Hb J-Paris-I [HBA2: c.38C>A (or HBA1)] is a stable fast-moving hemoglobin (Hb) that elutes in the P3 window on high performance liquid chromatography (HPLC). The mutation can happen on either the alpha 1- or alpha 2-globin gene. Codon 12 changes from GCC to GAC to replace the alanine amino acid with aspartic acid. This change is external with no clinical significance. The elution in the P3 wave on HPLC can interfere with the glycated Hb assay by HPLC. In this study, data of 11 cases of Hb J-Paris-I were thoroughly presented. The majority of the cases were of Indian ethnicity. The mean value of Hb J-Paris-I on HPLC was 26.7 +/- 2.0%. The retention time (RT) was 1.75 +/- 0.03 min. The isoelectric focusing (IEF) mean value was -5.6 (range -6.1 to -4.9). Hb A(2) was consistently reduced to 1.8 +/- 0.3%. A fraction of 0.8% corresponding to the Hb A(2)-J-Paris-I (alpha(J-Paris-I)(2)delta(2)) is likely to be concealed within the A(0) peak of Hb A on HPLC. Interestingly, two cases were associated with two different polymorphisms [HBA2: c.-24C>G or Cap +14 (C>G) and HBA2: c.*136A>G polymorphism] without apparent effect on the variant expression.

Hb Winnipeg [α75(EF4)Asp→Tyr (α2); HBA2: c.226G>T (or HBA1)] is a stable α-globin chain variant described in a few articles. The majority of reported cases in older articles were clustered in Canada. It can occur on both α1- and α2-globin genes and in different populations. In this study, eight cases of Hb Winnipeg were characterized by DNA sequencing during a wide-spectrum study of suspected α-globin gene variants collected in the United Kingdom. All cases detected peaked in the S window between 4.4 and 4.54 min. on high performance liquid chromatography (HPLC). The isoelectric focusing (IEF) averaged at 6.21 below Hb A. All the mutations were detected on the α1-globin gene except in one case. The ethnic origin of the majority of the patients was Canadian. Only one case was associated with the common polymorphism HBA2: c.-24C>G (or HBA1) [Cap +14 (C>G)] on both α-globin genes without any apparent effect on the variant expression. All cases were detected in a heterozygous state. Hb Winnipeg expression was consistently lower than the theoretical value for α chain variants, ranging between 11.8 and 15.8% of total hemoglobin (Hb). This study gave more details about Hb Winnipeg that may help in presumptive diagnosis, especially in routine laboratories.

Hb J-Meerut [HBA2: c.362C>A (orHBA1)] is a rare, stable, nonpathogenic alpha-globin gene variant that peaks in the area between the P3 and A(0) windows on high performance liquid chromatography (HPLC). Few cases from different ethnic origins have been published but the majority were Asian Indians. Coinheritance with other hemoglobin (Hb) variants are rarer and can change the Hb J-Meerut phenotype making a diagnostic dilemma. In this study, we have reported 15 cases of Hb J-Meerut, discovered during a wide spectrum study of alpha-globin chain variants in the UK. The diagnosis was confirmed by forward and reverse DNA sequencing of the alpha 1- and alpha 2-globin genes. The average of the Hb J-Meerut expression was 20.9% of total Hb and characterized by a retention time (RT) of 1.9 min. (on average) on HPLC. The median of isoelectric focusing (IEF) was 5.6 mm above Hb A. Among the 15 cases studied, one case coinherited the Hb E (HBB: c.79G>A) mutation in heterozygosity and another case was associated with the Cap +14 (C>G) [HBA1: c.-24C>G (orHBA2)] variant. We noticed that the coinheritance of the Hb E mutation reduced the Hb J-Meerut expression with the formation of a hybrid peak missed on the HPLC chromatograph. We also noticed an increased expression of Hb J-Meerut in the case showing the coinheritance of theHBA2: c.-24C>G (orHBA1) variant.

