Case report: Effect of Hb E heterozygosity on HbA1c value by the Tosoh HLC-723G11

Objective

We report the effect of Hb E heterozygosity on HbA1c value by the Tosoh HLC-723G11.

Case report

A 45 years-old Chinese woman presented with an abnormally low HbA1c level of 3.7% (3.9%-6.1%) in a health examination. Fasting blood glucose was normal. Blood routine examination and serum bilirubin were in the normal range. HbA1c was determined by Tosoh HLC-723G11. There was an abnormal peak between A1c and A0 on the chromatogram. Hemoglobin electrophoresis indicated that the Hb E zone accounted for 25.1%. The β-thalassemia-related genes (mutant type) were βE M/N, and the related gene CD26 (A > G) was mutated. OGTT indicated prediabetes.

Conclusion

Hb E heterozygosity may reduce HbA1c value with abnormal chromatograms, as determined by a Tosoh HLC G11 analyzer. The Tosoh HLC G11 analyzer can well identify Hb E variation. In this case, further blood glucose-related tests should be performed to avoid missed diagnoses. However, a large sample size is needed to confirm this conclusion.

Phenotypic Expression of Known and Novel Hemoglobin A2-Variants, Hemoglobin A2-Mae Phrik [Delta 52(D3) Asp > Gly, HBD:c.158A > G], Associated with Hemoglobin E [Beta 26(B8) Glu > Lys, HBB:c.79G > A] in Thailand

The interactions of δ-globin variants with α- and β-thalassemia or other hemoglobinopathies cause complex thalassemic syndromes and potential diagnostic problems. Understanding the molecular basis and phenotypic expression is crucial. Four unrelated Thai subjects with second hemoglobin (Hb) A2 fractions were studied. A standard automated cell counter was used to acquire initial hematological data. Hb analysis was carried out by capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) assays. Globin gene mutations and haplotype were identified by appropriate DNA analysis. An allele-specific polymerase chain reaction method was developed to provide a simple molecular diagnostic test. Hb analysis revealed a Hb A2 variant in all cases. DNA analysis of the δ-globin gene identified the Hb A2-Melbourne [δ43(CD2)Glu > Lys] variant in combination with Hb E in three cases. Analysis of the remaining case identified a novel δ-Hb variant, namely Hb A2-Mae Phrik [δ52(D3)GAT > GGT; Asp > Gly], found in association with Hb E and α+-thalassemia, indicative of the as yet undescribed combination of triple heterozygosity of globin gene defects. An allele-specific PCR-based assay was successfully developed to identify this variant. The β-haplotype of the Hb A2 Mae-Phrik allele was strongly associated with haplotype [+ − − − − ± +]. This study advanced our understanding of the phenotypic expression of known and novel δ-Hb variants coinherited with other globin gene defects, routinely causing problems with diagnosis. Therefore, knowledge and recognition of this Hb variant and molecular assessments are crucial to improving diagnosis.

Strong Positive Dichlorophenolindophenol Precipitation Suggests Hb Dhonburi (or Hb Neapolis) (HBB: c.380T>G) Inheritance in a Couple at Risk for Severe β-Thalassemia

Hb Dhonburi (also known as Hb Neapolis) (HBB: c.380T>G) is an unstable hemoglobin (Hb) variant that cannot be detected by high performance liquid chromatography (HPLC) or capillary electrophoresis (CE) in routine laboratory diagnosis. This could lead to prenatal misdiagnosis unless a molecular analysis is applied. Here, we report a Thai couple with a positive result for the dichlorophenolindophenol precipitation (DCIP) screening test. After routine laboratory investigation, the female was diagnosed with heterozygous Hb E (HBB: c.79G>A) during pregnancy; however, the male, whose case we present herein, was suspected to carry a rare heterozygous β-thalassemia (β-thal). Therefore, they were designated as a couple at-risk for having a fetus with a serious thalassemia genotype: compound heterozygosity for Hb E with β-thal (Hb E/β-thal). Based on the result of the DCIP test, his DNA was sequenced for a causative mutation and revealed heterozygosity for a rare Hb variant, Hb Dhonburi. Theoretically, this couple was not at risk for Hb E/β-thal. Furthermore, this case demonstrates for the first time that in addition to a common Hb variant, i.e. Hb E, Hb Dhonburi (Hb Neapolis) also gives positive DCIP results, even in the heterozygous state.

