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Unstable hemoglobin Rush [beta 101(G3) Glu > Gln, HBB:c.304G > C] in a Brazilian family with moderate hemolytic anemia
Abstract
Hemoglobin Rush is an unstable variant generated by a mutation of the β-globin gene which causes amino acid replacement Glu>Gln in the central cavity of hemoglobin (G3). Many members of a Brazilian family of Italian descent have hemoglobin Rush. This is the second report in world literature. Clinical and laboratory features were retrieved and gene mutation was characterized. Hemoglobin electrophoresis, gene sequencing, and restriction fragment length polymorphism with Hpy188I were used to characterize it. In 13 affected members, hemoglobin ranged from 9.3 to 13.0 g/dL and reticulocyte count up to 12.8%. The intensity of hemolysis appeared to be linked to increased stress. The mutation was proved to be HBB:c.304G>C, beta 101(G3) Glu>Gln. Heterozygous hemoglobin Rush should be suspected when alkaline electrophoresis shows three bands, whereas isoelectric focusing and acid electrophoresis show only two. Adequate genetic counseling to avoid intermarriage should be provided because homozygous hemoglobin Rush is predicted to be clinically severe.
... Unstable hemoglobin (Hb) Rush [Beta 101(G3) Glu > Gln, HBB:c.304G > C] is one of the early identified hemoglobin variants has been described to be responsible for mild hemolytic anemia in an African-American family and a Brazilian family of Italian descent [4,5]. As only a few Hb Rush simple heterozygotes have been reported in the two isolated families, many characteristics about its clinical features still remain unclear. ...
... Unstable Hb Rush variant is a rare hemoglobin disorder previously described in only two unrelated families [4,5], and knowledge of its genotype-to-phenotype relationship is limited and unrecognized. The present study found that the most of Hb Rush simple heterozygote were asymptomatic, yet moderate anemia (HGB 85 g/L) was observed in one patient (subject P3 in Table 1), suggesting that the clinical presentation of a simple heterozygous Hb Rush maybe heterogeneous. ...
... However, the migration of the Hb Rush faction is very similar to that of Hb F on these electrophoreses. As shown in our results, Hb Rush is distinguishable from Hb F on gel electrophoresis (Figure 2A), thus potentially confounding diagnosis [4,5]. Our findings revealed the capillary electrophoresis pattern of Hb Rush, which showed clearly separation of Hb Rush from the Hb F fraction ( Figure 2B). ...
Background: The clinical consequences and significance of many unstable hemoglobins interacting with other hemoglobinopathies remain unrecognized. Here we first explore molecular and hematological characterizations of previously undescribed compound heterozygosity states for unstable hemoglobin Rush (Hb Rush, Beta 101 Glu > Gln, HBB:c.304G > C) with Hb E and different forms of thalassemia.
Methods: Hematological assays, globin gene mutation assays and β-globin gene cluster haplotype were conducted in 11 patients from 8 unrelated Chinese ethnic families with unexplained hemoglobin separation fraction in hemoglobin gel electrophoresis.
Results: Hb Rush in various combinations with Hb E, β⁰-thalassemias and α⁺-thalassemia were identified. Hb Rush simple heterozygote was generally associated with mild hemolytic anemia, and the compound heterozygotes of Hb Rush and the other β-globin variants led to thalassemia intermedia phenotypes with moderate anemia. Hemoglobin electrophoreses showed that the co-presence of Hb Rush with either Hb E or β⁰-thalassemias increased proportion of Hb Rush due to relative decrease of other globin chain synthesis. Beta-globin gene cluster haplotype analysis suggested a common origin of the Hb Rush variant in the Chinese families of different ethnic ancestry.
Conclusions: Unstable Hb Rush interacting with β-thalassemia result in thalassemia intermedia phenotypes, which demonstrated the clinical significance of Hb Rush and new insights into complex mechanism of clinical heterogeneity of thalassemia.
