Delta globin gene variations leading to reduction in HbA2 levels.

INTRODUCTION: Mutations in the δ-globin gene are not pathogenically relevant, but co-inheritance of δ-globin variants along with ß-globin gene defects can mask the diagnosis of ß-thalassaemia trait. METHODS: Routine haematological parameters were carried out. Molecular analysis of ß-globin gene mutations was carried out by CRDB, ARMS and DNA sequencing. δ- globin gene analysis was carried out by DNA sequencing. RESULTS: In this case study, we report a ß-thalassaemia trait (IVS 1-5G→C) (HBB:c.92 + 5G→C) with HbA2 of 1% showing the presence of δ-globin gene variant HbA2 St. George CD 81 (C→T) (HBD:c.244C→T). A similar observation was reported in another unrelated patient who showed near absence of HbA2 level in HPLC. He showed a presence of δ-globin gene mutation HbA2 Saurashtra CD 100(C→T) (HBD: c.301C→T) and a single 3.7 kb deletion in the α-globin gene. CONCLUSION: In the countries, where ß-thalassaemia is prevalent, an awareness and detection of different δ-globin gene mutations is important, as complex interactions between these haemoglobinopathies can lead to the misdiagnosis of ß-thalassaemia carriers.

ICSH recommendations for assessing automated high-performance liquid chromatography and capillary electrophoresis equipment for the quantitation of HbA2.

Automated high performance liquid chromatography and Capillary electrophoresis are used to quantitate the proportion of Hemoglobin A2 (HbA2 ) in blood samples order to enable screening and diagnosis of carriers of ß-thalassemia. Since there is only a very small difference in HbA2 levels between people who are carriers and people who are not carriers such analyses need to be both precise and accurate. This paper examines the different parameters of such equipment and discusses how they should be assessed.

Molecular understanding of Indian untransfused thalassemia intermedia.

BACKGROUND: The term thalassemia intermedia describe a form of thalassemia of intermediate severity, between the major transfusion-dependent forms of the disease and the symptomless carrier states. The phenotypic diversity of ß-thalassemia results from its underlying genetic diversity. The wide clinical variability of these conditions leads to major difficulties in their management. The molecular basis of thalassemia intermedia is very heterogeneous. The clinical and hematological course of ß-thalassemia intermedia is influenced by a number of genetic factors. METHODS AND RESULTS: The main aim of the study was to evaluate the effect of globin and nonglobin genetic modifiers on clinical severity of the disease. The study group consisted of 66 homozygous patients with ß-thalassemia [40 transfusion-dependent thalassemia (TDT), 26 nontransfusion-dependent thalassemia (NTDT)]. Hepatosplenomegaly was pronounced in the NTDT group. The presence of associated α-thalassemia was significantly higher in untransfused patients (P < 0.05). The milder ß-thalassemia mutations, such as Cap site +1 (A → C), -88 (C → T), and -87 (C → G), were observed mainly in the NTDT group (9.61%) as against patients with TDT (1.25%). The cis-DNA haplotypes, motifs, or polymorphisms around the gamma-globin genes [(AT)x (T)y motif (38.4%), XmnI (76.92%)and the Aγ-δ intergenic region haplotype T (73.07%) and Pre Gγ globin gene haplotype TAG (46.15%)] contributed significantly in amelioration of the disease severity. CONCLUSION: Our study emphasizes the complexity of genetic interactions that underlie the phenotype of ß-thalassemia and highlights the importance of epistatic factors and the regulation of HbF production in ß-thalassemia syndromes.

A successful twin pregnancy in a patient with HbE-ß-thalassemia in western India.

Improvements in medical facilities have helped a large number of clinically severe hemoglobin E (HbE)-ß-thalassemia patients reach adulthood. Consequently, there is a new challenge, that of managing women with HbE-ß-thalassemia during pregnancy. In particular, they have a high risk of abortion, preterm delivery, intrauterine growth restriction, and thromboembolism. A 27-year-old HbE-ß-thalassemia patient on regular transfusion, who was splenectomized and heptatitis C (HCV)-positive, conceived for the first time without any infertility treatment. However, there was incomplete abortion with heavy bleeding at 3 months of gestation, which required bilateral uterine artery angiography. The angiogram showed the left uterine artery to be moderately hypertrophied. This was embolized with 300-500 micron polyvinyl alcohol (PVA) to stop the bleeding. Soon after, she conceived again with a twin pregnancy, and at 33.3 weeks of gestation, there was a normal delivery of twin girls without any postpartum hemorrhage or perineal tear. Both babies were given prematurity care. The mother and children were both normal up till the last follow-up 18 months after delivery, and both the girls are HbE heterozygous. Thorough monitoring of endocrine functions along with proper management of transfusions and iron overload can help in reducing the complications related to pregnancy in these patients.