Clinical Severity of β-Thalassemia Pediatric Patients in Myanmar

β-Thalassemia (β-thal) is highly prevalent in Myanmar, but limited data are available on the molecular basis and the clinical manifestations in Myanmar patients. In this study, we investigated the clinical features and β-globin gene abnormalities in 15 homozygous β-thal and 60 Hb E (HBB: c.79G>A)/β-thal pediatric patients who attended Yangon Children Hospital, the biggest thalassemia day care unit center in Myanmar. Eight different β⁰-thal mutations were identified, with four accounting for 88.9% of alleles studied (excluding the Hb E variant). A genotype-phenotype correlation was found; all homozygous β⁰-thalassemias had severe clinical courses, whereas the highly variable disease severity was demonstrated among Hb E/β⁰-thal patients. Interactions of IVS-I-1 (G>T) (HBB: c0.92+1G>T) β⁰-thal with Hb E are associated with milder clinical symptoms. The number of mildly affected Hb E/β-thal patients was lower than expected, suggesting that there may be a considerable number of patients in the population who have either not been admitted to hospital or diagnosed with carrying the disease. Although the clinical severity in the Myanmar β-thal patients seems to be similar to that in other populations, the levels of hemoglobin (Hb) appears to be very low. These findings indicate the need for the improvement of patient management and the development of prevention and control programs for β-thal in Myanmar.

Prevalence of Thalassemia and Glucose-6-Phosphate Dehydrogenase Deficiency in Newborns and Adults at the Ramathibodi Hospital, Bangkok, Thailand

Thalassemias and glucose-6-phosphate dehydrogenase (G6PD) deficiency are the most common inherited blood disorders. They are distributed among populations living in malaria endemic regions resulting in survival advantage from severe malaria disease. The aims of this study were to analyze the prevalence of thalassemias and G6PD deficiency at the Ramathibodi Hospital, Bangkok, Thailand. A total of 616 adult and 174 cord blood samples were collected and analyzed for red blood cell (RBC) parameters, hemoglobin (Hb) typing and DNA analysis for G6PD mutations and α-thalassemia (α-thal). The two most prominent types of thalassemia were heterozygous Hb E (HBB: c.79G>A), (19.5% in newborns and 35.6% in adults) followed by heterozygous α-thal-2 [-α^3.7 (rightward) deletion] at 18.7% in newborns and 19.5% in adults. After performing G6PD genotyping using multiplex amplification refractory mutation system-polymerase chain reaction (multiplex ARMS-PCR) for 10 G6PD mutations, the prevalence of G6PD mutation was found in 12.0% of newborns and 11.7% of adults. The G6PD Viangchan [871 (G>A)] is the most common G6PD mutation in newborns (42.9%) and adults (52.8%). In addition, coinheritance of various types of thalassemia with G6PD deficiency were found. The results indicated that heterozygous Hb E and G6PD Viangchan are predominant both in newborns and adults in this study.

Comparison of the characteristics of two hemoglobin variants, Hb D-Iran and Hb E, eluting in the Hb A2 window

Background

Cation exchange-high performance liquid chromatography (CE-HPLC) is most commonly used to evaluate hemoglobin (Hb) variants, which elute in the Hb A2 window. This study aimed to assess prevalence of an uncommon Hb variant, Hb D-Iran, and compare its red cell parameters and peak characteristics with those of Hb E that commonly elutes in the Hb A2 window.

Methods

Generally, we assess abnormal Hb using CE-HPLC as the primary technique along with alkaline and acid electrophoresis. All cases with Hb A2 window >9%, as assessed by CE-HPLCs during 2009–2013, were selected.

Results

Twenty-nine cases with Hb D-Iran variant were identified—25 heterozygous, 2 homozygous, 1 compound heterozygous Hb D-Iran/β-thalassemia, and 1 Hb D-Iran/Hb D-Punjab. Overall prevalence of Hb D-Iran was 0.23%. Compared to patients with Hb E, those with Hb D-Iran had significantly higher Hb (12.1 vs. 11.3 g/dL, P=0.03), MCV (82.4 vs. 76.4 fL, P=0.0044), MCH (27.9 vs. 25.45 pg, P =0.0006), and MCHC (33.9 vs. 33.3 g/dL, P=0.0005). Amount of abnormal Hb (40.7 vs. 26.4%, P=0.0001) was significantly higher while retention time (3.56 vs. 3.70 min, P=0.0001) was significantly lower in Hb D-Iran than in Hb E.

