Molecular characterization of Hb D-Punjab [beta121(GH4)Glu-->Gln] in Thailand

Rare Association of Hb D-Los Angeles (HBB: c.364G>C) with Hb H Disease: Diagnosis and Clinical Implications

Hb D-Los Angeles (or Hb D-Punjab) (HBB: c.364G > C) is found worldwide and is derived from a point mutation in the β-globin gene prevalent in the Punjab region of Northwestern India. Heterozygous or homozygous inheritance does not cause significant medical problems, whereas association with other hemoglobinopathies, especially β-thalassemia (β-thal) and sickle cell disease, changes the phenotype. Coinheritance of Hb D-Los Angeles with Hb H disease (α-/- -) has never been reported before. The presence of this rare combination in a family of Greek origin is herein described, and the challenges involving clinical management are discussed.

Time estimations by network of beta globin gene cluster haplotypes linked with Hb D-Los Angeles [β121 (GH4) Glu → Gln GAA → CAA] mutation in the world populations

Background

β‐Globin gene cluster haplotypes associated with the Hb D‐Los Angeles mutation have been reported in many different locations in different populations including Italy, Iran, Thailand, Belgium, Mexico, Holland, and Turkey. In this study, we have identified genetic relationships and formation periods between the haplotypes reported in the world regarding the Hb D‐Los Angeles.

Methods

We comparatively analyzed the RFLP (restriction fragment length polymorphism) data in Denizli region and world populations using Arlequin 3.5 statistical software program. The data obtained from the Arlequin software were then entered into the Phylogenetic Network software to calculate the age estimates and to discover possible links between the haplotypes.

Results

We observed the frequencies of the β‐globin gene haplotypes for the seven polymorphic restriction sites around the world and calculated the estimated time of haplotypes using Network software on the basis of ancestral haplotypes. We performed the phylogenetic network analysis of the haplotypes linked with Hb D‐Los Angeles mutation by processing the data of frequency and age estimations with Network software.

Conclusion

Our period of time results suggests that HAP1 was formed before modern human migration to Asia and/or independent origin of the Hb D‐Los Angeles mutation from other populations. Considering that the population in Denizli region started the Hb D‐Los Angeles mutation past about 40,000 years ago, it can be said that HAP1, HAP15, and HAP21 belong to the gene pool with an external effect. Our period of time results of HAP6 is compatible with published dating results.

Diagnosis of Compound Heterozygous Hb Tak/β-Thalassemia and HbD-Punjab/β-Thalassemia by HbA2 Levels on Capillary Electrophoresis

A misdiagnosis of β-thalassemia carrier in samples with Hb Tak and HbD-Punjab, the β-variants, can be a cause of inappropriate genetic counseling thus having a new case of β-thalassemia major. A capillary electrophoresis (CE) is very efficient in separating and quantifying HbA₂. In this study, HbA₂ levels of samples which were doubted for compound heterozygous Hb Tak/β-thalassemia or heterozygous HbD-Punjab/β-thalassemia were measured and compared between CE and high performance liquid chromatography (HPLC). The molecular confirmation for Hb Tak, HbD-Punjab and β-thalassemia codons 17 (A > T), 41/42 (-TCTT), 71/72 (+A) and IVSI-nt1 (G > T) mutations and 3.4 kb deletion were also performed. Based on DNA analysis, 3 cases were diagnosed as compound heterozygous Hb Tak/β-thalassemia and one for HbD-Punjab/β-thalassemia. The elevated HbA₂ levels were found in all 4 samples with rages of 4.6-7.3% on CE while those were not found on HPLC. Thus, the elevated HbA₂ measured by CE can be used as a screening parameter for differentiating the homozygote of Hb Tak and HbD-Punjab from the compound heterozygote of these hemoglobinopathies and β-thalassemia.

