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During a second pilot study, intended to explore the possibility of a country wide implementation of carrier diagnostics for hemoglobinopathies in The Netherlands, we observed a new abnormal hemoglobin (Hb) variant in three members of a family of Scandinavian origin living in the Dutch city of The Hague (Den Haag). The proband, a 34-year-old female presented with low Hb, packed cell volume (PCV) and red blood cell (RBC) values but was normocytic and normochromic. High performance liquid chromatography (HPLC) analysis revealed a partially separated fraction following Hb A. Molecular diagnostics disclosed a TTT>TAT transversion at HBB:c.137 causing a Phe-->Tyr single amino acid substitution at position 45 of the beta-globin gene. Previously described heterozygous mutations at the same position [Hb Cheverly (Phe-->Ser) and Hb Arta (Phe-->Cys)] were reported to be associated with mild chronic hemolysis similar to this case. We describe the hematological features of the six family members, the biochemical and molecular data and we discuss the possible consequences in combination with the common beta-thalassemia (beta-thal) trait.

We report two new abnormal hemoglobins (Hbs) caused by mutations on the α2 gene. One resulted into an Asn→His substitution at position 68, the other in a Leu→Gln substitution at position 125. The first mutation was observed in a 61-year-old North European Belgian male during Hb A(1c) analysis and subsequently in other members of his family. The variant was expressed at a normal level and caused no hematological abnormalities in the carriers. The second was found in a 27-year-old Turkish male living in The Hague, The Netherlands, who presented with microcytic hypochromic parameters without iron deficiency and was also carrier of the common α2 IVS-I (-5 nt) deletion.

The Lepore hemoglobins (Hbs) are a group of structural defects resulting from different recombination events between the delta- and beta-globin genes. They may come with different beta-thalassemia (beta-thal) minor-like phenotypes in the carrier and with variably severe phenotypes in the rare homozygote, and in the common compound heterozygote with beta-thal. The most seriously affected patients are those of Yugoslavian origin presenting with severe transfusion-dependent hemolytic anemia, dyserythropoiesis, hepatosplenomegaly and skeletal malformations. Because of genetic risk, couples where both partners are carriers of these combinations may require prognosis and prenatal diagnosis. In these cases, recognition of the defect must be done with particular care. We report a case of Hb Lepore induced by a yet unknown crossover event found in a 24-year-old Turkish male and compare the novel mutation with those previously reported.

We report a semi dominant beta-thalassemia (thal) phenotype caused by the rare Hb Showa-Yakushiji [beta110(G12)Leu-->Pro, CTG-->CCG] mutation in combination with an alpha gene triplication. This combination of two rare mutations was observed during hemoglobinopathy carrier diagnostics in a 26-year-old Dutch female at 9 weeks gestation, at the first pregnancy examination in the midwives practice. The partner was promptly examined and no abnormalities were found. The beta-thal trait was diagnosed by a standard high performance liquid chromatography (HPLC) procedure showing a normal separation but an elevated Hb A(2) level of 5.9% in the presence of pronounced hypochromic microcytic parameters and mild chronic hemolysis. Direct sequencing of the beta-globin genes was subsequently performed revealing a CTG-->CCG transition at codon 110. This rare mutation was previously described as two independent events in a few Japanese and Indian individuals. The mutation induces a Leu-->Pro substitution and the gene product is highly unstable. Gap-polymerase chain reaction (gap-PCR) revealed a heterozygosity for the alpha gene triplication as well. The excess of alpha-globin chains contributed only marginally to the hematological abnormalities of the patient and did not aggravate the phenotype to an intermediate level.