Hb Manitoba [alpha 102(G9)Ser -> Arg] is a rare alpha chain variant with diverse ethnic origins. It is mildly unstable with an expression of around 10.0-14.2% in the heterozygous state in most literature. In this study, 12 cases of Hb Manitoba [11 cases carried Hb Manitoba II (HBA1: c.309C>A) and one case carried Hb Manitoba IV (HBA1: c.307A>C)] were detected during a wide-spectrum study of alpha chain variants in the UK. Fluctuation in variant expression from 6.9 to 15.2% of total Hb on high performance liquid chromatography (HPLC) would pose a diagnostic dilemma in routine laboratories. Focusing on the variant expression, the median of Hb Manitoba was around 11.5% of total Hb in three cases, apparently with normal hemoglobin (Hb), and normal red blood cell (RBC) indices. Two cases showed a higher expression (13.9 and 15.2%) and five cases showed a lower expression (6.9-9.9%). The common alpha-thalassemia (alpha-thal) -alpha(3.7) (rightward) deletion coexisted with one case of increased Hb Manitoba expression. Iron (or other nutrient) deficiency was likely the cause of decreased Hb Manitoba percentage in this study. The alpha 73(EF2)Val -> Val (alpha 2) (HBA2: c.222G>T) polymorphism is published for the first time and coexisted with two cases. The Cap +14 (C>G) (HBA2: c.-24C>G) polymorphism coexisted with another case in a heterozygous state. In conclusion, the fluctuation in variant expression can cause a diagnostic dilemma, especially in routine laboratories. Screening for the common -alpha(3.7) deletion and iron deficiency is recommended when an alpha chain variant is suspected.

Over many years, cases of suspected α-globin chain variants were collected from different parts of the UK. The suspicion was based on the clinical picture, high performance liquid chromatography (HPLC) variant percentage, retention time (RT) and isoelectric focusing (IEF). DNA sequencing and the restriction enzyme EaeI were used for definitive diagnosis. One hundred and forty-eight variants were confirmed on one or both of the two α-globin genes (HBA2, HBA1). These cases were identified as 46 different α-globin chain variants. The most common variants were Hb J-Meerut [HBA2: c.362C>A (or HBA1)] (10.1%) and Hb Q-India (HBA1: c.193G>C) (8.1%), followed by Hb J-Paris-I [HBA2: c.38C>A (or HBA1)] and Hb Manitoba II (HBA1: c.309C>A) (7.4% for each). Other α variants were detected at lower frequencies. Two novel alleles were also detected: Hb Walsgrave [α116(GH4)Glu→Val (HBA2: c.350A>T)] and Hb Coombe Park [α127(H10)Lys→Glu (HBA2: c.382A>G)]. The majority of the ethnic origin was Indian. The positive predictive value for α variant identification by HPLC-RT analysis was 65.9%, 41.9% by IEF, and using both RT and IEF, the value was 72.1%. The number of variants was higher in HBA1 than in HBA2 genes and in exons 1 and 2 than in exon 3. There was no clustering of mutations in consecutive codons. This study, the characterization of a wide spectrum of α-globin chain variants, can facilitate the presumptive diagnosis of these variants prior to screening by a panel of amplification refractory mutation system-polymerase chain reaction (ARMS-PCR), and a definitive diagnosis by DNA sequencing.

The current influx of economic migrants and asylum seekers from countries with a high prevalence of haemoglobinopathies creates new challenges for health care systems and diagnostic laboratories. The migration of carriers introduces new and novel haemoglobinopathy mutations to the diagnostic repertoire of a laboratory, often creating new pressures to improve and update the carrier screening technology and diagnostic scope. For antenatal screening programmes, the marriage of partners from different ethnic groups can lead to the risk of compound heterozygote children being born novel mutation combinations, creating problems in the provision of accurate advice regarding the expected phenotype of the thalassaemia or haemoglobinopathy disorder. In the UK, the impact of immigration required the National Haemoglobinopathy Reference laboratory to change the strategy and techniques used for the molecular diagnosis of thalassaemia and the haemoglobinopathies. In 2005, due to the increasingly large range of β-thalassaemia mutations that needed to be diagnosed, the laboratory switched from a three-step screening procedure using ARMS-PCR to a simpler but more expensive one-step strategy of DNA sequencing of the beta and alpha globin genes for all referrals. After ten years of employing this strategy, a further 57 novel thalassaemia and haemoglobionpopthy alleles were discovered (11 new β-chain variants, 15 α-chain variants, 19 β-thalassaemia mutations and 12 α+-thalassaemia mutations), increasing further the extremely heterogeneous spectrum of globin gene mutations in the UK population.