High performance liquid chromatography (HPLC) is a useful and rapid tool in the evaluation of hemoglobin (Hb) disorders that include thalassemia and various hemoglobinopathies. Most of the techniques or programs used in automated testing platforms are customized to identify the common variants seen in that particular region. At times, variant Hbs may be identified which are not commonly seen in the local population. This may cause diagnostic dilemma and may require further studies for definitive characterization. We present a patient with Hb Rush (HBB: c.304G>C), a rare unstable Hb variant eluting in the Hb S (HBB: c.20A>T) window on HPLC.
Hemoglobin A1c (HbA1c) is a widely utilized biomarker for the diagnosis and management of diabetes mellitus. Here, we describe an α1-globin chain hemoglobin variant and investigate its effect on HbA1c measurement. A 26-year-old pregnant woman was suspected to harbor a hemoglobin variant following HbA1c measurement during a routine prenatal examination using D10 (Bio-Rad). An oral glucose tolerance test (OGTT) was performed using an AU5800 clinical chemistry system (Beckman Coulter). HbA1c was reanalyzed using VII-T 2.0 (Bio-Rad), Capillarys 2 Flex Piercing (C2FP, HbA1c program, Sebia), Premier Hb9210 (Trinity Biotech), and Cobas c501 (Cobas Tina-quant Hemoglobin A1c Gen.3). Glycated albumin (GA) level was also quantified using an enzymic method GA Kit (Lucica GA-L, Japan). Hemoglobin analysis was performed using high performance liquid chromatography on the Bio-Rad Variant II (β-thalassemia short program) and capillary electrophoresis (Capillarys 2 Flex Piercing, Hb program). Sanger sequencing of α and β genes was also conducted. HbA1c was initially measured at 16.0% (151 mmol/mol) using the D10 (Bio-Rad). Her OGTT result was normal. Subsequently, HbA1c values determined by VII-T 2.0, C2FP, Premier Hb9210, and Cobas c501 were 4.8% (29 mmol/mol), 4.9% (30 mmol/mol), 4.6% (27 mmol/mol), and 4.8% (29 mmol/mol), respectively. The glycated albumin level was 12.3% (reference: 10.8 ∼ 17.1%). Hemoglobin analyzed using CE and HPLC revealed an abnormal hemoglobin. By Sanger sequencing, we identified a transition mutation in the α1 gene Hb Shantou [α127(H10)Lys > Glu; HBA1: c.382 A > G]. Clinically silent variants may interfere with HbA1c determination by common methods.
HbVar (http://globin.bx.psu.edu/hbvar) is one of the oldest and most appreciated locus-specific databases launched in 2001 by a multi-center academic effort to provide timely information on the genomic alterations leading to hemoglobin variants and all types of thalassemia and hemoglobinopathies. Database records include extensive phenotypic descriptions, biochemical and hematological effects, associated pathology and ethnic occurrence, accompanied by mutation frequencies and references. Here, we report updates to >600 HbVar entries, inclusion of population-specific data for 28 populations and 27 ethnic groups for α-, and β-thalassemias and additional querying options in the HbVar query page. HbVar content was also inter-connected with two other established genetic databases, namely FINDbase (http://www.findbase.org) and Leiden Open-Access Variation database (http://www.lovd.nl), which allows comparative data querying and analysis. HbVar data content has contributed to the realization of two collaborative projects to identify genomic variants that lie on different globin paralogs. Most importantly, HbVar data content has contributed to demonstrate the microattribution concept in practice. These updates significantly enriched the database content and querying potential, enhanced the database profile and data quality and broadened the inter-relation of HbVar with other databases, which should increase the already high impact of this resource to the globin and genetic database community.
Glucose-6-phosphate dehydrogenase (G6PD) deficiency is probably the most common disease-producing genetic polymorphism of humans. Virtually all G6PD-deficient Africans show the G6PD A- phenotype, an electrophoretically rapid, deficient enzyme. The recently acquired ability to identify the point mutations producing the different variants has given us new insights into the population genetics of G6PD variants. Twenty-nine males with the G6PD A- phenotype were studied. They were of African, Mexican, Spanish, and US white ethnic origin. All had the A---G transition at nucleotide 376 characteristic of G6PD A. In each case, one of three additional mutations was present, at nucleotides 202, 680, or 968. That in this population second mutations producing G6PD deficiency occurred only on the genetic background of G6PD A suggests that G6PD A was at one time the most common type of G6PD in Africa. However, the nucleotide sequence of the chimpanzee (Pan troglodytes) G6PD indicates that the primordial human type of G6PD was G6PD B.
