), and hyperlactatemia (56%). Carrier states of HbS, HbC, and -alpha were found in 1.4%, 9.4%, and 25.2% of the patients, respectively, and 14.8%, 8.7%, and 27.3% of controls. The HbS carrier state was negatively associated with all forms of the disease studied (overall odds ratio [OR], 0.08; 95% confidence interval [CI], 0.06-0.12). The HbC carrier state showed a negative association selectively with cerebral malaria (OR, 0.64; 95% CI, 0.45-0.91), and the -alpha carrier state showed a negative association selectively with severe anemia (OR, 0.82; 95% CI, 0.69-0.96). CONCLUSION: Whereas the HbS carrier state was found to be negatively associated with all major forms of severe falciparum malaria, the negative associations of the carrier states of HbC and -alpha appeared to be limited to cerebral malaria and severe anemia, respectively.

An improved method for the diagnostic approach of alpha+-thalassaemia.

An improved method for the diagnostic approach of alpha(+)-thalassaemia is described. The method is based on five common parameters: absence of iron deficiency, mild morphological abnormalities of erythrocytes, normal or slightly reduced erythrocytic indices MCV and MCH, normal chromatographic findings, and presence of haemoglobin H inclusions in erythrocytes with methyl-violet stain after, but not before, incubation with oxidant agent. We studied by DNA analysis, 58 subjects fulfilling the above mentioned diagnostic criteria and we found that 50 of them (86.2%) had a alpha-globin gene defect. In the remaining eight subjects (13.8%) no alpha-gene defect could be documented with the techniques used in the DNA analysis, which detect the six well-known alpha(+)-thalassaemic defects in the Greek population. We conclude that the improved method, we described has a high sensitivity and accuracy in the screening of alpha(+)-thalassaemia.

Clinical and molecular analysis of haemoglobin H disease in Sardinia: haematological, obstetric and cardiac aspects in patients with different genotypes.

In this study, 251 Sardinian patients (187 adults and 64 children) with haemoglobin (Hb) H disease were evaluated. Two-hundred and sixteen patients (86%) had the deletional type (- -/-alpha) and 36 (14%) patients had the non-deletional type (- -/alpha(ND)alpha). A clear genotype-phenotype correlation was found, with the non-deletional type more severe than the deletional type. Diagnosis of Hb H disease was incidental in about 60% of cases. Aplastic crises due to B19 parvovirus infection were found in five patients (2.1%), while 23 patients (9.6%) experienced one or more haemolytic crises. Nineteen patients with Hb H received sporadic red blood cell transfusions and three patients were repeatedly transfused. Forty-seven of 61 married women (77%) had 82 pregnancies. In children, mean serum ferritin was 87 +/-92 mug/l and in adults, was 192 +/- 180 mug/l in females and 363 +/- 303 mug/l in males. For the 98 male patients, a significant correlation was found between ferritin values and age (r2 = 0.33, P < 0.0001). In the Sardinian population, Hb H disease needs regular monitoring for early detection and treatment of possible complications, such as worsening of anaemia that may require red cell transfusion, cholelithiasis and iron overload.

Detection of alpha-thalassemia in beta-thalassemia carriers and prevention of Hb Bart's hydrops fetalis through prenatal screening.

The aim of this study was to detect alpha-thalassemia in beta-thalassemia carriers during prenatal screening. During a 12-year prenatal screening program, a total of 158 couples (3.2%) were diagnosed to be the discordant alpha- and beta-thalassemia carriers. Of the 158 beta-thalassemia partners, seven (4.4%) were found to have co-inheritance of alpha0-thalassemia, and three (1.9%) found to have co-inheritance of alpha(+)-thalassemia. Three pregnancies affected with Hb Bart's hydrops fetalis were terminated in the 158 couples. The results showed that molecular analysis must be used for accurate diagnosis of double heterozygotes in couples presumed to be discordant for alpha- and beta-thalassemia on hematologic testing.