We report a new hemoglobin (Hb) variant found in a 6-year-old girl of Moroccan origin, living in the Dutch city of Gouda. The child was referred because of microcytic and hypochromic parameters. A normal zinc protoporphyirin (ZPP) value excluded iron deficiency and gap-polymerase chain reaction (gap-PCR) revealed a heterozygosity for the common -alpha(3.7) thalassemia deletion, partially justifying the hematological picture. The Hb pattern on alkaline electrophoresis and capillary electrophoresis was normal, while a fraction of 9% preceding the Hb A peak, remained visible on different high performance liquid chromatography (HPLC) devices. This fraction, located in front of the Hb A peak, is usually considered as a Hb A derivate that becomes more expressed in older samples. However, the sample was freshly collected and the peak unusually evident. Therefore, direct sequencing of the alpha-globin genes was performed revealing a GTG-->CTG transversion at codon 1 of the alpha1-globin gene or of the hybrid gene. This point mutation induces a single amino acid substitution from valine to leucine. Electrospray-mass spectrometry (ES-MS) analysis revealed, in addition to this substitution, that the N-terminal methionine was retained and that about 20% of the variant was acetylated. As expected for an association with a -alpha(3.7)-thalassemia (thal) deletion, the non acetylated and acetylated abnormal alpha chain amounted to 32% of the total alpha chains. Family studies revealed that the mutated codon was located in cis of the deletion.

Hb Groene Hart [alpha119(H2)Pro-->Ser, CCT-->TCT (alpha1)] has been reported in heterozygotes of Moroccan origin and also in association with the common -alpha(3.7) deletion. In all cases, the mutated protein was not detectable but was apparently associated with a mild alpha-thalassemia (thal) phenotype, presumably due to a modification of the alpha-globin chain domain that is recognized by the a hemoglobin stabilizing protein (AHSP). The present case of Hb Groene Hart homozygosity, confirms that the alpha-thal phenotype is associated with this alpha-globin chain. Hb Groene Hart must be quite frequent not only in Morocco but probably also among the northern African coastal population.

A 52-year-old Dutch male was referred to our laboratory for hemoglobinopathy analysis because of persistent microcytic hypochromic parameters and moderate erythrocytosis in the absence of iron deficiency. The hemoglobin (Hb) pattern was normal and breakpoint polymerase chain reaction (PCR) excluded the six common deletion defects of the alpha gene cluster. Direct sequencing revealed a GCT-->TCT transversion at codon 21 of the alpha2 gene generating an Ala-->Ser single amino acid substitution. The hematological parameters observed in the presence of this mutation are consistent with a compensated heterozygous alpha(+)-thalassemia (thal). However, the neutral mutation and the external position of the residue do not explain an association with this phenotype. Nevertheless, we cannot exclude that the mutation could induce the observed hematological abnormalities and could eventually be considered as a mutation associated with a mild alpha-thalassemic phenotype.

We report a new structural defect of the alpha2-globin chain, not detectable on high performance liquid chromatography (HPLC) or electrophoresis, characterized in a 12-year-old boy of Surinamese-Hindustani origin. The child was suspected to be a carrier of alpha-thalassemia (thal) because of microcytic hypochromic parameters in the absence of iron depletion. Gap-polymerase chain reaction (gap-PCR) revealed only normal fragments in the proband, and the pattern of a -alpha4.2 (leftward) deletion in his father and sister. Direct sequencing of the alpha-globin genes revealed an ACC-->AAC transversion at codon 108 of the alpha2-globin gene in the proband, in his mother and in a younger sister. The new mutation predicts a Thr -->Asn amino acid substitution at the corresponding residue. Threonine, a covalent binder with an R-active OH group, situated in the G helix of the alpha-globin chain, is involved in alpha1beta1 contacts. Asparagine, being an equally covalent binder but with a different R-active H2N-C=O group, could make the mutated chain less suitable for tetramer cooperation. Alternatively, an absent or reduced interaction with the alpha hemoglobin (Hb) stabilizing protein (AHSP) could lead to loss of alpha chains. Hb Bleuland is the first mutation described at codon 108 and is therefore interesting in regard to the possible effects and genetic risk. The nearest variant, Hb Suan-Dok [alpha109(G16)Leu -->Arg, CTG-->CGG (alpha2)] was originally observed in a Thai patient affected with Hb H, in combination with an alpha0-thal allele. The same Hb Suan-Dok mutation, recently described in our laboratory in a carrier of African ancestry, was also not detectable as a protein and presented with an alpha-thal phenotype similar to Hb Bleuland.