The glutamyl residue at G3(101)beta of normal hemoglobin (Hb A) is one of the alpha 1 beta 2 subunit contacts which are vital to O2 binding properties of the molecule. The O2 equilibrium properties of the four mutants with different substitutions at this site are studied in order to elucidate the role of this residue. Under stripped conditions with minimum chloride the order of O2 affinity is: Hb A (Glu) much less than Hb Rush (Gln) less than or equal to Hb British Columbia (Lys) less than or equal to Hb Potomac (Asp) less than or equal to Hb Alberta (Gly). The first Adair constants, K1, for the mutant hemoglobins are greater than that for Hb A whereas the fourth, K4, are similar, indicating that the allosteric constants (L) of these mutants are greatly reduced. Therefore, the G3(101)beta residue contributes intrinsically to the strengthening of the structural constraints that are imposed upon the deoxy (T) forms but not the oxy (R) form. On addition of 0.1 M Cl- and further addition of 2,3-diphosphoglycerate or inositol hexaphosphate, their O2 affinities and cooperativities are altered, reflecting different responses to anionic ligands. Hb Rush exhibits a stronger chloride effect than Hb A and the other variants and, as a result, an increased Bohr effect and a smaller heat of oxygenation at pH 6.5. These changes are consistent with an increased positive net charge in the central cavity of Hb Rush and subsequent extra anion binding in the deoxy form. The tetramer to dimer dissociation constants are estimated to be greater than normal for Hb British Columbia and less than normal for Hb Alberta. This comparative study of the G3(101)beta mutants indicates that the size and the charge of this residue may influence the switching of two neighboring interchain hydrogen bonds that occurs during oxygenation of normal hemoglobin.
Blood from a woman with unexplained erythrocytosis had increased oxygen affinity, but no abnormality could be detected by electrophoresis or chromatography of her hemolysate. Separation of the tryptic peptides of her beta chains disclosed two half-sized peaks in the regions of beta T- 11. The faster of these was abnormal, with the structure beta 101 Glu replaced by Asp. The new hemoglobin was called “Potomac.” Three of the proband's four surviving siblings and both of her children were carriers. Differences in the ratio of carrier: normal children born to male of female carriers of 23 other high-affinity hemoglobins were not significant. The high proportion of carriers in this kindred was probably due to chance alone, and not because high maternal oxygen affinity interfered with oxygen transport to fetuses with normal hemoglobin.
Hb-Alberta has been found in a 51 year old Caucasian male with erythrocytosis. The substitution in this variant involves the glutamyl residue in position lOl(G3) of the β chain which is replaced by a glycyl residue. Hb-Alberta accounts for about 45% in the heterozygote, and readily forms hybrid tetramers with other hemoglobins. The oxygen affinity of Hb-Alberta is greatly increased, its Bohr effect reduced, and its subunit interaction greatly diminished. © 1976 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.
We report here on the application of the polymerase chain reaction (PCR) technique for the determination of the β-like gene cluster haplotypes. Seven fragments containing each one of the following polymorphic sites—Xmnl 5′ to the Gγ gene, Hindlll in the IVSII of Gγ and A γ gene, Hincll 3′ and inside the γ gene, Hinfl 5′ of the β gene—and Hpal 3′ of the β gene—are amplified using the PCR technique. Each amplified fragment is subsequently digested with the appropriate enzyme, analyzed by electrophoresis on agarose gel containing ethidium bromide, and visualized under ultraviolet light. This technique has the advantages of rapidity, safety, and cost-effectiveness.