Coinheritance of hemoglobin D-Punjab and β0-thalassemia 3.4 kb deletion in a Thai girl

Hemoglobin (Hb) D. Punjab [β121(GH4) Glu→Gln; HBB: C.364G>C] and β⁰-thalassemia 3.4 kb deletion are very rare in the Thai population. For the first time, the coinheritance of HbD-Punjab with β⁰-thalassemia 3.4 kb deletion was reported in a 7-year-old Thai girl. She had mild anemia (Hb 115.0 g/L and mean corpuscular hemoglobin 18.1 pg) with red blood cell microcytosis (mean corpuscular volume 52.5 fL). By capillary electrophoresis (CE), HbD-Punjab was found at a migration position of 180 s with the value of 81.9% while the level of HbA₂ was 7.3%. Based on the elevated HbA₂, the molecular analysis for detection of β⁰-thalassemia mutations was performed. The 490 bp amplified fragments from β⁰-thalassemia 3.4 kb deletion was observed. Thus, the coinheritance of HbD-Punjab with β⁰-thalassemia can be found in the Thai population. The HbA₂ measured on CE is a reliable parameter for differentiating the homozygote of HbD-Punjab and compound heterozygote of HbD-Punjab and β⁰-thalassemia.

Clinical, hematological and genetic data of a cohort of children with hemoglobin SD

Introduction

The hemoglobin FSD is very uncommon in newborn screening programs for sickle cell disease. In the program of Minas Gerais, Brazil, the clinical course of children with hemoglobin SD was observed to be heterogeneous. The objective of this study was to estimate the incidence (1999–2012) and to describe the natural history of a cohort of newborns with hemoglobin SD.

Methods

Isoelectric focusing was the primary method used in newborn screening. Polymerase chain reaction-restriction fragment length polymorphism and gene sequencing were used to identify mutant alleles and for haplotyping. Gap-polymerase chain reaction was used to detect alpha-thalassemia.

Results

Eleven cases of hemoglobin S/D-Punjab and eight of Hb S-Korle Bu were detected. Other variants with hemoglobin D mobility were not identified. All hemoglobin D-Punjab and hemoglobin Korle Bu alleles were associated with haplotype I. Among the children with hemoglobin S/D-Punjab, there were four with the β^S CAR haplotype, six with the Benin haplotype, and one atypical. Results of laboratory tests for hemoglobin S/D-Punjab and hemoglobin S-Korle Bu were: hemoglobin 8.0 and 12.3 g/dL (p-value <0.001), leukocyte count 13.9 × 10⁹/L and 10.5 × 10⁹/L (p-value = 0.003), reticulocytes 7.5% and 1.0% (p-value <0.001), hemoglobin F concentration 16.1% and 6.9% (p-value = 0.001) and oxygen saturation 91.9% and 97% (p-value = 0.002), respectively. Only hemoglobin S/D-Punjab children had acute pain crises and needed blood transfusions or hydroxyurea. Those with the Benin β^S haplotype had higher total hemoglobin and hemoglobin F concentrations compared to the CAR haplotype. Transcranial Doppler was normal in all children.

Conclusion

The clinical course and blood cell counts of children with hemoglobin S/D-Punjab were very similar to those of hemoglobin SS children. In contrast, children with hemoglobin S-Korle Bu had clinical course and blood cell counts like children with the sickle cell trait.

Hemoglobin D-Punjab: origin, distribution and laboratory diagnosis

This review discusses hemoglobin D-Punjab, also known as hemoglobin D-Los Angeles, one of the most common hemoglobin variants worldwide. It is derived from a point mutation in the beta-globin gene (HBB: c.364G>C; rs33946267) prevalent in the Punjab region, Northwestern Indian. Hemoglobin D-Punjab can be inherited in heterozygosis with hemoglobin A causing no clinical or hematological alterations, or in homozygosis, the rarest form of inheritance, a condition that is commonly not related to clinical symptomatology. Moreover, this variant can exist in association with other hemoglobinopathies, such as thalassemias; the most noticeable clinical alterations occur when hemoglobin D-Punjab is associated to hemoglobin S. The clinical manifestations of this association can be similar to homozygosis for hemoglobin S. Although hemoglobin D-Punjab is a common variant globally with clinical importance especially in cases of double heterozygosis, hemoglobin S/D-Punjab is still understudied. In Brazil, for example, hemoglobin D-Punjab is the third most common hemoglobin variant. Thus, this paper summarizes information about the origin, geographic distribution, characterization and occurrence of hemoglobin D-Punjab haplotypes to try to improve our knowledge of this variant. Moreover, a list of the main techniques used in its identification is provided emphasizing the importance of complementary molecular analysis for accurate diagnosis.