Carrier screening for the haemoglobinopathies has undergone many technological improvements in haematological and molecular diagnostic techniques since the first prenatal diagnoses by DNA analysis in the 1970s by Southern blot analysis enabled the implementation of effective successful prevention programmes for beta thalassaemia involving public education, carrier screening, genetic counselling and prenatal diagnosis in Mediterranean countries. The application of a wide variety of PCR-based molecular diagnostic techniques which allows the detection of the complete range of haemoglobinopathy mutations has led to the establishment of comprehensive national prevention programmes in many developing countries and also in countries such as those in Northern Europe in which the prevalence and heterogeneity of the haemoglobinopathies has been significantly increased by population immigration. Despite the great technological advances in mutation detection, the screening of haemoglobinopathies still requires the combined use of haematological and molecular techniques to arrive at an accurate diagnosis, and requires specialist knowledge of genotype/phenotype relationships because of the multitude of complex phenotypes which result from interactions between genotypes and co-inherited globin gene disorders relationships. The latest technological advances in mutation analysis techniques and the application of some of these for the noninvasive approach of analysis of fetal DNA in maternal blood are anticipated to improve haemoglobinopathy prevention programmes in the future.

Haemoglobinopathies constitute the commonest recessive monogenic disorders worldwide, and the treatment of affected individuals presents a substantial global disease burden. Carrier identification and prenatal diagnosis represent valuable procedures that identify couples at risk for having affected children, so that they can be offered options to have healthy offspring. Molecular diagnosis facilitates prenatal diagnosis and definitive diagnosis of carriers and patients (especially 'atypical' cases who often have complex genotype interactions). However, the haemoglobin disorders are unique among all genetic diseases in that identification of carriers is preferable by haematological (biochemical) tests rather than DNA analysis. These Best Practice guidelines offer an overview of recommended strategies and methods for carrier identification and prenatal diagnosis of haemoglobinopathies, and emphasize the importance of appropriately applying and interpreting haematological tests in supporting the optimum application and evaluation of globin gene DNA analysis.

A molecular study of Hb Lepore heterozygotes identified by the UK population screening program has revealed four out of the five known Lepore variants. The region of homologous δ- and β-globin gene sequence was determined in 58 unrelated Hb Lepore heterozygotes referred for confirmation of their carrier status by DNA analysis through the national thalassemia and sickle cell screening program over a period of 10 years. The most common variant found was Hb Lepore-Boston-Washington (Hb LBW, HBD: c.265 C > c.315 + 7 C) observed in 46 carriers (79.0%). Hb Lepore-Hollandia (HBD: c.69 A > c.92 + 16 A) was found in nine cases (16.0%); Hb Lepore-Baltimore (HBD: c.208 G > c.254 C) in two cases (4.0%) and Hb Lepore-ARUP (HBD: c.97 C > c.150 C) in one carrier (2.0%). Analysis of the hematological findings showed no significant differences between the four groups. The wide range of Hb Lepore variants observed in this study confirms the very diverse range of α- and β-globin gene mutations observed in the UK population by previous studies.

