Rapid and accurate quantitation of Hb Bart's and Hb H using weak cation exchange high performance liquid chromatography: correlation with the alpha-thalassemia genotype

Hb Souli, a 6 bp in-frame deletion on the HBA2 gene (HBA2: c.[41-46delCCTGGG]) leads to α-thalassemia intermedia, when in trans to a single α-globin gene deletion

We report the case of a 5-year-old child with clinical and hematological findings consistent with the diagnosis of α-thalassemia intermedia (α-TI). Molecular analysis disclosed the common 3.7 kb deletion in the α-globin gene cluster in trans to a novel in-frame 6 bp deletion in the HBA2 gene. It removes the sequence CCTGGG (or GCCTGG) that normally encodes for alanine (codon 13) and tryptophan (codon 14). Even though several hemoglobin (Hb) variants with mutations affecting codons 13 or 14 have been described, Hb Souli (HBA2: c.[41-46delCCTGGG]) is, to the best of our knowledge, the first variant to be reported where both amino acid residues, α13Ala and α14Trp, are deleted, leading to unstable and rapidly degraded α-globin chains.

Strategies for basic laboratory diagnostics of the hemoglobinopathies in multi-ethnic societies: interpretation of results and pitfalls

The consistent multi-ethnic migrations of the last decades have considerably changed the epidemiology of the hemoglobinopathies. Healthy carriers of these conditions are present today in many nonendemic parts of the world, and severely affected children are now born where these diseases were previously rare or unknown. Improving the competence in carrier diagnostics at the laboratory level is one of the first concerns when introducing management and primary prevention of the severe conditions in nonendemic areas. This review describes how and when carriers should be correctly diagnosed and informed. The essential technologies needed for basic carrier diagnostics in different situations are summarized in some detail, and interpretation of the results and a number of related problems are discussed. The role of the hematology laboratory is essential, particularly in nonendemic areas where the first line of health care is often insufficiently aware of hemoglobinopathy management. Carriers living in nonendemic areas can be appropriately diagnosed and informed regarding genetic risk and prevention by well-organized laboratories. Both basic and specialized diagnostics are needed for the correct treatment for the anemic carriers, for primary prevention in couples at risk and for state-of-the art care of severely affected patients.

First Description in Tunisia of a Point Mutation at Codon 119 (CCT→TCT) in the α1-Globin Gene: Hb Groene Hart in Association with the − α3.7Deletion

Herein we describe the case of a Tunisian girl who presented with 3% Hb Bart's (gamma4) at birth. At the age of 3 years, she showed microcytosis and hypochromia in the absence of iron deficiency. The first step of molecular analysis was to test for the common Mediterranean mutations and the classical -alpha3.7 deletion was found in the heterozygous state. Since this finding could not explain the level of Hb Bart's at birth, or the hypochromia and microcytosis, all the alpha-globin genes were sequenced. This revealed a rare point mutation at codon 119 (CCT-->TCT) in the alpha1-globin gene, identified for the first time in Tunisia, and which has previously been described as an unstable hemoglobin (Hb) variant named Hb Groene Hart [alpha119(H2)Pro-->Ser (alpha1)]. Here the -alpha3.7/alpha(alpha)119(CCT-->TCT) genotype is responsible for the alpha-thalassemia (thal) trait phenotype.

Hb Southern Italy: coexistence of two missence mutations (the Hb Sun Prairie alpha2 130 Ala --> Pro and Hb Caserta alpha2 26 Ala --> Thr) in a single HBA2 gene

This study describes a new molecular condition in the alpha(2)-globin gene (HBA2) found in six unrelated families from Southern Italy (Campania and Sicily). This new double mutant form of haemoglobin is called Hb Southern Italy and originated from the coexistence of two known mutations occurring in the same globin gene, HBA2 26 G-->A (Hb Caserta) and HBA2 130 G-->C (Hb Sun Prairie). Hb Sun Prairie was originally observed in Indian patients in either the homozygous state, with severe hemolytic anemia, and in the heterozygous state with microcytosis, or in asymptomatic cases as an alpha-thalassemia carrier phenotype. Hb Caserta was observed for the first time in a Casertian family (South Italy) that displayed a slowmigrating haemoglobin upon investigation. We report the clinical phenotype and molecular study of this new double mutant form of haemoglobin in heterozygous and homozygous subjects, as well as in association with alpha degrees delectional thalassemia.