Clinical spectrum and molecular basis of recessive congenital methemoglobinemia in India.

We report the clinical features and molecular characterization of 23 patients with cyanosis due to NADH-cytochrome b5 reductase (NADH-CYB5R) deficiency from India. The patients with type I recessive congenital methemoglobinemia (RCM) presented with mild to severe cyanosis only whereas patients with type II RCM had cyanosis associated with severe neurological impairment. Thirteen mutations were identified which included 11 missense mutations causing single amino acid changes (p.Arg49Trp, p.Arg58Gln, p.Pro145Ser, p.Gly155Glu, p.Arg160Pro, p.Met177Ile, p.Met177Val, p.Ile178Thr, p.Ala179Thr, p.Thr238Met, and p.Val253Met), one stop codon mutation (p.Trp236X) and one splice-site mutation (p.Gly76Ser). Seven of these mutations (p.Arg50Trp, p.Gly155Glu, p.Arg160Pro, p.Met177Ile, p.Met177Val, p.Ile178Thr, and p.Thr238Met) were novel. Two mutations (p.Gly76Ser and p.Trp236X) were identified for the first time in the homozygous state globally causing type II RCM. We used the three-dimensional (3D) structure of human erythrocyte NADH-CYB5R to evaluate the protein structural context of the affected residues. Our data provides a rationale for the observed enzyme deficiency and contributes to a better understanding of the genotype-phenotype correlation in NADH-CYB5R deficiency.

Clinical and molecular characterization of Hb Hofu in eastern India.

INTRODUCTION: Hb Hofu (HBB:c. 380T>A) is a rare inherited hemoglobin abnormality with few case reports in the world literature. METHODS: Screening for the sickle cell gene mutation and other hemoglobinopathies was carried out using the sickle slide test, Hb electrophoresis, and HPLC under an ongoing central government project. RESULTS: We detected twelve Hb Hofu heterozygotes and three sickle Hb Hofu compound heterozygotes. The heterozygotes were asymptomatic except for one individual who had chronic kidney disease and moderate anemia. Only one HbS-Hofu case was symptomatic and presented with intermittent attacks of painful crisis. In the carrier state, the Hb Hofu eluted as a hump at the beginning of the HbA(0) window. But in HbS-Hofu cases, Hb Hofu eluted as a single peak in the HbA(0) window, with the HbA(2) levels being >4% consistently. CONCLUSION: HbS-Hofu has a variable clinical presentation. The retention time of Hb Hofu on HPLC is very close to that of HbA(0) and often elutes in the A0 window. Thus, there is every possibility of the HbS-Hofu chromatogram to be misinterpreted as that of a sickle cell trait/transfused sickle cell-beta-thalassemia case. This is the first time where Hb Hofu has been detected by HPLC, which is the widely accepted screening technique for hemoglobinopathies around the world.

Attenuation of oxidative hemolysis of human red blood cells by the natural phenolic compound, allylpyrocatechol.

The protecting ability of the Piper betle leaves-derived phenol, allylpyrocatechol (APC) against AAPH-induced membrane damage of human red blood cells (RBCs) was investigated. Compared to control, AAPH (50 mM) treatment resulted in significant hemolysis (55%, p < 0.01), associated with increased malondialdehyde (MDA) (2.9-fold, p < 0.001) and methemoglobin (6.1-fold, p < 0.001) levels. The structural deformation due to membrane damage was confirmed from scanning electron microscopy (SEM) images and Heinz bodies formation, while the cell permeability was evident from the K(+) efflux (28.7%, p < 0.05) and increased intracellular Na(+) concentration (8%, p < 0.05). The membrane damage, due to the reduction of the cholesterol/phospholipids ratio and depletion (p < 0.001) of ATP, 2,3-DPG by ˜44-54% and Na(+)-K(+) ATPase activity (43.7%), indicated loss of RBC functionality. The adverse effects of AAPH on all these biochemical parameters and the resultant oxidative hemolysis of RBCs were significantly reduced by pretreating the cells with APC (7 µM) or α-tocopherol (50 µM) for 1 h, prior to incubation with AAPH.

Detection of fetal mutations causing hemoglobinopathies by non-invasive prenatal diagnosis from maternal plasma.