γA Gene Repeats Polymorphism for the Analysis of Haplotypes of Abnormal Hemoglobins

Aim of this study was to analyze γ A gene repeat polymorphism for the analysis of haplotypes of hemoglobin (Hb) variants such as Hb S, Hb D-Punjab, Hb O-Arab. Sickle cell cases had mainly Benin and Arab/Indian haplotype. We found three different haplotypes among Hb S, Hb O Arab and Hb D-Punjab cases. We named these three variants as Anatolian-1 and Anatolian-2 and Asian. Our data revealed that Hb O Arab may arise twice one from Asia and the other from Europe.

A large cohort of hemoglobin variants in Thailand: molecular epidemiological study and diagnostic consideration

Background

Hemoglobin (Hb) variants are structurally inherited changes of globin chains. Accurate diagnoses of these variants are important for planning of appropriate management and genetic counseling. Since no epidemiological study has been conducted before, we have investigated frequencies, molecular and hematological features of Hb variants found in a large cohort of Thai subjects.

Materials and Methods

Study was conducted on 26,013 unrelated subjects, inhabiting in all geographical parts of Thailand over a period of 11 years from January 2002-December 2012. Hb analysis was done on high performance liquid chromatography (HPLC) or capillary electrophoresis (CE). Mutations causing Hb variants were identified using PCR and related techniques.

Results

Among 26,013 subjects investigated, 636 (2.4%) were found to carry Hb variants. Of these 636 subjects, 142 (22.4%) carried α-chain variants with 13 different mutations. The remaining included 451 (70.9%) cases with 16 β-chain variants, 37 (5.8%) cases with Hb Lepore (δβ-hybrid Hb) and 6 (0.9%) cases with a single δ-chain variant. The most common α-globin chain variant was the Hb Q-Thailand (α^{74GAC-CAC, Asp-His}) which was found in 101 cases (15.8%). For β-globin chain variants, Hb Hope (β^{136GGT-GAT, Gly-Asp}) and Hb Tak (β^{146+AC, Ter-Thr}) are the two most common ones, found in 121 (19.0%) and 90 (14.2%) cases, respectively. Seven Hb variants have never been found in Thai population. Hb analysis profiles on HPLC or CE of these variants were illustrated to guide presumptive diagnostics.

Conclusions

Hb variants are common and heterogeneous in Thai population. With varieties of thalassemias and hemoglobinopathies in the population, interactions between them leading to complex syndromes are common and render their diagnoses difficult in routine practices. Knowledge of the spectrum, molecular basis, genotype-phenotype correlation and diagnostic features should prove useful for prevention and control of the diseases in the region.

Allele frequency of VNTR locus D1S80 observed in Hb D-Los Angeles carrires

One of our previous studies presented the allele frequencies of D1S80 VNTR locus in province Denizli including the high frequencies of allele 24 and 18. In Denizli province of Turkey, the most common abnormal variant is Hb D-Los Angeles with a frequency of 57.8 % of the total abnormal Hbs. The aim of this study is to identify the allele frequencies of D1S80 VNTR locus in Hb D-Los Angeles carriers in Denizli province of Turkey. We studied unrelated 36 Hb D-Los Angeles carriers residing in Denizli province of Turkey. The size range of the D1S80 VNTR locus PCR products was determined first by agarose gel electrophoresis and then by a capillary electrophoresis system. For all subjects, DNA sequencing was performed. Allele frequency, theta (k) value, and observed and expected heterozygosity were calculated using Arlequin Software version 3.11. The most common alleles were the 24 (32 %), 18 (18.1 %) and 29 (16.7 %) alleles, and frequencies of these alleles were 0.329, 0.186 and 0.171 respectively. Other observed alleles percentages were 33, 2 %. We did not observe alleles 6, 15, 27 and 35, but we observed alleles 20 and 33. Results were in Hardy-Weinberg linkage disequilibrium. Observed heterozygosity was 0.889, and expected heterozygosity was 0.847. Theta (k) value was 4.91 (95 % confidence interval limits). According to our results, we concluded that Hb D-Los Angeles carriers have different allele frequencies in D1S80 VNTR and also have their own D1S80 VNTR locus divergence.