Hemoglobin British Columbia was found in an East Indian living in Vancouver, British Columbia. Canada. Its structure was demonstrated to be α2β2 101(G3)Glu→Lys. It has a significant increase in oxygen affinity, decrease in heme-heme interaction, but normal Bohr effect. Unlike Hb Rush (β101 Glu→Glu), it is as stable as Hb A to heat and alcohol denaturation. By both cellulose acetate electrophoresis and chromatography the undissociated Hb British Colmbia moves between Hb S and Hb A rather than behaving like Hb C. However, the dissociated abnormal β chain behaves like βC. The substitution is at the α2β2 contact region. Except for a mild erythrocytosis, the propositus has normal hematological findings.
Sickle cell disease (SCD) and beta thalassaemia, caused by lesions that affect the HBB (beta globin gene), form the most common human genetic disorders world-wide, and represent a major public health problem. Inter-individual variation in foetal haemoglobin (HbF) expression is a known and heritable disease modifier; high HbF levels are correlated with reduced morbidity and mortality in both diseases. This review traces our progress in the understanding of the persistence of HbF in adults as a quantitative trait and the genetic approaches used in teasing out the loci contributing to its variability in normal populations and in patients with haemoglobinopathies. Three major loci -- Xmn1-HBG2 single nucleotide polymorphism, HBS1L-MYB intergenic region on chromosome 6q, and BCL11A -- contribute 20-50% of the trait variance in patients with sickle cell anaemia and healthy European Caucasians. It is likely that the remaining trait variance is due to numerous other loci, many contributing modest effects. Identification of the three major loci has not yet been translated into new therapeutic approaches for HbF reactivation but an immediate application would be an improved prediction of one's ability to produce HbF, which in turn, may improve prediction of disease severity.
Glucose-6-phosphate deficiency is the most prevalent enzyme deficiency, with an estimated 400 million people affected worldwide. This inherited deficiency causes neonatal hyperbilirubinemia and chronic hemolytic anemia. Although most affected individuals are asymptomatic, exposure to oxidative stressors such as certain drugs or infection, can elicit acute hemolysis. To characterize the global prevalence of G6PD deficiency, we conducted a systematic review of the G6PD deficiency literature, drawing studies from various databases, including MEDLINE/Pubmed and Biosis. Selected studies included cross-sectional and longitudinal studies published between 1960 and 2008. Additionally, meta-analytic procedures were employed to assess the degree of heterogeneity amongst prevalence estimates and, where appropriate, pool them. The searches yielded a total of 280 prevalence estimates, corresponding to 88 countries. The highest prevalence rates were reported among Sub-Saharan African countries, even after adjusting for assessment method. Meta-analysis revealed a high degree of heterogeneity for regional and global prevalence estimates. This heterogeneity in reported estimates appeared to be due to differences in G6PD deficiency assessment and diagnostic procedures. The magnitude and variation in global, regional, and country-level prevalence rates of G6PD deficiency are of public health import, particularly in planning programs to improve neonatal health and in the distribution of various medications, especially antimalarial drugs, as G6PD deficiency is most prevalent in malaria-endemic areas.
Blood from a woman with unexplained erythrocytosis had increased oxygen affinity, but no abnormality could be detected by electrophoresis or chromatography of her hemolysate. Separation of the tryptic peptides of her beta chains disclosed two half-sized peaks in the regions of beta T-11. The faster of these was abnormal, with the structure beta 101 Glu replaced by Asp. The new hemoglobin was called "Potomac." Three of the proband's four surviving siblings and both of her children were carriers. Differences in the ratio of carrier: normal children born to male of female carriers of 23 other high-affinity hemoglobins were not significant. The high proportion of carriers in this kindred was probably due to chance alone, and not because high maternal oxygen affinity interfered with oxygen transport to fetuses with normal hemoglobin.
Hb-Alberta has been found in a 51 year old Caucasian male with erythrocytosis. The substitution in this variant involves the glutamyl residue in position 101(G3) of the beta chain which is replaced by a glycyl residue. Hb-Alberta accounts for about 45% in the heterozygote, and readily forms hybrid tetramers with other hemoglobins. The oxygen affinity of Hb-Alberta is greatly increased, its Bohr effect reduced, and its subunit interaction greatly diminished.