Abstract We review and report here the genotypes and phenotypes of 60 novel thalassemia and abnormal hemoglobin (Hb) mutations discovered following the adoption of routine DNA sequencing of both α- and β-globin genes for all UK hemoglobinopathy samples referred for molecular investigation. This screening strategy over the last 10 years has revealed a total of 11 new β chain variants, 15 α chain variants, 19 β-thalassemia (β-thal) mutations and 15 α+-thalassemia (α+-thal) mutations. The large number of new thalassemia alleles confirms the wide racial heterogeneity of mutations in the UK immigrant population. Eleven of the new variants ran with Hb A on high performance liquid chromatography (HPLC), demonstrating the value of routine sequencing of both α- and β-globin genes for all hemoglobinopathy investigations. The new β chain variants are: Hb Bury [β22(B4)Glu  →  Asp (HBB: c.69A > T)], Hb Fulwood [β35(C1)Tyr → His (HBB: c.106T > C)], Hb Little Venice [β42(CD1)Phe → Cys (HBB: c.128T > G)], Hb Cork [β57(E1)Asn → Ser (HBB: c.173A > G), Hb Basingstoke [β118(GH1)Phe → Ser (HBB: c.356T > C)], Hb Howden [β20(B2)Val → Ala (HBB: c.62T > C)], Hb Wilton [β41(C7)Phe → Leu (HBB: c.126C > A)], Hb Belsize Park [β120(GH3)Lys → Asn (HBB: c.363A > T)], Hb Hampstead Heath [β2(NA2)His → Gln;β26(B8)Glu → Lys (HBB: c.[6C > G;79G > A])], Hb Grantham [β85(F1)Phe → Cys (HBB: c.257T > G)] and Hb Calgary [β64(E8)Gly → Val (HBB: c.194G > T). The new α chain variants are: Hb Edinburgh [α70(E19)Val → Gly (HBA2: c.212T > G)], Hb Walsgrave [α116(GH4)Glu → Val (HBA2: c.350A > T)], Hb Wexham [α117(GH5) and 118(H1) insertion Ser (HBA1: c.354-355insTCA)], Hb Coombe Park [α127(H10)Lys → Glu (HBA2: c.382A > G)], Hb Oxford [α17(A15)Val → Asp (HBA2: c.53T > A)], Hb Bridlington [α32(B13)Met → Thr (HBA1: c.98T > C), Hb Wolverhampton [α81(F2)Ser → Tyr (HBA2: c.9245C > A)], Hb Little Waltham [α13(A11)Ala → Asp (HBA2: c.41C > A)], Hb Derby [α61(E10)Lys → Arg (HBA1: c.185A > G)], Hb Uttoxter [α74(EF3)Tyr → Asp (HBA2: c.223G > T)], Hb Harehills [α124(H7)Ser → Cys (HBA1: c.374C > G)], Hb Hekinan II [α27(B8)Glu → Asp (HBA1: c.84G > T)], Hb Manitoba IV [α102(G9)Ser → Arg (HBA1: c.307A > C), Hb Witham [α139(HC1)Lys → Arg (HBA2: c.419A > G) and Hb Farnborough [α9(A7)Asn → Asp (HBA1: c.28A > G). In addition, 10 more paralogous α-globin chain variants have been discovered. The novel β-thal alleles are: HBB: c.-138C > G, HBB: c.-121C > T, HBB: c.-80T > G, HBB: c.18_19delTG, HBB: c.219_220insT, HBB: c.315 + 2_315 + 13delTGAGTCTATGGG, HBB: c.316-70C > G, HBB: c.345_346insTGTGCTG, HBB: c.354delC, HBB: c.376-381delCCAGTG, HBB: c.393T > A, HBB: c.394_395insA, HBB: c.375_376insA, HBB: c.*+95_*+107delTGGATTCTinsC, HBB: c.* + 111_*+112delAA, HBB: c.*+112A > T, HBB: c.394C > T, HBB: c.271delG and HBB: c.316-3C > T. The novel α + -thal alleles are: HBA1: c.95+1G > C, HBA1: c.315C > G [Hb Donnington, α104(G11)Cys → Trp], HBA1: c.327delC, HBA1: c.333_345del, HBA1: c.*+96G > A, HBA2: c.2T > G, HBA2: c.112delC, HBA2: c.143delA, HBA2: c.143_146delACCT, HBA2: c.156_157insG, HBA2: c.220_223delGTGG, HBA2: c.305T > C [Hb Bishopstown, α101(G8)Leu → His], HBA2: c.169_170delAA, HBA2: c.1A > T and HBA2: c.-3delA.