Molecular characterization of hemoglobin D Punjab traits and clinical-hematological profile of the patients

CONTEXT AND OBJECTIVE

Hemoglobin (Hb) D hemoglobinopathies are widespread diseases in northwestern India and usually present with mild hemolytic anemia and mild to moderate splenomegaly. The heterozygous form of Hb D is clinically silent, but coinheritance of Hb D with Hb S or beta-thalassemia produces clinically significant conditions like thalassemia intermedia of moderate severity. Under heterozygous conditions with coinheritance of alpha and beta-thalassemia, patients show a degree of clinical variability. Thus, our aim was to molecularly characterize the Hb D trait among individuals who were clinically symptomatic because of co-inheritance of alpha deletions or any beta-globin gene mutations.

DESIGN AND SETTING

This was a cross-sectional study conducted in an autonomous tertiary-care hospital.

METHODS

Complete blood count and red cell indices were measured using an automated cell analyzer. Quantitative assessment of hemoglobin Hb F, Hb A, Hb A2 and Hb D was performed by means of high performance liquid chromatography (HPLC). DNA extraction was done using the phenol-chloroform method. Molecular analyses on common alpha deletions and common beta mutations were done using the Gap polymerase chain reaction and Amplification Refractory Mutation System, respectively.

RESULTS

We evaluated 30 patients and found clinical variation in the behavior of Hb D traits. In six patients, the Hb D traits were clinically symptomatic and behaved like those of thalassemia intermedia. Molecular characterization showed that three out of these six were IVS-1-5 positive.

CONCLUSIONS

HPLC may not be the gold standard for diagnosing symptomatic Hb D Punjab traits. Hence, standard confirmation should include molecular studies.

β-globin gene haplotypes linked with the Hb D-Punjab [β121(GH4)Glu→Gln, GAA>CAA] mutation in eastern India

Hb D-Punjab [β121(GH4)Glu→Gln] is prevalent in the northern states of the Indian subcontinent. Due to inadequate data from Asian countries, the origin and spread of the Hb D-Punjab mutation are uncertain. In a study of sickle cell hemoglobinopathies, we detected the Hb D-Punjab mutation in 25 subjects from 11 unrelated Agharia families. Twelve cases were Hb S [β6(A3)Glu→Val]/Hb D-Punjab compound heterozygotes and 13 were Hb D trait carriers. In 76.0% of the cases, the β(D) gene was linked to haplotype I, whereas 24.0% had a novel haplotype. None of the haplotypes matched the β(A) haplotype of the local population. In view of the ancestral origin of the subjects and the high prevalence of the β(D) gene in the states of northern India, we suggest a North Indian origin for the β(D) mutation in our population. The finding of a novel haplotype in eastern India supports the hypothesis of a multicentric origin of this mutation.

Hemoglobin D-Punjab syndromes in India: a single center experience on cation-exchange high performance liquid chromatography

BACKGROUND

Hemoglobin-D-Punjab (HbDP) is an uncommon structural hemoglobin variant, which is reported to be prevalent in North Western India. There are only a few small series, family studies and anecdotal reports of this entity in the literature. We report the largest single center experience on this entity diagnosed by cation-exchange high performance liquid chromatography (CE-HPLC) from India.

AIM

To document and analyze the clinical, hematological and chromatographic parameters of patients with HbDP syndromes.

