Divergence in phenotyping and genotyping analysis of the Lewis histo-blood group system.

OBJECTIVES: This study evaluated the red blood cell (RBC) Lewis phenotypes by simple haemagglutination technique and molecular genotyping in healthy individuals. BACKGROUND: The expression of Lewis antigen on RBCs is dependent on the interaction of FUT3 and FUT2 genes. Complexity of the genetic control of Lewis antigen expression and the error-prone nature of Lewis phenotyping result in non-genuine RBC Lewis phenotypes, which could be misleading. MATERIALS AND METHODS: ABO blood group and RBC Lewis phenotypes were determined by conventional haemagglutination tube techniques. FUT2 and FUT3 genotypes were analysed by polymerase chain reaction and direct DNA sequencing. The RBC Lewis phenotypes were also inferred from the FUT2 and FUT3 genotyping results. RESULTS: The frequencies of RBC Lewis phenotypes typed by the conventional tube test were Le(a+b-) 19.63%, Le(a-b+) 49.32% and Le(a-b-) 31.05%, whereas the frequencies inferred from the FUT2 and FUT3 genotypes were Le(a+b-) 20.09%, Le(a-b+), 59.82%; Le(a-b-), 17.81%; and Le(a+b+), 5 (2.28%). The Le(a+b+) phenotype was not detected by the tube test, and a significant difference was observed in the frequencies of the determined Le(a-b-) and Le(a-b+) phenotypes. CONCLUSION: The phenotyping and genotyping of Lewis blood group system reveal a high rate of discordance in the frequencies of Lewis phenotypes among the healthy individuals.

The Changing Trends in Prenatal Diagnosis of Hemoglobinopathies in India: The Quest of a Single Center to Reduce the Burden of Disease over Three Decades.

The ß-thalassemias and sickle cell disorders pose a considerable health burden in India. Of the more than 10,000 annual births of children with a severe hemoglobinopathy, only around 10.0% are managed optimally. Thus, genetic counseling and prenatal diagnosis (PND) is a valid option for a large and diverse country. Our center was one of the first to initiate PND and we present our experience over 30 years to evaluate the impact of awareness in changing the trends of PND of hemoglobinopathies. Both second and first-trimester diagnoses were undertaken by fetoscopy/cordocentesis and globin biosynthesis/high-performance liquid chromatography (HPLC) analysis of fetal blood and chorionic villus sampling (CVS) and DNA analysis. Over 30 years, 3478 couples (first trimester: 2475; second trimester: 1003) from all over India were offered PND. The number of couples coming in the first trimester increased significantly over each decade and couples coming prospectively increased from 2.5 to 18.4%. A cost-effective stepwise approach was used for molecular analysis. Eight hundred and one fetuses (23.0%) were affected and all except three couples opted for termination of these pregnancies. Genetic counseling and PND is the only way to reduce the burden of disease. With awareness, there was a shift from second trimester to first trimester PND over each decade, with an increasing number of couples coming during the first pregnancy. There are only 15 to 20 centers in India offering PND. We have compared our study with other reports on PND from different regions in India.

Fabrication of gelatin functionalized silver nanoparticles for blood group profiling.

We report the fabrication of silver nanoparticles (AgNPs) surface functionalized with gelatin at different concentrations (G10/G20/G40 AgNPs) with an average particle size of ∼200 nm, bioconjugated with antisera antibodies (AsAbs) of the major and clinically significant blood groups (CSBGs) at different titres from neat to 1:128. Bioconjugation using ionic interaction at pH 7.4 enabled 'end-on' configuration, with the -NH2 group of the antibody free for interaction with the red blood cell antigen, as confirmed by Fourier transform infrared spectroscopy. The tube agglutination test (TAT) revealed optimum agglutination with G20NPs, while SDS PAGE confirmed the optimal titre as 1:8 for the major blood groups A, B, AB and O. Bioconjugated AgNPs coated onto microtitre assay plates with the major blood groups and CSBGs to enable simultaneous identification, were validated against the TAT on 400 random blood samples for the major blood groups and revealed high accuracy (95%). While similar accuracy was seen for most of the CSBGs with only false negatives, the method was not found to be suitable for the Kell, Kidd and Duffy groups. The absence of false positives reflects high safety, and eliminates the risk of a mismatched blood transfusion. The method uses diluted blood and hence could enable point-of-care detection. The significantly lower AsAb requirement also provides a cost advantage.

Rare ß- and δ-Globin Gene Mutations in the Pathare Prabhus: Original Inhabitants of Mumbai, India.