Hemoglobin British Columbia was found in an East Indian living in Vancouver, British Columbia, Canada. Its structure was demonstrated to be alpha2beta2 101(G3)Glu replaced by Lys. It has a significant increase in oxygen affinity, decrease in heme-heme interaction, but normal Bohr effect. Unlike Hb Rush (beta101 Glu replaced by Glu), it is as stable as Hb A to heat and alcohol denaturation. By both cellulose acetate electrophoresis and chromatography the undissociated Hb British Columbia moves between Hb S and Hb A rather than behaving like Hb C. However, the dissociated abnormal beta chain behaves like beta C. The substitution is at the alpha2beta2 contact region. Except for a mild erythrocytosis, the propositus has normal hematological findings.
When bloods from 3,159 individuals from the United States, Iran, Ethiopia, and South Vietnam were examined for erythrocytic enzyme deficiencies with a new test utilizing the visible reduction of 2,6-dichlorophenolindophenol by glutathione, gross turbidity was observed in 81 samples. All were from Southeast Asia and 78 contained hemoglobin E. The precipitation rates of various hemoglogins in hemolysates incubated with dichlorophenolindophenol were: Hb EE greater than Hb AE greater than other hemoglobins (A, S, C, D, A2, F, O-Arabia, Rush). Hemoglobin E is an oxidatively unstable hemoglobin, possibly with weakened alpha 1 beta 1 contact; it may result in increased susceptibility to oxidative hemolysis and can be simply detected and differentiated from both Hb C and Hb O-Arabia.
woman was attributed to the presenceof an ab- presence of an uncovered positive chargs in the normal hemoglobin (Hb Rush) which migrated central cavity where normally glutamic acid in cathodically to Hb A at pH 8.0. Its structural position 101 neutralizes arginine in position abnormality was found to be in the a-chain, 104 contributing to the net neutrality in this 13101 (G3) glu -e gIn. Another electrophoretic region. This neutrality is disturbed by the sub- band atH 8.0 proved to be a hybrid tetramer stitution of glutamic acid by glutamine in Hb (AaAa ush) Hb Rush is heat unstable. A Rush. T HE DETERMINATION OF the primary structure of abnormal hemoglobins with abnormal function has been most helpful for our understanding of the normal structural conditions that maintain the hemoglobin molecule stable, soluble, and capa- ble of oxygenation and deoxygenation. Depending upon the position in the primary sequence and on the physicochemical properties of the replaced and replacing amino acid, the mutational substitution may interfere with the hydrophobic character of the interior of the molecule or may change the hydrophilic properties of the molecular surface; it may alter the strength of bonds along the interchain contacts essential for the conformational interaction between chains during oxygen exchange or may ac- tually influence heme function itself. In most unstable hemoglobin variants, one neutral residue in the interior ofthe molecule has been found to be replaced by another neutral one, but of different dimensions, and the electrophorectic mobility is usually the same as that of normal hemoglobin.' The following is a report on a new unstable hemoglobin which causes mild hemolytic anemia. The reason for the instability of this hemoglobin is most likely the substitution of a neutral amino acid residue for a negatively charged one in the region of the central cavity, thus affecting the net neutrality in this part of the molecule.
Electrophoresis of the globin chains of hemoglobin on cellulose acetate in both acidic and alkaline buffers (pH about 6 and 9) containing urea and 2 mercaptoethanol is a simple, rapid means of characterizing hemoglobins. Erythrocyte hemolysate is electrophoresed in the presence of a large amount of mercaptoethanol, which liberates heme from globin, and keeps it in solution during its rapid electrophoretic removal. Each globin chain migrates at a characteristic rate, which varies with the pH and composition of the buffer. The combined data permit differentiation, with a high degree of specificity, of some similarly charged hemoglobins. They may also be useful in assessing the effect of secondary and tertiary structure on molecular charge.