We have characterized a new abnormal hemoglobin (Hb) at position 32 of the alpha-globin chain. The proband, a 38-year-old woman of Surinamese Black ancestry, was referred to the Academic Hospital in Amsterdam, The Netherlands, after 3 years of Prednisone treatment in Surinam. Kidney failure was diagnosed at the Nephrology Department, Free University Medical Center, Amsterdam, The Netherlands; the cortisone treatment was interrupted and dialysis was started. At this stage, a microcytic hypochromic anemia was observed with high reticulocyte (40%) and ferritin (500 microg/L) levels, and hemoglobinopathy was suspected. No abnormal bands were visible on alkaline electrophoresis and high performance liquid chromatography (HPLC). The Hb A2 level was normal (2.7%) and the erythrocyte count was low (3.59 x 10(12)/L) with a normal haptoglobin level (68 mg/100 mL). None of the common alpha-thalassemia (thal) deletion defects were present. The beta-globin gene sequence was normal but the alpha2-globin gene sequence revealed an ATG-->ATA transition at codon 32, changing the methionine into an isoleucine residue. The mutation, called Hb Amsterdam, was observed in the mother of the proband, who was also heterozygous for the--alpha3.7-thal deletion and affected by a moderate microcytic hypochromic anemia. Both Hb Amsterdam and the--alpha(-3.7) allele were found in association with a new polymorphism, IVS-I-39 (C-->T), previously observed in our laboratory in seven patients of African origin, on both the alpha1 and alpha2 genes. In addition, Hb Amsterdam was also associated with the common African alpha2 polymorphism (G-->CTCGGCCC at position 7238 and T-->G at position 7174). Hb Amsterdam is the first mutation ever described at codon alpha32, a position involved in alpha1/beta1 interaction. The possibility of a contribution of this mutation to the nephropatic state of the proband is discussed.

We describe the characterization of a new hemoglobin (Hb) variant found in a 77-year-old Dutch woman, suspected of hypoxia-mediated erythrocytosis. The typical blood parameters (Hb 17.3 g/dL; PCV 0.525 L/L; RBC 5.82 x 10(12)/L) could not be explained by any of the pathological or physiological conditions causing erythrocytosis. The patient was preventively phlebotomized because of intermittent claudication and erythrocytosis. At the hematological and biochemical levels, no anemia or hemolysis were present and no abnormal Hb fractions were detectable on alkaline electrophoresis or high performance liquid chromatography (HPLC). Molecular analysis revealed intact alpha-globin genes and a heterozygosity for a GTT-->GCT transition at codon 23 of the beta-globin gene, causing a Val-->Ala amino acid substitution. The P50 measured in full blood indicated that this mutant has an elevated oxygen affinity. This is the fourth single nucleotide substitution at codon 23 of the beta gene and the second associated with erythrocytosis. Because the family was not available for investigation no information was obtained as to whether the mutation represents a de novo event or was inherited, and might be a more common cause of erythrocytosis in Dutch patients. Considering the relatively high frequency of beta-thalassemia (thal) in the large allochthonous population in The Netherlands, combinations of Hb Zoeterwoude and beta-thal traits may lead to hemizygosity, with severe hypoxia and erythrocytosis from a few months after birth.

An abnormal hemoglobin (Hb) fraction was observed during a high performance liquid chromatographic (HPLC) Hb A1c control for diabetes mellitus in a 56-year-old north European woman. Family analyses revealed the abnormal fraction in three of her five siblings and in her son. Elevated Hb and packed cell volume (PCV) values and red blood cell (RBC) counts were present in all carriers. No histories of anemia, hemolytic or circulatory episodes were reported. The abnormal Hb fraction estimated at 40%, migrated just below Hb F on alkaline electrophoresis and overlapped the Hb A2 peak on cation exchange HPLC. Direct sequencing of the beta-globin genes revealed a new GAC --> TAC transversion in heterozygous form at codon 94 of the beta-globin gene. Based on the hematological/biochemical data and the decreased P50 value, we conclude that the new variant is a stable Hb associated with a slightly elevated oxygen affinity.