Preparation of highly efficient monolithic silica capillary columns for the separations in weak cation-exchange and HILIC modes

Weak cation-exchange (WCX) and HILIC modes columns were prepared by on-column polymerization of acrylic acid on monolithic silica capillary columns modified with N-(3-triethoxysilylpropyl)methacrylamide anchor groups. The polymer-coated columns could be used for HILIC mode separation of pyridylamino (PA)-sugars and peptides including a tryptic digest of BSA, while for weak cation-exchange mode for the separation of proteins and nucleosides even at high linear velocity. The poly(acrylic acid) coated monolithic silica capillary columns showed greater retention toward PA-sugars than a polyacrylamide coated monolithic silica capillary columns prepared in the same manner. Proteins and nucleosides were separated effectively at pH 6.9 using the same column. The column provided fair permeability after the polymer-coating step. High-speed separation of proteins at u=4.66 mm/s with high efficiency was shown to be possible, while high-speed separation of nucleosides has achieved within one minute using the column at u=8.67 mm/s, suggesting that the column will be suitable for the second dimension separation of multidimensional HPLC systems.

Anemia and hydrops in a fetus with homozygous hemoglobin constant spring

Hemoglobin Constant Spring (Hb CS) is an unstable hemoglobin (Hb) variant that results from a nucleotide substitution at the termination codon of the alpha2-globin gene. The compound heterozygosity of alpha-thalassemia and Hb CS (--/alphaCSalpha) results in a Hb H/CS disease which is clinically more severe than deletional Hb H disease. Homozygosity of Hb CS (alphaCSalpha/alphaCSalpha) is generally characterized with mild hemolytic anemia, jaundice, and splenomegaly. The authors report 1 case with Hb CS homozygosity who presented with fetal anemia and hydrops. Intrauterine transfusions were given which rendered a favorable outcome. This report demonstrates an unusual and serious in utero complication in a fetus with Hb CS/CS.

Chicken Egg Yolk Antibodies Specific for the γ Chain of Human Hemoglobin for Diagnosis of Thalassemia

Immunoglobulin Y (IgY) technology was used to generate anti-hemoglobin Bart's (Hb Bart's) IgY antibodies (Abs) for development into an enzyme-linked immunosorbent assay (ELISA) test for thalassemia diagnosis. Hb Bart's purified from the hemolysate of a patient with Hb Bart's hydrops fetalis (homozygous alpha-thalassemia) was used to immunize a chicken via the pectoralis muscle. After water dilution and sodium sulfate precipitation, 40 to 70 mg of IgY could be extracted from an egg. IgY, first detected in sera 2 weeks after immunization, reached the highest titer at week 4, and the titer remained stable for at least 2 weeks before declining. The pattern of Ab response in the yolk was the same as in the serum but was somewhat delayed. The IgY Abs produced reacted with gamma globin, Hb Bart's, Hb F, normal cord hemolysate (Hbs F plus A), and Hb Bart's hydrops fetalis (Hbs Bart's plus Portland) and to a lesser degree with beta globin, Hb A, Hb A2 and adult hemolysate (Hbs A plus A2), but the Abs did not react with alpha globin. Immunoaffinity purification with Hb A coupled to Sepharose was used to isolate an unbound IgY that reacted with Hb F, Hb Bart's, and gamma globin, and this IgY was used to develop an ELISA test for thalassemia diagnosis. The results of direct ELISA analyses of 336 hemolysate samples from individuals with various known thalassemia genotypes and phenotypes and from healthy individuals confirmed the specificity of the polyclonal Abs for Hbs containing Hb F and Hb Bart's. This specificity, which was due to the Abs' strong reactivity in cases of pathologic thalassemic diseases and weak reactivity in cases of nonpathologic thalassemic diseases, depended on the levels of Hb Bart's and Hb F.