Conclusion

Hb D-Iran peak can be easily missed if area and retention time of the Hb A2 window are not carefully analyzed. To distinguish between variants, careful analysis of peak area and retention time is sufficient in most cases and may be further confirmed by the second technique—alkaline electrophoresis.

Molecular Epidemiology of Hemoglobinopathies in Cambodia

Determining the magnitude of the thalassemia problem in a country is important for implementing a national prevention and control program. In order to acquire accurate thalassemia prevalence data, the gene frequency of α- and β-thalassemia (α- and β-thal) in different regions of a country should be determined. The molecular basis of thalassemia in Cambodia was performed by polymerase chain reaction (PCR)-based techniques in a community-based cross-sectional survey of 1631 unrelated individuals from three regions, Battambang, Preah Vihear and Phnom Penh. Thalassemia mutations were detected in 62.7% of the three studied population of Cambodia. Hb E (HBB: c.79G > A) was the most common β-globin gene mutation with a frequency ranging from 0.139 to 0.331, while the most frequent α-globin gene mutation was the -α(3.7) (rightward) deletion (0.098-0.255). The other frequencies were 0.001-0.003 for β-thal, 0.008-0.011 for α-thal-1 (- -(SEA)), 0.003-0.008 for α-thal-2 [-α(4.2) (leftward deletion)], 0.021-0.044 for Hb Constant Spring (Hb CS, HBA2: c.427T > C) and 0.009-0.036 for Hb Paksé (HBA2: c.429A > T). A regional specific thalassemia gene frequency was observed. Preah Vihear had the highest prevalence of Hb E (55.9%), α-thal-2 (24.0%) and nondeletional α-thal (15.1%), whereas Phnom Penh had the lowest frequency of thalassemia genes. Interestingly, in Preah Vihear, the frequency of Hb Paksé was extremely high (0.036), almost equivalent to that of Hb CS (0.044). Our results indicate the importance of micromapping and epidemiology studies of thalassemia, which will assist in establishing the national prevention and control program in Cambodia.

Hemoglobin Constant Spring (Hb CS) Missed by HPLC in an Hb E Trait Pregnancy Resulting in Hb H-CS Disease in a Thai Girl: Utility of Capillary Electrophoresis

Hemoglobin Constant Spring [Hb CS; α142, Term→Gln (TAA>CAA IN α2)] is often missed by routine laboratory testing, especially in subjects with co-inheritance of β-thalassemia or β-variants. We reported the case of a 1-year-old female with Hb H-CS disease who was born from a father with heterozygous of α-thalassemia-1 Southeast Asian type deletion and a mother with the combination of Hb CS and Hb E [β26 (B8) Glu→Lys, GAG>AAG] trait. A very tiny peak of Hb CS of the mother was easily ignored on the high performance liquid chromatography chromatogram while it was clearly seen on the capillary electrophoresis (CE) electrophoregram. Therefore, the CE is useful in screening for heterozygous Hb CS in a person with Hb E trait. This is of potential benefit for prevention of new cases of Hb H-CS disease.

Detection of Hb Constant Spring (HBA2: c.427T>C) Heterozygotes in Combination with β-Thalassemia or Hb E Trait by Capillary Electrophoresis

Hb Constant Spring (Hb CS; HBA2: c.427T>C) is often missed by routine laboratory testing as its mRNA as well as gene product are unstable and presented at a low level in peripheral blood. This study aimed to analyze the efficacy of capillary electrophoresis (CE) for detecting and quantifying of Hb CS in β-thalassemia (β-thal) trait or Hb E (HBB: c.79G>A) trait samples with reduced β-globin chain expression. Thalassemia diagnostic data were reviewed in 2524 blood samples that were submitted to the laboratory of the Associated Medical Sciences Clinical Service Center, Chiang Mai, Thailand for hemoglobinopathy and thalassemia diagnosis. DNA analysis for Hb CS was performed in 322 β-thal trait and 397 Hb E trait samples using the amplification refractory mutation system (ARMS). The CE electropherogram of Hb CS at zone 2 was observed in all five samples with β-thal trait and nine samples with Hb E trait with levels varying from 0.1-2.8 and 0.1-2.3%, respectively. Thus, the CE method proved useful for screening of Hb CS in samples with β-thal trait or Hb E trait, which is essential for providing accurate diagnosis, genetic counseling, prevention and control programs of Hb H-CS disease.