A microcytic hypochromic anemic state was observed in an 8-year old Black female of Surinam origin during pre-operative Hb S [beta6(A3)Glu-->Val] screening. Her high zinc protoporphyrin (ZPP) level suggested a chronic iron depletion but, in contrast, the high red blood cell (RBC) count (5.85 x 10(12)/L) was indicative of a possible coexisting thalassemia. No abnormal hemoglobin (Hb) bands were present on high performance liquid chromatography (HPLC) or alkaline electrophoresis and the Hb A2 level was normal. Break point polymerase chain reaction (PCR) failed to reveal any of the common alpha-thalassemia (thal) mutations but selective DNA sequencing of both alpha-globin genes disclosed a TGC-->AGC transversion at codon 104 of the alpha1 gene. Cystine at codon 104 is involved in alpha/beta globin contact and has been described to be a critical amino acid of the alpha2 chain when substituted by a tyrosine (Hb Sallanches), inducing Hb H (beta4) disease in the homozygous state. Our heterozygous patient had a moderate anemia of 12.2 g/dL and a borderline haptoglobin suggesting some degree of hemolysis.

A 58-year-old Black female from Curaçao (West Indies) was recently referred to our Laboratory for a persistent microcytic hypochromic anemia. An analysis 13 years earlier had shown no abnormal hemoglobin (Hb) fractions and a balanced beta/alpha synthetic ratio. The hematological indices were again compatible with thalassemia and no abnormal fractions were observed on electrophoresis or high-performance liquid chromatography (HPLC). None of the seven common alpha-thalassemia (thal) deletion defects were present. Direct sequencing of the alpha2 gene revealed a CTG-->CGG single base substitution at codon 109. This mutation was previously described in a Thai patient (Hb Suan-Dok), inducing Hb H disease in association with a - -(SEA) allele. In contrast with earlier reports we were unable to identify any native Hb fraction. The balanced beta/alpha ratio indicated that alpha2-Suan-Dok is formed but does not form tetramer formation unless alpha-thal is present.

The hemoglobin (Hb) pattern of a 32-year-old Somali male living in The Netherlands, during routine diabetes mellitus monitoring, showed two more peaks in addition to the characteristic heterozygous Hb A/S pattern. A major peak of 15% faster than Hb A, and a minor one of 10.8%, overlapping Hb A2 and the glycated Hb S1c fraction were present. The patient was not anemic or microcytic but had a low haptoglobin level, possibly indicating a slightly elevated red blood cell (RBC) turnover. Hb S was confirmed by a sickle test and at the DNA level. The DNA sequence of the alpha1 gene revealed a C-->G transversion at position 89, changing the local positively charged histidine to a neutral glutamine. This mutant has been previously described in a Yemenite woman and two apparently unrelated Somali males. Our case is the first showing Hb Buffalo in combination with Hb S and a G6PD deficiency, and is again observed in a Somali. No functional abnormalities associated with mutations at this amino acid residue are reported in the literature. Also, in this case no sign of any hematological abnormalities that could not be explained by the Hb S heterozygosity G6PD deficiency was found. The abnormal alpha chain is expressed at the expected rate and without thalassemic effect or instability. The mutated alpha chain seems to associate with a slight preference to the beta(A) (15%) rather than with the beta(S) counterpart. The sum of both Hb A(Buffalo) and Hb S(Buffalo) results in about 19-20% of total Hb. This figure is in agreement with a stable mutant of the alpha1 gene.