We report here the spectrum of delta-globin gene mutations found in the UK population. Nine different delta chain variants and two delta-thalassemia (delta-thal) mutations were characterized in a study of 127 alleles in patients with either a low Hb A(2) value or a split Hb A(2) peak on high performance liquid chromatography (HPLC). The most common d chain variant was Hb A'(2) (or Hb B-2) [delta 16(A13)Gly -> Arg; HBD: c.49G>C] (77.0%), followed by Hb A(2)-Yialousa [delta 27(B9)Ala -> Ser; HBD: c.82G>T] (12.0%), Hb A(2)-Babinga [delta 136(H14)Gly -> Asp; HBD: c.410G>A] (3.0%), Hb A(2)-Troodos [delta 116(G18)Arg -> Cys; HBD: c.349C>T] (1.0%), Hb A(2)-Coburg [delta 116(G18)Arg -> His; HBD: c.350G>A] (2.0%) and Hb A(2)-Indonesia [delta 69(E13)Gly -> Arg; HBD: c.208G>C] (1.0%). Three novel variants were identified: Hb A(2)-Calderdale [codon 2 (CAT>AAT), His -> Asn; HBD: c.7C>A], Hb A(2)-Walsgrave [codon 52 (GAT>CAT), Asp -> His; HBD: c.157G>C] and Hb A(2)-St. George's [codon 81 (CTC>TTC), Leu -> Phe; HBD: c.244C>T]. In addition, two known delta-thal mutations were observed: -68 (C>T); HBD: c.-118C>T and codon 4 (ACT>ATT); HBD: c.14C>T. Amplification refractory mutation system (ARMS) primers were developed to provide a simple molecular diagnostic test for the most common variant, Hb A'(2). Three of the variants had a characteristic HPLC retention time that can be used for a presumptive diagnosis.

Inherited haemoglobinopathies are the most common monogenic diseases, with millions of carriers and patients worldwide. At present, we know several hundred disease-causing mutations on the globin gene clusters, in addition to numerous clinically important trans-acting disease modifiers encoded elsewhere and a multitude of polymorphisms with relevance for advanced diagnostic approaches. Moreover, new disease-linked variations are discovered every year that are not included in traditional and often functionally limited locus-specific databases. This paper presents IthaGenes, a new interactive database of haemoglobin variations, which stores information about genes and variations affecting haemoglobin disorders. In addition, IthaGenes organises phenotype, relevant publications and external links, while embedding the NCBI Sequence Viewer for graphical representation of each variation. Finally, IthaGenes is integrated with the companion tool IthaMaps for the display of corresponding epidemiological data on distribution maps. IthaGenes is incorporated in the ITHANET community portal and is free and publicly available at http://www.ithanet.eu/db/ithagenes.

This chapter presents a brief outline of the structure, function, and biosynthesis of the normal human hemoglobins, and then discusses the current knowledge of the clinical diseases associated with defects in globin synthesis, their molecular pathology, diagnosis, and treatment. The different types of hemoglobin variants are summarized, with particular emphasis on those that exhibit a clinically significant change in their functional properties—the unstable hemoglobins, variants with altered oxygen affinity and the M hemoglobins that result in congenital cyanosis. A major portion of the chapter is devoted to the sickle-cell disorders, describing the genetics and geographical distribution of Hb S, the clinical aspects of sickle-cell disease and its diagnosis, treatment and prevention, and a brief review of the interactions of Hb S with other hemogobinopathies. Finally, the molecular basis of the alpha and beta thalassemias is reviewed, with an up-to-date listing of the mutations and a brief discussion of the molecular effects of each category of gene defect. The clinical features of the thalassemia are described and the process of carrier identification is outlined, together with the most commonly used methods of molecular identification of the thalassemia mutations, and the current approaches to therapy and prevention.