The correlation of α-globin gene mutations and the XmnI polymorphism with clinical severity of Hb E/β-thalassemia

Clinical severity assessment and molecular analysis of β-, α-globin genes and the -158 (C > T) XmnI polymorphism of the (G)γ-globin gene were performed in 80 pediatric patients with Hb E (HBB: c.79G > A)/β-thalassemia (β-thal) to investigate the effects of coinheritance of α-thalassemia (α-thal) and other molecular determinants on their clinical severity. The mean age was 9.4 ± 5.1 years. By using clinical severity score, 35 (43.8%), 27 (33.8%) and 18 cases (22.5%) had moderate, mild and severe disease, respectively. Nine β-thal mutations were identified. All were β⁰ or severe β⁺ mutations. Five patients (6.3%) had coinherited α⁰-thal. All five patients had mild disease with baseline hemoglobin (Hb) values of 7.9 ± 1.5 g/dL, mild hepatosplenomegaly and close-to-normal growth. Only one required a red blood cell transfusion. The disease severity was significantly different among the groups with and without α-thal (p = 0.025), but was not different among the groups with or without the XmnI polymorphism (p = 0.071). This study demonstrates that coinheritance of α⁰-thal alleviates the degree of disease severity in Hb E/β-thal. All our patients with coinherited α⁰-thal have mild disease.

Blood transfusion from a Hb E trait donor can affect β-thalassemia diagnosis

A subject with Hb E (HBB: c.79G > A) trait is asymptomatic and can become a blood donor. However, a blood transfusion from a Hb E trait donor can affect β-thalassemia (β-thal) diagnosis. Blood samples from three Thai women were sent to the Associated Medical Sciences (AMS) Clinical Service Center, Chiang Mai, Thailand, for thalassemia diagnosis. Their Hb A2 levels, analyzed by high performance liquid chromatography (HPLC), were higher than 4.0%, thus they were diagnosed to have β-thal. However, elevated Hb A2 levels in these patients were not certain because the Hb A2 levels analyzed at the initial hospitalization and follow-up were controversial. In addition, there were some cases shown to have controversy between the increased Hb A2 level and red cell indices. The blood transfusion history was confirmed and hemoglobin (Hb) analysis was reanalyzed by capillary electrophoresis (CE). On the CE electrophoregram, Hb A2 levels were observed to be normal and Hb E peaks were present. Therefore, to rule out misdiagnosis and unnecessary genetic counseling, Hb analysis should be performed on the recipient prior to blood transfusions. Moreover, CE has a high efficiency to prevent the misinterpretation of Hb analysis in patients who receive blood transfusions from a donor carrying Hb E.

Hemoglobinopathies in South Gujarat population and incidence of anemia in them

OBJECTIVE:

To Screen of South Gujarat population for determination of prevalence of different hemoglobinopathies particularly beta thalassemia trait (BTT) and sickle cell trait (SCT) and find out the incidence of anemia in them.

MATERIAL AND METHODS:

The present study screened 32,857 samples of students from different school and colleges in South Gujarat. Blood samples were initially tested for solubility test and complete hemogram on hematology analyzer. Samples having MCV (≤78), MCH (≤28) and/or positive solubility test were investigated for Hb electrophoresis on cellulose acetate membrane (pH 8.6). Hb A₂ level ≥3.5% was considered as diagnostic for BTT. High performance liquid chromatography on Biorad Hb variant system was done on samples having doubtful results.

RESULT:

Overall prevalence of BTT and SCT in South Gujarat was 4.4% and 1.3% respectively. Gamit, Vasava, Chaudhary, and Mahyavanshi castes had high prevalence of BTT (15.9%, 13.6%, 12.6%, and 6.9%) as well as SCT (22.2%, 15.2, 22.3, and 4.2%) respectively. Other communities like Lohana (10.8%), Sindhi (10.2%), Prajapati (6.3%), and Ghanchi (6.2%) also showed higher prevalence of BTT. Incidence of mild to moderate anemia was higher in BTT and SCT compared to non-BTT or non-SCT subjects.

CONCLUSION

Study suggests that BTT is the most prevalent hemoglobinopathy in South Gujarat. β-thalassemia and Sickle cell anemia are highly prevalent in Mahyavanshi, Chaudhary, Gamit, Vasava and Rohit. Prajapati, Lohana, Leva Patel, and Ghanchi have β- thalassemia risk. SCT is more frequently detected in Dhodia Patel and Kukanas.