Hb Evanston [alpha14(A12)Trp --> Arg] is considered to be a rare alpha chain mutant, and was originally observed in two Black families in 1982, inducing a mild Hb H disease phenotype in a homozygous state for the -alpha3.7 deletion ( -alpha(Evanston)/ -alpha). The mutant, evidently linked with one of the two -alpha3.7 thalassemia (thal) alleles, was considered to be unstable and rapidly proteolyzed. We describe Hb Evanston in three new independent Asian cases, all induced by a TGG --> CGG transition. In all cases the mutation is linked to the alpha1-globin gene, either on a wild type allele or in linkage with the common -alpha3.7 and -alpha4.2 deletion alleles. The beta/alpha ratio was balanced in the presence of the mutation only, and accordingly unbalanced in co-inheritance with the deletion defects. Although a second independent mutation event on a -alpha3.7 or a -alpha4.2 deletion allele could not be excluded, we conclude that at least one independent Hb Evanston mutation has occurred on a wild type allele in the Asian populations. Unstable Hb tetramers tend to degrade and disappear during purification. Both Hb Evanston tetramers, formed in combination with normal beta and delta chains, remain perfectly stable after extensive purification and concentration steps, suggesting an early posttranslational thalassemic effect, probably at the dimer/tetramer affinity level.

Alpha-Thalassemia (thal) is generally considered to be an expression defect caused mostly by deletions silencing one or more alpha-globin genes. Although nondeletional alpha-thalassemia is considered rare, in our laboratory we frequently observe alpha-thal phenotypes induced by point mutations. We report a new point mutation generating an abnormal hemoglobin (Hb) associated with a mild alpha-thal phenotype in two members of a Moroccan family, who presented with mild but persistent microcytic hypochromic parameters and a balanced beta/alpha synthetic ratio. All attempts to separate an abnormal native or denatured fraction were unsuccessful using electrophoresis, isoelectrofocusing (IEE), ion exchange and reversed phase high performance liquid chromatography (HPLC), denaturing polyacrylamide gel electrophoresis (PAGE), and electrospray mass spectrometry (ES/MS). The anomalous protein was only predictable by DNA analysis. The mutated gene product, not separable with any of the techniques used, could be a monomer unsuitable for tetramer formation, which is proteolyzed at an early stage. Alternatively, this mutation could perhaps lead to an abnormal splicing. The CCTCT sequence generated by the mutant, not found in the translated region of the gene, but normally present at the end of the IVS-II, could induce a possible exon skipping. This mutant could generate a mild or a critical Hb H disease in combination with one of the common alpha0-thal deletion defects.

We describe a new structural mutant of the beta-globin chain in a 17-year-old Dutch Caucasian girl. The mutant is associated with a severe pathology as a consequence of hyper-instability of the hemoglobin tetramer. The proband, whose parents had no history of hemolysis, was admitted to the hospital at 5 months of age with hemolytic anemia and splenomegaly. No indications for autoimmune defects or enzymopathies were found. Repeated hemoglobin electrophoresis on cellulose acetate revealed no abnormalities. At the age of 17 years, a minor abnormal band of less than 1% was detected on starch gel electrophoresis, migrating slightly faster than Hb A2. Sequencing of the beta-globin gene revealed heterozygosity for a 4 bp deletion (GCTA) in combination with a 1 bp insertion (T) at codons 138/139. This event eliminates two amino acids (Ala-Asn) and introduces a new residue (Tyr). We discuss the hematological and the pathophysiological consequences of this mutant, which is fully expressed as a gene product, and apparently assembled into unstable tetramers that precipitate shortly after.

We describe a new alpha 2-globin gene point mutation found in six individuals of a three-generation Dutch family. The mutant, which is associated with a mild alpha-thalassaemic phenotype, is not detectable at the protein level. The alpha 2 cd129 (CTG-->CCG) transition was found by molecular analysis using denaturing gradient gel electrophoresis (DGGE) and single-strand conformation analysis (SSCA) followed by direct sequencing of the alpha 2-globin gene. Southern analysis revealed a triplication of the zeta-gene in cis with the mutant alpha-globin gene.