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Abstract: Introduction: Rheumatoid arthritis (RA) is a clinically heterogeneous chronic inflammatory disorder characterized by synovitis leading to joint destruction. Both genetic and environmental factors are involved in the pathogenesis of RA. Significant dysregulation of NKG2D, an activating receptor of natural killer and certain autoreactive T cells as well as its ligand major histocompatibility complex class I chain–related gene A (MICA) has been implicated in perpetuating the pathology of RA. Since the genetic polymorphism in MICA gene (MICA‐129 met/val polymorphism at codon 129) is known to affect its binding affinity to NKG2D, we explored its influence on RA susceptibility and disease severity. Methods: The MICA‐129 met/val polymorphism was examined in 270 patients with RA and 232 healthy controls by TaqMan 5′‐nuclease assay. Serum soluble MICA (sMICA) was measured in a subset of 89 patients and 80 controls by enzyme‐linked immunosorbent assay. Results: We observed that the frequency of MICA‐129 val allele (73% vs. 65%, Pc = 0.006, odds ratio = 1.48, 95% CI = 1.12–1.95) was higher in patients than in controls. sMICA levels were significantly higher in patients with RA than in controls (P < 0.0001). sMICA levels were higher in patients with val/val genotype than in those with met/val or met/met genotype (P = 0.03). The MICA‐129 val/val genotype was associated with high titers of sMICA in patients with deforming RA phenotype (P = 0.02), suggesting a role in determination of severity of RA. Conclusion: MICA‐129 val/val genotype, associated with higher levels of circulating sMICA, may influence disease susceptibility and associate with increased severity of RA in south Indian Tamils. [ABSTRACT FROM AUTHOR]

Introduction Coinheritance of α-thalassemia influences the clinical and hematological phenotypes of β-hemoglobinopathies (β-thalassemia and sickle cell disease) and when present together in significant frequency within a population, a spectrum of clinical forms is observed. Precise molecular characterization of α-thalassemia is important in understanding their disease-modifying role in β-hemoglobinopathies and for diagnostic purposes. Patients and methods Because currently used approaches are labor/cost-intensive, time-consuming, error-prone in certain genotype combinations and not applicable for large epidemiological screening, we developed a systematic stepwise strategy to overcome these difficulties. We successfully applied this to characterize the α-globin gene status in 150 Omani cord blood samples with Hb Barts and 32 patients with HbH disease. Results We observed a good correlation between α-globin genotypes and level of Hb Bart's with the Hb Bart's levels significantly higher in both deletional and non-deletional α-globin genotypes. The most common α-globin genotype in Hb H cases was α TSaudiα/α TSaudiα ( n = 16; 50%) followed by −α3.7/- MED ( n = 10; 31%). This approach detects also the α-globin gene triplication as exemplified by the study of a family where the β-globin gene defect failed to explain the β-thalassemia intermedia phenotype. Conclusion Molecular characterization of α-thalassemia is complex due to high sequence homology between the duplicated α-globin genes and to the existence of a variety of gene rearrangements (small and large deletions of various sizes) and punctual substitutions (non-deletional alleles). The novelty of our strategy resides, not in the individual technical steps per se but in the reasoned sequential order of their use taking into consideration the hematological phenotype as well. [ABSTRACT FROM AUTHOR]

Two genome-wide association studies (GWASs) recently highlighted the HLA-DRA and HLA-DRB5 genes as associated with Parkinson disease (PD). However, because HLA-DRA displays a low level of polymorphisms and HLA-DRB5 is only present in approximately 20% of the population, these findings are difficult to interpret. Our aims were: (1) to replicate and investigate in greater detail the association between PD and the HLA-DR region; (2) to identify PD-associated HLA alleles; and (3) to perform a meta-analysis of our top finding. As part of 2 French population-based case-control studies of PD including highly ethnically homogeneous participants, we investigated the association between PD and 51 Single-nucleotide polymorphisms (SNPs) in the HLA-DR region. HLA-DRB1 alleles were imputed using the HLA*IMP software. HLA typing was performed in a subsample of the participants. We performed a meta-analysis of our top finding based on 4 GWAS data sets. Among 499 cases and 1123 controls, after correction for multiple testing, we found an association with rs660895 (OR/minor allele, 0.70; 95% CI, 0.57-0.87) within the HLA-DRB1 gene, which encodes the most polymorphic HLA-DR chain (DRβ). A meta-analysis (7996 cases, 36455 controls) confirmed this association (OR, 0.86; 95% CI, 0.82-0.91; P < .0001). SNP-based imputation of HLA alleles showed an inverse association between PD and the HLA-DRB1*04 allele. We replicated an association between PD and the HLA-DR region and provided further insight into the loci and alleles involved. The highly polymorphic HLA-DRB1 locus contains rs660895, which represents a more legitimate candidate than previous ones. Our finding is in agreement with the hypothesis of an immune component in PD pathophysiology. © 2012 Movement Disorder Society [ABSTRACT FROM AUTHOR]