Genetic structure of the Indian population is influenced by waves of several immigrants from West Eurasia. Therefore, genetic information of various ethnic groups is valuable to understand their origins, the pattern of migration as well as the genetic relationship between them. No genetic data is available on Pathare Prabhu, which is a small indigenous Hindu community from Mumbai, Maharashtra State, India. The aim of this study was to screen the Pathare Prabhus for hemoglobinopathies, which is a major public health problem in India. Two hundred and fifty-seven unrelated Pathare Prabhus subjects were screened for various hemoglobinopathies. Complete blood counts (CBC) were done on an automated hematology counter. High performance liquid chromatography (HPLC) was used to identify ß-thalassemia (ß-thal) carriers. Molecular characterization of the ß gene defects was done by reverse dot-blot hybridization, amplification refractory mutation system (ARMS) and DNA sequencing. Deletional α-thalassemia (α-thal) was detected by multiplex polymerase chain reaction (PCR). Hb A2-Saurashtra (HBD: c.301C>T) was identified by DNA sequencing; its modeling was also done. The prevalence of ß-thal was 3.89%, while deletional α-thal was 5.4%. The initiation codon (ATG>ACG) (HBB: c.2T>C) was seen in eight individuals (80.0%), Hb D-Punjab (HBB: c.364G>C) and Hb A2-Saurashtra, was found in two and one individual, respectively. A community-specific ß-thal mutation was found in Pathare Prabhus in significant proportions. This information is useful in developing an algorithm for a prenatal diagnosis (PND) program.

Molecular characterization of weaker variants of A and B in Indian population--the first report.

BACKGROUND AND OBJECTIVES: The ABO blood group system is extremely important blood group system in transfusion medicine and weaker variants of A and B are subgroups of the system. From a Country like India with 1.2 billion population sporadic reports detecting weaker variants of A and B serologically are published. Therefore the main objective of the present study is to identify weaker variants of A and B serologically and characterize them at molecular level. MATERIALS AND METHODS: Eight samples which were referred to us for resolving discrepancies in forward and reverse grouping were first phenotype in our laboratory by standard serologic techniques for ABO blood groups. Molecular genotyping for the ABO locus was done by PCR-SSCP. Altered SSCP patterns were analysed by DNA sequencing. Sequencing of intron 6 and exons 1-5 was done in one sample each. RESULTS AND CONCLUSION: Nine rare alleles affecting the normal expression of A and B antigens have been identified among Indians. They were two Aw06, one A209, one Ax20, two O05, one O49, one O56 and one O19 alleles. This is the first report demonstrating molecular studies on weaker variants of A and B from India.

Molecular genotyping of ABO blood groups in some population groups from India.

BACKGROUND & OBJECTIVES: Indian population is characterized by the presence of various castes and tribal groups. Various genetic polymorphisms have been used to differentiate among these groups. Amongst these, the ABO blood group system has been extensively studied. There is no information on molecular genotyping of ABO blood groups from India. Therefore, the main objective of this study was to characterize the common A, B and O alleles by molecular analysis in some Indian population groups. METHODS: One hundred samples from the mixed population from Mumbai, 101 samples from the Dhodia tribe and 100 samples from the Parsi community were included in this study. Initially, the samples were phenotyped by standard serologic techniques. PCR followed by single strand conformational polymorphsim (SSCP) was used for molecular ABO genotyping. Samples showing atypical SSCP patterns were further analysed by DNA sequencing to characterize rare alleles. RESULTS: Seven common ABO alleles with 19 different genotypes were found in the mixed population. The Dhodias showed 12 different ABO genotypes and the Parsis revealed 15 different ABO genotypes with six common ABO alleles identified in each of them. Two rare alleles were also identified. INTERPRETATION & CONCLUSIONS: This study reports the distribution of molecular genotypes of ABO alleles among some population groups from India. Considering the extremely heterogeneous nature of the Indian population, in terms of various genotype markers like blood groups, red cell enzymes, etc., many more ABO alleles are likely to be encountered.

Interaction of iron deficiency anemia and hemoglobinopathies among college students and pregnant women: a multi center evaluation in India.