The unstable haemoglobin haemolytic anaemias result from the presence in the red cell of a structurally abnormal haemoglobin variant. There are many mutations producing unstable haemoglobins; most are single amino acid replacements that affect a few key areas of the haemoglobin structure. A wide range of haemoglobin instability is evident from in vitro studies, extending from mutants with a subclinical degree of instability to those associated with severe haemolytic disease. The characteristic feature of variants associated with haemolysis is a markedly decreased stability which is readily detectable by simple screening tests. The in vivo consequence is the precipitation of the unstable haemoglobin to give Heinz bodies which are associated with the red cell membrane and lead to premature cell destruction. The unstable haemoglobins have a greater tendency to spontaneously oxidise to methaemoglobin with subsequent formation of haemichromes and precipitation. This process is significantly accelerated by external factors such as exposure to oxidative substances and increased temperature; thus haemolytic crises are frequently associated with infections in otherwise asymptomatic carriers of unstable haemoglobins. The clinical expression of the unstable haemoglobin mutation may also be modified by proteolysis of the unstable globin chain in the bone marrow. This proteolytic mechanism can predominate in the case of extremely unstable globin chains to produce primarily a thalassaemic phenotype with little if any circulating unstable haemoglobin or evidence of haemolysis.
The molecular genetics of the α-thalassemias has been comprehensively reviewed.[1][1] Of the numerous mutations that have been described, deletions at the α-globin gene locus account for the vast majority of α-thalassemia alleles.[2][2] The most widely occurring of these are the -α3.7 and -α4.2
To characterize the molecular variation in the glucose-6-phosphate dehydrogenase gene (G6PD), 196 asymptomatic and unrelated male G6PD-deficient blood donors from Belém, an Amazonian metropolis (Brazil), were analyzed. This deficiency was detected by horizontal agarose gel electrophoresis and quantitative spectrophotometric assay for enzyme activity. The mutations were searched by PCR/RFLP, SSCP, and direct DNA sequencing. The most frequent G6PD variant was the widespread and common G6PD A- (202G --> A, 376A --> G) observed in 161 subjects (82.1%). Besides this, we found another form of G6PD A- (968T --> C, 376A --> G) in 14 (7.1%) individuals, G6PD Seattle (844G --> C) in 4.6%, G6PD Santamaria (542A --> T, 376A --> G) in 2.5%, and G6PD Tokyo (1246G --> A) in one blood donor. Four novel variants were also identified: G6PD Belém (409C --> T; Pro137His), G6PD Ananindeua (376A --> G, 871G --> A; Asn126Asp, Val291Met), G6PD Crispim with four point mutations (375G --> T, 379G --> T, 383T --> C, and 384C --> T) leading to three amino acid substitutions (Met125Ile, Ala127Ser, and Leu128Pro), and G6PD Amazonia (185C --> A; Pro62His). The reported frequencies do not reflect the real values for blood donors from Belém, since an excess of individuals with "non A-" phenotype was included in this study to enhance the probability to find rare variants. Haplotype analyses were carried out for the less common G6PD variants identified in our study using PCR/RFLP for five polymorphic sites (FokI, PvuII, PstI, BclI, NlaIII). G6PD Crispim and G6PD Amazonia variants presented the most common haplotype found in G6PD B (- - + - -). G6PD Belém presented two haplotypes (- - + + +, - + + + +) and G6PD Ananindeua was found with the + - + - + haplotype. The reported heterogeneity probably is due to the great miscegenation, characteristic of the population of the Amazonian region, besides the apparently common occurrence of recurrent mutations in the G6PD gene.
Approximately 40 beta-globin gene mutations have been identified in Thailand. The detection of these mutations is currently performed by the reverse dot blot (RDB) hybridization technique, which could detect only known mutations. We describe here the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) assay for detecting unknown mutations of the beta-globin genes.
Six PCR fragments covering the promoter, entire coding region, and intervening sequences were amplified before separation by the SSCP technique. Fifteen known mutations and two polymorphisms were analyzed by this technique in various gel mixtures and temperatures to compare their mobility shift patterns.
The clear patterns of mobility shift were demonstrated when a 10% polyacrylamide gel with 5% glycerol was used. The sensitivity was found to be 100% when electrophoreses were performed at both room temperature and 6 degrees C. This technique was then applied to screen beta-globin gene mutations in Thai families with similar profiles of abnormal hemoglobins. The distinct patterns of mobility shifts were observed in which further sequencing analysis revealed an AC insertion at codon 146, causing hemoglobin Tak.