BACKGROUND: Prenatal diagnosis of hemoglobinopathies enables couples at risk to have a healthy child. Currently used fetal sampling procedures are invasive with some risk of miscarriage. A non-invasive approach to obtain fetal deoxyribonucleic acid (DNA) for diagnosis would eliminate this risk. AIM: To develop and evaluate a non-invasive prenatal diagnostic approach for hemoglobinopathies using cell-free fetal DNA circulating in the maternal plasma. SETTINGS AND DESIGN: Couples referred to us for prenatal diagnosis of hemoglobinopathies where the maternal and paternal mutations were different were included in the study. MATERIALS AND METHODS: Maternal peripheral blood was collected at different periods of gestation before the invasive fetal sampling procedure was done. The blood was centrifuged to isolate the plasma and prepare DNA. A size separation approach was used to isolate fetal DNA. Nested polymerase chain reaction (PCR)-based protocols were developed for detection of the presence or absence of the paternal mutation. RESULTS AND CONCLUSIONS: There were 30 couples where the parental mutations were different. Of these, in 14 cases the paternal mutation was absent and in 16 cases it was present in the fetus. Using cell-free fetal DNA from maternal plasma, the absence of the paternal mutation was accurately determined in 12 of the 14 cases and the presence of the paternal mutation was correctly identified in 12 of the 16 cases. Thus, this non-invasive approach gave comparable results to those obtained by the conventional invasive fetal sampling methods in 24 cases giving an accuracy of 80.0%. Although the nested PCR approach enabled amplification of small quantities of cell-free DNA from maternal plasma at different periods of gestation after size separation to eliminate the more abundant maternal DNA, an accurate diagnosis of the presence or absence of the paternal mutation in the fetus was not possible in all cases to make it clinically applicable.

Prevalence of ß-thalassemia and other haemoglobinopathies in six cities in India: a multicentre study.

The population of India is extremely diverse comprising of more than 3,000 ethnic groups who still follow endogamy. Haemoglobinopathies are the commonest hereditary disorders in India and pose a major health problem. The data on the prevalence of ß-thalassemias and other haemoglobinopathies in different caste/ethnic groups of India is scarce. Therefore the present multicentre study was undertaken in six cities of six states of India (Maharashtra, Gujarat, West Bengal, Assam, Karnataka and Punjab) to determine the prevalence of haemoglobinopathies in different caste/ethnic groups using uniform methodology. Fifty-six thousand seven hundred eighty individuals (college students and pregnant women) from different caste/ethnic groups were screened. RBC indices were measured on an automated haematology counter while the percentage of HbA(2), HbF and other abnormal Hb variants were estimated by HPLC on the Variant Hemoglobin Testing System. The overall prevalence of ß-thalassemia trait was 2.78 % and varied from 1.48 to 3.64 % in different states, while the prevalence of ß-thalassemia trait in 59 ethnic groups varied from 0 to 9.3 %. HbE trait was mainly seen in Dibrugarh in Assam (23.9 %) and Kolkata in West Bengal (3.92 %). In six ethnic groups from Assam, the prevalence of HbE trait varied from 41.1 to 66.7 %. Few subjects with δß-thalassemia, HPFH, HbS trait, HbD trait, HbE homozygous and HbE ß-thalassemia as well as HbS homozygous and HbS-ß-thalassemia (<1 %) were also identified. This is the first large multicentre study covering cities from different regions of the country for screening for ß-thalassemia carriers and other haemoglobinopathies where uniform protocols and methodology was followed and quality control ensured by the co-ordinating centre. This study also shows that establishment of centres for screening for ß-thalassemia and other haemoglobinopathies is possible in medical colleges. Creating awareness, screening and counselling can be done at these centres. This experience will help to formulate a national thalassemia control programme in India.

A new simple approach for the determination of pyrimidine 5'-nucleotidase activity in human erythrocytes using an ELISA reader.

INTRODUCTION: Pyrimidine 5' nucleotidase type I (P5'N-1) deficiency is the most frequent abnormality of cell nucleotide metabolism causing hereditary non spherocytic hemolytic anemia (HNSHA). The aim of this study was to develop a simple method of determination of P5'N-1 activity in human erythrocytes using an ELISA reader METHODS: Determination of P5'N-1 activity is based on the liberation of inorganic phosphorus (Pi) after incubation with uridine monophosphate/cytidine monophosphate. Inorganic phosphorus (Pi), a product of the enzymatic reaction is directly quantitated from its ultraviolet absorbance. Purine/Pyrimidine nucleotides ratio (OD 260: OD 280) was also measured RESULTS: P5'N-1 deficient patients showed reduction in P5'N-1 activity (Mean ± SD; 4.06 ± 0.66 using an ELISA reader & 6.25 ± 1.37 using a spectrophotometer) as compared to the normal control group (ELISA reader: 13.24 ± 3.42 & Spectrophotometer: 18.25 ± 3.20). Heterozygotes showed intermediate activity (ELISA reader: 6.06 ± 0.48 & Spectrophotometer: 8.06 ± 1.28), however they would have been missed on screening using the Purine/Pyrimidine nucleotides ratio CONCLUSION: Determination of P5'N-1 activity by using an ELISA reader is a new, simple, less time consuming and reliable method. It also avoids the use of radioactive material or HPLC which is a significant advantage.