Although iron deficiency anemia is very common in India, systematic large studies on the prevalence and hematological consequences of iron deficiency among carriers of ß-thalassemia (ß-thal) and other hemoglobinopathies are lacking. A multi center project was undertaken to screen college/university students and pregnant women for iron deficiency anemia and various hemoglobinopathies. Fifty-six thousand, seven hundred and seventy-two subjects from six states, Maharashtra, Gujarat, Karnataka, West Bengal, Assam and Punjab, were studied. Iron deficiency anemia was evaluated by measuring zinc protoporphyrin (ZPP) and hemoglobin (Hb) levels, while ß-thal and other hemoglobinopathies were detected by measuring the red cell indices and by Hb analysis using high performance liquid chromatography (HPLC). College boys (2.2%), college girls (14.3%) and antenatal women (27.0%) without any hemoglobinopathies had iron deficiency anemia. Among the ß-thal carriers, the prevalence of iron deficiency anemia was 17.3% in college boys, 38.1% in college girls and 55.9% in pregnant women, while in the Hb E [ß26(B8)Glu→Lys; HBB: c.79G>A] carriers, it was 7.3% in college boys, 25.4% in college girls and 78.0% in antenatal women. In individuals with Hb E disease, the prevalence of iron deficiency anemia varied from 31.2-77.3% in the three groups. A significant reduction in Hb levels was seen when iron deficiency anemia was associated with hemoglobinopathies. However, the Hb A2 levels in ß-thal carriers were not greatly reduced in the presence of iron deficiency anemia.

Clinical, hematologic and molecular variability of sickle cell-ß thalassemia in western India.

BACKGROUND: Sickle cell-ß thalassemia (HbS-ß thalassemia) is a sickling disorder of varying severity, which results from compound heterozygosity for sickle cell trait and ß thalassemia trait. The present study was undertaken to determine the genetic factors responsible for the clinical variability of HbS-ß thalassemia patients from western India. MATERIALS AND METHODS: Twenty-one HbS-ß thalassemia cases with variable clinical manifestations were investigated. The α and ß globin gene clusters were studied by molecular analysis. RESULTS: Thirteen patients showed milder clinical presentation as against eight patients who had severe clinical manifestations. Four ß thalassemia mutations were identified: IVS 1-5 (G→C), codon 15 (G→A), codon 30 (G→C) and codon 8/9 (+G). α thalassemia and XmnI polymorphism in homozygous condition (+/+) were found to be common among the milder cases. The ß(S) chromosomes were linked to the typical Arab-Indian haplotype (#31). Framework (FW) linkage studies showed that four ß thalassemia mutations were associated with different ß globin gene frameworks. Linkage of codon 15 (G→A) mutation to FW2 is being observed for the first time. CONCLUSION: The phenotypic expression of HbS-ß thalassemia is not uniformly mild and α thalassemia and XmnI polymorphism in homozygous condition (+/+) are additional genetic factors modulating the severity of the disease in the Indian subcontinent.

The phenotypic and molecular diversity of hemoglobinopathies in India: A review of 15 years at a referral center.

INTRODUCTION: The hemoglobinopathies pose a significant health burden in India. Apart from the ß thalassemias and sickle cell disorders, α thalassemias and structural hemoglobin variants are also common. Here we have reviewed the phenotypic and molecular diversity of hemoglobinopathies encountered at a referral center in western India over a period of 15 years. MATERIALS AND METHODS: Screening for hemoglobinopathies was done using HPLC and cellulose acetate electrophoresis. Molecular characterization was done using Covalent Reverse Dot Blot Hybridization (CRDB), Amplification Refractory Mutation System (ARMS), GAP PCR and direct DNA sequencing. RESULTS: The study includes 31 075 individuals who were referred for diagnosis of hemoglobinopathies and prenatal diagnosis. Of these 14 423 individuals showed various hemoglobin abnormalities. Beta genotyping in 5615 individuals showed the presence of 49 ß thalassemia mutations. 143 ß thalassemia heterozygotes had normal or borderline HbA2 levels. We identified three δ gene mutations (HbA2 Pellendri, HbA2 St.George, HbA2 Saurashtra) in ß thalassemia heterozygotes leading to normal HbA2 levels. The commonest defects among the raised Hb F determinants were Gγ(Αγδß)0 Indian inversion and the HPFH-3 Indian deletion. A total of 312 individuals showed the presence of α thalassemia, of which 12.0% had a single α gene deletion (-α/αα). HbH disease was identified in 29 cases with 10 different genotypes. Alpha globin gene triplication was seen in 2.1% of ß thalassemia heterozygotes with a thalassemia intermedia phenotype. Seven unusual α chain variants and eight uncommon ß chain variants were identified. CONCLUSION: The repertoire of molecular defects seen in the different globin genes will be valuable for management and control of these disorders both in India as well as in other countries where there is a huge influx of migrant populations from India.