PATIENTS AND METHODS

A total of 6889 blood samples (both pediatric and adult) were screened for hemoglobinopathies and structural hemoglobin variants by CE-HPLC; beta thal short program (BTS), Bio-Rad variant for evaluation of anemia and for family and antenatal screening studies.

RESULTS AND CONCLUSION

A total of 484 cases of structural hemoglobin variants comprising of HbS, E, D-Punjab, D Iran, Lepore, and J-Meerut were detected. HbDP syndromes constituted 38 (7.8%) of all hemoglobin variants and 0.55% of all the samples screened for hemoglobinopathies. Heterozygous HbDP constituted 23 of 38 (61%) cases and homozygous HbD/D, HbS/D and HbD/beta constituted 9/38 (24%), 2/38 (5%), and 4/38 (10%) respectively. HbDP syndromes are not uncommon and are relatively underdiagnosed. CE-HPLC has the advantage of rapid detection and accurate quantitation. Electrophoresis and CE-HPLC can be complementary in making accurate diagnosis of these entities.

Genetic Origin of Hb D-Los Angeles [β121(GH4)Glu→Gln,GAA→CAA] According to the β-Globin Gene Cluster Haplotypes

Hb D-Los Angeles (also known as D-Punjab, D-North Carolina, D-Portugal, D-Chicago and Oak Ridge) is an abnormal hemoglobin (Hb) with an amino acid substitution of glutamine for glutamic acid at codon 121 of the beta-globin gene. The origin and spread of Hb D-Los Angeles is not known. This is due to lack of information and remains to be elucidated. According to published reports, the Hb D-Los Angeles mutation is mostly linked with Mediterranean haplotype I [+ - - - - + +]. Besides the Mediterranean haplotype, a novel haplotype was also reported from Thailand [- - + + - - + + +]. Here we report a new haplotype from Turkey [- + -- + + +] that has not been described before. These results suggest that the Hb D-Los Angeles mutation has at least three different genetic origins.

The beta-globin gene haplotypes associated with Hb D-Los Angeles [beta121(GH4)Glu --> Gln] in Western Iran

Hb D-Los Angeles is characterized by the substitution of glutamine for glutamic acid at position 121 of the beta-globin chain. The present investigation is the first study on the beta-globin gene haplotypes associated with beta-D-Los Angeles in Western Iran. Thirty two individuals from 11 unrelated families from Western Iran were studied. The Hb D-Los Angeles status of all cases was confirmed using polymerase chain reaction (PCR) followed by digestion with EcoRl. The haplotype of the beta-globin gene cluster was determined by a PCR-RFLP (restriction fragment length polymorphism) procedure. The haplotype background of the betaA chromosomes was also determined in 35 normal subjects from the same geographic region. The beta-globin gene haplotype analysis demonstrated that all beta-D-Los Angeles genes (23 genes) were in linkage disequilibrium with haplotype I [+----++]. Among the 70 betaA chromosomes, 30 chromosomes (42.9%) were associated with haplotype I. The present study indicates the unicentric origin of the beta-D-Los Angeles gene in Western Iran. It seems that this mutation may have occurred at the same chromosomal background common in the local population.

Association of Hb Q-Thailand with homozygous Hb E and heterozygous Hb Constant Spring in pregnancy