Hemoglobin Lepore Hollandia in India.

INTRODUCTION: Hb Lepore is a structurally abnormal hemoglobin in which the abnormal globin chain is a hybrid or fused 뫧 globin chain. In the heterozygous condition, Hb Lepore produces the phenotype of heterozygous ß thalassemia with slightly raised HbF levels. METHOD: Using a combination of HPLC and DNA analysis, we have identified eight individuals with Hb Lepore Hollandia from three families including seven heterozygotes and one compound heterozygote with ß thalassemia who presented with a severe clinical phenotype. RESULTS: All the heterozygotes showed elevated levels of HbF with a mean of 3.2%. Hb Lepore Hollandia genes were associated with a single ß globin cluster haplotype [- - - - - - +] indicating a common origin. CONCLUSION: Hemoglobin Lepore Hollandia is a relatively uncommon variant in the Indian population and can be identified using a combination of chromatographic, electrophoretic, and molecular analysis.

Invasive & non-invasive approaches for prenatal diagnosis of haemoglobinopathies: experiences from India.

The thalassaemias and sickle cell disease are the commonest monogenic disorders in India. There are an estimated 7500 - 12,000 babies with ß-thalassaemia major born every year in the country. While the overall prevalence of carriers in different States varies from 1.5 to 4 per cent, recent work has shown considerable variations in frequencies even within States. Thus, micromapping would help to determine the true burden of the disease. Although screening in antenatal clinics is being done at many centres, only 15-20 per cent of pregnant women register in antenatal clinics in public hospitals in the first trimester of pregnancy. There are only a handful of centres in major cities in this vast country where prenatal diagnosis is done. There is considerable molecular heterogeneity with 64 mutations identified, of which 6 to 7 common mutations account for 80-90 per cent of mutant alleles. First trimester foetal diagnosis is done by chorionic villus sampling (CVS) and DNA analysis using reverse dot blot hybridization, amplification refractory mutation system (ARMS) and DNA sequencing. Second trimester diagnosis is done by cordocentesis and foetal blood analysis on HPLC at a few centres. Our experience on prenatal diagnosis of haemoglobinopathies in 2221 pregnancies has shown that >90 per cent of couples were referred for prenatal diagnosis of ß-thalassaemia after having one or more affected children while about 35 per cent of couples were referred for prenatal diagnosis of sickle cell disorders prospectively. There is a clear need for more data from India on non-invasive approaches for prenatal diagnosis.

Five alpha globin chain variants identified during screening for haemoglobinopathies.

BACKGROUND: This study was undertaken to analyse cases of microcytosis, and/or haemolytic anaemia where an unusual peak on HPLC or an abnormal electrophoretic mobility in isolation or along with common beta-globin gene defects was found, and to identify the molecular abnormality in them. PATIENTS AND METHODS: Investigations included a complete blood count, HPLC analysis, cellulose acetate electrophoresis (pH 8.9), heat stability test and DNA sequencing. RESULTS: Five alpha chain variants were identified. This is the first report of Hb Jackson and Hb O Indonesia in the Indian population. The presence of Hb J Meerut along with Hb E and Hb J Paris I with heterozygous beta-thalassaemia are uncommon associations. Hb Sun Prairie would have remained undetected in the heterozygous state. The presence of a homozygous child in the family helped to identify this variant. CONCLUSIONS: This study emphasizes the need to undertake systematic investigations while screening for the beta haemoglobinopathies to identify rare alpha chain variants in a population.

A descriptive profile of ß-thalassaemia mutations in India, Pakistan and Sri Lanka.

Thalassaemia is a common and debilitating autosomal recessive disorder affecting many populations in South Asia. To date, efforts to create a regional profile of ß-thalassaemia mutations have largely concentrated on the populations of India. The present study updates and expands an earlier profile of ß-thalassaemia mutations in India, and incorporates comparable data from Pakistan and Sri Lanka. Despite limited data availability, clear patterns of historical and cultural population movements were observed relating to major ß-thalassaemia mutations. The current regional mutation profiles of ß-thalassaemia have been influenced by historical migrations into and from the Indian sub-continent, by the development and effects of Hindu, Buddhist, Muslim and Sikh religious traditions, and by the major mid-twentieth century population translocations that followed the Partition of India in 1947. Given the resultant genetic complexity revealed by the populations of India, Pakistan and Sri Lanka, to ensure optimum diagnostic efficiency and the delivery of appropriate care, it is important that screening and counselling programmes for ß-thalassaemia mutations recognise the underlying patterns of population sub-division throughout the region.