Use of lectins in immunohematology.

Lectins are carbohydrate binding proteins present in seeds of many plants, especially corals and beans, in fungi and bacteria, and in animals. Apart from their hemagglutinating property, a wide range of functions have been attributed to them. Their importance in the area of immunohematology is immense. They are used to detect specific red cell antigens, to activate different types of lymphocytes, in order to resolve problems related to polyagglutination and so on. The introduction of advanced biotechnological tools generates new opportunities to exploit the properties of lectins, which were not used earlier. Stem cell research is a very important area in transplant medicine. Certain lectins detect surface markers of stem cell. Hence, they are used to understand the developmental biology of stem cells. The role of various lectins in the areas of transfusion and transplant medicine is discussed in detail in this review.

Congenital methemoglobinemia caused by Hb-MRatnagiri (beta-63CAT-->TAT, His-->Tyr) in an Indian family.

Hb-M is a very rare hemoglobinopathy in the Indian subcontinent. We report a family with Hb-M with lifelong cyanosis from the Ratnagiri district in western India. The propositus was a 11-year-old female child with a history of increasing cyanosis exacerbated by fever and weakness. Similar complaints were also noted in her mother and five maternal family members. There was no history of cardiac illness or exposure to drugs and chemicals. The methemoglobin level was 39.3% in the propositus and 21.1% in her mother with normal NADH-methemoglobin reductase activity. Abnormal absorption peaks by spectroscopic analysis, presence of hemoglobin instability, and a slow-moving band on starch gel electrophoresis supported the presence of Hb-M. Automated DNA sequence analysis of the beta globin gene showed a C-->T substitution at codon 63. This leads to a substitution of histidine (CAT) by tyrosine (TAT) at the beta 63 (E7) position, similar to Hb-M Saskatoon. We have named this variant as Hb-M(Ratnagiri).

Detection of rare beta-thalassemia mutations by denaturing gradient gel electrophoresis among Indians.

We report four rare beta-thalassemia (thal) mutations, viz. AATAAA --> AACAAA [polyadenylation (poly A) site mutation]. IVS-II-745 (C --> G), codon 121 (G --> T) and IVS-II-1 (G --> A), detected by denaturing gradient gel electrophoresis (DGGE) among Indians. Of these, the poly A site mutation has been found in combination with deletional delta(beta)-thal in one case, and with the IVS-1-5 (G --> C) mutation in another. Two DGGE patterns, corresponding to the same IVS-II-1 (G --> A) mutation, were seen in one family. Framework (FW) analyses in family studies have shown that the poly A site mutation is associated with FW-1, while both the codon 121 (G --> T) and IVS-II-1 (G --> A) mutations are associated with FW-2. Denaturing gradient gel electrophoresis facilitates the screening of rare beta-thal mutations in the diverse Indian population with its many ethnic groups, covering a vast geographic territory.

Prenatal diagnosis in a family at risk for beta-thalassemia and hemophilia A: an uncommon association.

beta-Thalassemia (thal) is an autosomal recessive disorder with a prevalence of 2-3% in Indians, while hemophilia A is X-linked with a prevalence of 1 in 5,000-10,000 male births. The chances of both these disorders being present together is extremely rare (1 in 250,000). We report an interesting consanguineous family from Western India with a combination of these two disorders, which was referred to us for prenatal diagnosis.

Usefulness of automated chromatography for rapid fetal blood analysis for second trimester prenatal diagnosis of beta-thalassemia.

Prenatal diagnosis of beta-thalassemia is now ideally done in the first trimester of pregnancy by chorionic villus tissue DNA analysis. Nevertheless, fetal blood analysis in the second trimester is required either when the mutation in both parents cannot be characterised or when the couple comes late for investigations. We evaluated the usefulness of analysis of fetal blood on the Biorad Variant Hemoglobin Testing System using the beta-thalassemia short programme in comparison with the conventional globin biosynthesis in 58 pregnancies. The beta/alpha biosynthesis ratios in 13 homozygous fetuses ranged from 0 to 0.03 and the adult hemoglobin (HbA) levels by automated chromatography varied from 0% to 0.4%. The normal or heterozygous fetuses had beta/alpha ratios of >0.04 and HbA levels ranging from 2.1% to 10.6%. In 17 fetuses we also correlated the beta gene mutations with the predicted genotypes using automated high-performance liquid chromatography (HPLC). Follow-up of 18 unaffected fetuses using the Variant System at birth showed a significant increase in HbA levels.