Hemoglobin (Hb) Q-Thailand [alpha74(EF3): Asp-->His] is an abnormal Hb found mainly in China and South-east Asian countries. Association of the alpha(Q-Thailand) allele with alpha-thalassemia has important implications in diagnosis. We report the hitherto undescribed conditions of this variant in two unrelated pregnant Thai women. Routine Hb analyses using high-performance liquid chromatography identified abnormal Hb migrating after Hb A(2) in addition to a homozygous Hb E in the proband 1 and to a heterozygous Hb Constant Spring (Hb CS) in the proband 2. Further alpha-globin gene analysis identified that the variant was caused by the GAC to CAC mutation at codon 74 of the alpha1-globin gene corresponding to the Hb Q-Thailand, detected in cis to the 4.2 kb deletional alpha-thalassemia 2 in both cases. Interaction of the alpha(Q-Thailand) with the beta(E) globin chains in the proband 1 leads to a Hb variant, namely the Hb QE. Family study of the proband 1 showed that her non-pregnant sister had the same genotype but her father was a double heterozygote for Hb E and Hb Q-Thailand in whom both Hb Q-Thailand and Hb QE were detected. Genotype-phenotype relationships observed in these families with complex hemoglobinopathies are presented and compared with those of simple homozygote for Hb E, heterozygote for Hb CS and heterozygote for Hb Q-Thailand found in other unrelated subjects. A simple DNA assay based on allele-specific polymerase chain reaction for simultaneous detection of the Hb Q-Thailand mutation and the 4.2 kb deletional alpha-thalassemia 2 determinant was developed and validated.

Multiplex allele-specific PCR assay for differential diagnosis of Hb S, Hb D-Punjab and Hb Tak

BACKGROUND

Apart from hemoglobin (Hb) E, Hb D-Punjab [beta121(GH4)Glu-Gln] and Hb Tak [beta147Term-Thr] are the two most common beta-chain variants among the Asian population. These two Hb variants have similar alkaline electrophoretic mobilities and HPLC profiles as those of the Hb S [beta6(A3)Glu-Val]. Differential diagnosis of these clinically relevant hemoglobinopathies is therefore problematic. Direct detection of the beta-globin gene mutations would be another diagnostic alternative.

METHODS

A simultaneous DNA diagnosis of the three Hb variants was developed based on the multiplex allele-specific polymerase chain reaction (PCR) approach. The method was validated on 10 carriers of Hb D-Punjab, 5 carriers of Hb Tak, 2 carriers of Hb S and 50 normal individuals of Thai origin.

RESULTS

The three abnormal Hbs could be correctly diagnosed with the simultaneous PCR approach, and a complete concordance with results using other established methods was obtained.

CONCLUSIONS

The multiplex allele-specific PCR approach developed should prove useful in complementing routine Hb analysis for differential diagnosis of these three common Hb variants and should facilitate a program of hemoglobinopathy screening in the region.

Complex interaction of Hb Hekinan [alpha27(B8) Glu-Asp] and Hb E [beta26(B8) Glu-Lys] with a deletional alpha-thalassemia 1 in a Thai family

Hemoglobin (Hb) Hekinan (alpha27; Glu-Asp) is a rare alpha-chain variant found mainly in Japanese and Chinese whereas Hb E (beta26; Glu-Lys) is common among Southeast Asians. We report a hitherto undescribed condition in which these two variants co-segregate. The proband was a 25-yr-old Thai woman who was encountered with the presence of mild hypochromic microcytosis with Hb 8.2 g/dL, hematocrit (Hct) 26.0%, Mean Corpuscular Value (MCV) 68.6 fL, Mean Corpuscular Hemoglobin (MCH) 21.6 pg and Mean Corpuscular Hemoglobin Concentration (MCHC) 31.5 g/dL. Although Hb electrophoresis at alkaline pH did not show any abnormal band except Hb E in addition to Hb A, high performance liquid chromatography analysis revealed abnormal peaks at the Hb A and Hb E positions. DNA analysis of the proband revealed a GAG-GAT mutation at codon 27 of the minor alpha1-globin gene for Hb Hekinan in trans to the South-east Asian (SEA) deletional alpha-thalassemia 1 determinant and a GAG-AAG mutation at codon 26 of the beta-globin gene for Hb E. She was therefore a triple heterozygote for these three anomalies. Family study identified that her mother was a double heterozygote for Hb Hekinan and Hb E without alpha-thalassemia whereas her father was a classical Hb H disease patient. The genotype-phenotype relationship observed in this Thai family with complex hemoglobinopathies is presented and a simple DNA assay based on the polymerase chain reaction methodology for rapid diagnosis of Hb Hekinan is described.