Molecular and hematological profiles of hemoglobin EE disease with different forms of α-thalassemia

We describe hematologic and DNA characterization of hemoglobin (Hb) E homozygote with various forms of alpha-thalassemia in Thai individuals. Altogether, 131 unrelated adult subjects with Hb EE at routine Hb analysis were studied. Forty-two cases were found to carry alpha-thalassemia with ten different genotypes. These included 21 cases with alpha(+)-thalassemia heterozygote (-alpha(3.7)/alphaalpha), one case with alpha(+)-thalassemia heterozygote (-alpha(4.2)/alphaalpha), six cases with Hb Constant Spring heterozygote (alpha(CS)alpha/alphaalpha), four cases with homozygous alpha(+)-thalassemia (-alpha(3.7)/-alpha(3.7)), one case with homozygous alpha(+)-thalassemia (-alpha(4.2)/-alpha(4.2)), two cases with compound alpha(+)-thalassemia/Hb Constant Spring (-alpha(3.7)/alpha(CS)alpha), one case with compound alpha(+)-thalassemia/Hb Paksé (-alpha(3.7)/alpha(PS)alpha), four cases with alpha(0)-thalassemia heterozygote (--(SEA)/alphaalpha), and, unexpectedly, two cases with compound alpha(0)-thalassemia/alpha(+)-thalassemia [(--(SEA)/-alpha(3.7)) and (--(SEA)/-alpha(4.2))]. The hematological expression of these Hb E homozygotes with various forms of alpha-thalassemia was presented comparatively with those of the 89 cases of pure Hb E homozygotes. Overlapping levels of Hb E, Hb F, and other hematological parameters were observed which did not predict clinical severity, indicating a need for alpha-globin gene analysis for accurate diagnosis and improved genetic counseling.

Distinct phenotypic expression associated with a new hyperunstable alpha globin variant (Hb heraklion, alpha1cd37(C2)Pro>0): comparison to other alpha-thalassemic hemoglobinopathies

Clinical phenotypes associated with abnormal globin chain biosynthesis may result in thalassemia (deficient quantity) or hemolytic anemia (abnormal hemoglobins). However, the phenotypic expression of hyperunstable hemoglobin variants often includes features of thalassemia, along with variable peripheral hemolysis. Hemoglobinopathies caused by highly unstable beta-chain variants have a dominant thalassemia-like phenotype, in which carriers have a clinical expression of thalassemia intermedia, but highly unstable alpha-globin variants are usually only phenotypically apparent when they interact with other alpha-thalassemia mutations. In a child with clinical and hematological features consistent with beta-thalassemia intermedia, DNA analysis excluded any beta-globin gene mutations but characterized a novel deletion cd37(C2)Pro>0 (Hb Heraklion) in the alpha1 globin gene, in trans to a common Mediterranean nondeletion alpha-thalassemia mutation (alpha(Hph)alpha). The deletion of proline at alpha37(C2) is predicted to result in severe instability of the variant hemoglobin, which on interaction with a synthesis-deficient alpha-thalassemia mutation causes a relatively severe dyserythropoietic anemia, representing an alternative phenotype associated with highly unstable alpha-chain variants. Hb Heraklion is the fourth highly unstable alpha-globin variant that we have observed in patients from Greece and Albania. Two variants involve the alpha2-globin gene: Hb Agrinio (alpha29(B10)Leu>Pro) and Hb Adana (alpha59(E8)Gly>Asp), and two the alpha1-gene: Hb Aghia Sophia (alpha62(E11)Val>0) and (Hb Heraklion a37(C2)Pro>0). Each has been observed on interaction with a different alpha-thalassemia mutation and the phenotypes associated with these highly unstable alpha-variants are presented.