Evaluation of a capillary blood collection system for screening for hemoglobinopathies in remote areas.

Accurate estimation of hemoglobin (Hbs) A, Hb A(2), Hb F and abnormal Hb is required for diagnosis of hemoglobinopathies and genetic counseling. High pressure liquid chromatography (HPLC) is the most suitable approach available. But for 70% of the rural Indian population, HPLC analysis facilities are not available and screening would require transportation of samples to laboratories in bigger cities. We thus evaluated the feasibility of using a kit designed for measuring Hb A(1c) using capillary blood for collection and preservation of samples over a period of 15 days at different temperatures for screening for hemoglobinopathies. Capillary blood (5 microl) of 90 individuals was collected in the capillary collection system and run on the Variant Hemoglobin Testing System on days 1, 3, 5, 8, 12 and 15 after incubation at 4, 22, 37, 42 and 50 degrees C. The stability of different Hbs varied at different temperatures. The stability was maintained for 12 to 15 days by most of the samples up to 37 degrees C. Hb E was stable for 3 days up to at 37 degrees C and Hb D and Hb Q for 3 days up to 42 degrees C. This capillary blood collection system would have tremendous potential for sample collection and transportation under adverse climatic conditions for screening of hemoglobinopathies in remote areas in different countries.

Spectrum of novel mutations in the human PKLR gene in pyruvate kinase-deficient Indian patients with heterogeneous clinical phenotypes.

Eighteen unrelated pyruvate kinase (PK)-deficient Indian patients were identified in the past 4 years with varied clinical phenotypes ranging from a mild chronic haemolytic anaemia to a severe transfusion-dependent disorder. We identified 17 different mutations in the PKLR gene among the 36 mutated alleles. Ten novel mutations were identified: 427G>A, 499C>A, 1072G>A, 1180G>T, 1216G>A, 1220A>G, 644delG, IVS5 (+20) C>A, IVS9 (+44) C>T, and IVS9 (+93) A>C. A severe syndrome was commonly associated with some mutations, 992A>G, 1436G>A, 1220A>G, 644delG and IVS9 (+93) A>C, in the PKLR gene. Molecular graphics analysis of human red blood cell PK (RPK), based on the crystal structure of human PK, shows that mutations located near the substrate or fructose 1,6-diphosphate binding site may change the conformation of the active site, resulting in very low PK activity and severe clinical symptoms. The mutations target distinct regions of RPK structure, including domain interfaces and catalytic and allosteric sites. In particular, the 1216G>A and 1219G>A mutations significantly affect the interdomain interaction because they are located near the catalytic site in the A/B interface domains. The most frequent mutations in the Indian population appear to be 1436G>A (19.44%), followed by 1456C>T (16.66%) and 992A>G (16.66%). This is the first study to correlate the clinical profile with the molecular defects causing PK deficiency from India where 10 novel mutations that produce non-spherocytic haemolytic anaemia were identified.

Microsatellite diversity among the primitive tribes of India.

The present study was undertaken to determine the extent of diversity at 12 microsatellite short tandem repeat (STR) loci in seven primitive tribal populations of India with diverse linguistic and geographic backgrounds. DNA samples of 160 unrelated individuals were analyzed for 12 STR loci by multiplex polymerase chain reaction (PCR). Gene diversity analysis suggested that the average heterozygosity was uniformly high ( >0.7) in these groups and varied from 0.705 to 0.794. The Hardy-Weinberg equilibrium analysis revealed that these populations were in genetic equilibrium at almost all the loci. The overall G(ST) value was high (G(ST) = 0.051; range between 0.026 and 0.098 among the loci), reflecting the degree of differentiation/heterogeneity of seven populations studied for these loci. The cluster analysis and multidimensional scaling of genetic distances reveal two broad clusters of populations, besides Moolu Kurumba maintaining their distinct genetic identity vis-à-vis other populations. The genetic affinity for the three tribes of the Indo-European family could be explained based on geography and Language but not for the four Dravidian tribes as reflected by the NJT and MDS plots. For the overall data, the insignificant MANTEL correlations between genetic, linguistic and geographic distances suggest that the genetic variation among these tribes is not patterned along geographic and/or linguistic lines.