The PCR-SSCP technique might be a useful molecular technique to minimize the requirement of direct genomic sequencing to identify beta-globin gene mutations and could be applied in several developing countries where resources are limited but genetic hemoglobin disorders are highly prevalent.
Opitz G/BBB Syndrome (OS) is a multiple congenital anomaly disorder characterized by defects along the body midline. The disease is characterized by variable expressivity of signs that include hypertelorism, cleft lip and/or palate, laryngo-tracheo-esophageal abnormalities, cardiac defects, and hypospadias. OS patients also present with mental retardation and brain anatomical abnormalities. An autosomal dominant form mapping to chromosome 22 and an X-linked form of OS are known. The gene responsible for the X-linked form of OS, MID1, codes for a member of the Tripartite Motif family of E3 ubiquitin ligases. Here we report 29 novel mutations in 29 unrelated patients of a cohort of 140 male OS cases. These mutations are found in both familial and sporadic cases. They are scattered along the entire length of the gene and are represented by missense and nonsense mutations, insertions and deletions causing frame shift mutations, and deletion of either single exons or the entire gene. The variety of the mutations found confirms that loss-of-function is the mechanism underlying the OS phenotype. Moreover, the low percentage of MID1-mutated OS patients, 47% of the familial and 13% of the sporadic cases, suggests a wider genetic heterogeneity underlying the OS phenotype.
HbVar (http://globin.bx.psu.edu/hbvar) is a locus-specific database (LSDB) developed in 2001 by a multi-center academic effort to provide timely information on the genomic sequence changes leading to hemoglobin variants and all types of thalassemia and hemoglobinopathies. Database records include extensive phenotypic descriptions, biochemical and hematological effects, associated pathology, and ethnic occurrence, accompanied by mutation frequencies and references. In addition to the regular updates to entries, we report significant advances and updates, which can be useful not only for HbVar users but also for other LSDB development and curation in general. The query page provides more functionality but in a simpler, more user-friendly format and known single nucleotide polymorphisms in the human alpha- and beta-globin loci are provided automatically. Population-specific beta-thalassemia mutation frequencies for 31 population groups have been added and/or modified and the previously reported delta- and alpha-thalassemia mutation frequency data from 10 population groups have also been incorporated. In addition, an independent flat-file database, named XPRbase (http://www.goldenhelix.org/xprbase), has been developed and linked to the main HbVar web page to provide a succinct listing of 51 experimental protocols available for globin gene mutation screening. These updates significantly augment the database profile and quality of information provided, which should increase the already high impact of the HbVar database, while its combination with the UCSC powerful genome browser and the ITHANET web portal paves the way for drawing connections of clinical importance, that is from genome to function to phenotype.
Electrophoresis of polypeptide chains In: Bonini-Domingos CR (ed) Protocols of classical laboratory methods for diagnosis of hemoglobinopathies, vol 1, 1st edn
- Bonini
- Domingos
Electrophoresis of polypeptide chains Protocols of classical labo-ratory methods for diagnosis of hemoglobinopathies
- Bonini-Domingos
- Cr
Bonini-Domingos CR (2003) Electrophoresis of polypeptide chains. In: Bonini-Domingos CR (ed) Protocols of classical labo-ratory methods for diagnosis of hemoglobinopathies, vol 1, 1st edn. Universidade Estadual Paulista-UNESP, São José do Rio Preto, pp 19–21
890 was used to perform blood tests. Genomic DNA was isolated with QIAGEN kit. β-globin gene was amplified with primers described previously
- Coulter
Coulter T-890 was used to perform blood tests. Genomic DNA was isolated with QIAGEN kit. β-globin gene was amplified with primers described previously [7]. DNA se-References
Electrophoresis of polypeptide chains
- C R Bonini-Domingos
- CR Bonini-Domingos
Bonini-Domingos CR (2003) Electrophoresis of polypeptide
chains. In: Bonini-Domingos CR (ed) Protocols of classical laboratory methods for diagnosis of hemoglobinopathies, vol 1, 1st
edn. Universidade Estadual Paulista-UNESP, São José do Rio
Preto, pp 19-21