A novel β-globin gene promoter (−71 C>T) nucleotide change was recently posted to the HbVar database (ID 2701) without precision on phenotype and ethnicity. We found the same change in compound heterozygosity with Hb S [β6(A3)Glu>Val] in an Omani family with almost equal expression of Hb A and Hb S. This suggested that the −71 C to T mutation may be a mild β-thalassemic allele. Subsequent search found three other independent cases with the same atypical Hb A:Hb S ratio, further confirming the mild thalassemic feature of this mutation. In addition, molecular screening of a set of subjects (with only Hb A) with borderline Hb A2 or MCV values revealed the presence of −71 C>T change in heterozygous state, altogether assigning the mutation as a mild β+ thalassemic allele. In a region such as Oman, where several genetic conditions of the red blood cell coexist (α- and β-thalassemia, Hb S, Hb D, Hb E) in significant frequencies, it is crucial to decipher the molecular basis of these atypical forms of β+ thalassemias, especially in a genetic counseling setting. [ABSTRACT FROM AUTHOR]

In an Omani family, four different alpha thalassemic alleles, one single-gene deletional (−α) and three non-deletional forms (α, α, and α), interact in various combinations and result in two distinct hematological phenotypes, with and without HbH inclusions. After excluding the presence of potential genetic modifiers, viz associated β-thalassemic alleles or functional alpha hemoglobin stabilizing protein (AHSP) polymorphisms, we observed that only the genetic combinations involving α mutation are associated with HbH inclusions (a marker of degree of α/β-chain imbalance) and high reticulocyte count (a marker of ongoing hemolysis). Overall, the α mutation is associated with a more severe α-globin deficiency than the other two (α and α) non-deletional α thalassemic mutations. The likely molecular explanation is that the compensatory increase in the linked α1 globin gene expression is much more compromised in cases with α mutation. [ABSTRACT FROM AUTHOR]

Busulfan-mediated endothelial damage is believed to be a common mechanism in a variety of vascular disorders that occur during haematopoietic stem cell transplantation. The alkylating capacity of busulfan is compromised in vivo by enzymatic conjugation with glutathione, principally catalysed by glutathione S-transferase alpha (GST alpha). We investigated whether the susceptibility of endothelial cells to busulfan-mediated damage is related to their intrinsic deficiency in GST alpha expression. We tested for the expression of GST alpha mRNA by real-time quantitative PCR and the GST protein by enzyme-linked immunosorbent assay in various independently derived endothelial cell types (human bone marrow-derived endothelial cell line and endothelial cells from human vein umbilical cord ) and in a control hepatic cell line, HepG2. We demonstrate that endothelial cells, contrary to hepatic cells do not express GST alpha either at mRNA or protein levels and hence are potentially susceptible to busulfan-mediated cytotoxic damage. [ABSTRACT FROM AUTHOR]

Hb Dhofar is a variant haemoglobin (β29 (GGC–GGT) gly-gly, β58 (CCT–CGT) pro-arg) associated with a thalassaemic phenotype and unique to the Sultanate of Oman. We report clinical and haematological data on 54 subjects with Hb Dhofar (37 heterozygotes, 14 homozygotes and three compound heterozygotes with a different β-thalassaemia mutation). In heterozygotes, the level of Hb Dhofar ranged from 8.8% to 21.5%. All heterozygotes had Hb A2 > 3.5%, consistent with β-thalassaemia trait. Hb Dhofar in homozygotes and compound heterozygotes ranged from 26% to 59.7%, with a peripheral film consistent with homozygous β-thalassaemia. Age at presentation in homozygotes ranged between 6 months and 8 yr, with a majority presenting before 5 yr of age. All had splenomegaly and six (43%) had undergone splenectomy. All had some degree of frontal bossing and in particular, two patients with infrequent transfusions had marked thalassaemic facies and stunting of growth. Hb Dhofar can be mistaken for Hb D as the electrophoretic mobility is similar, but differs from it by a variable and reduced quantity of variant Hb in both heterozygotes and homozygotes. Clinical and haematological data suggest that this mutation behaves like a moderately severe β+ thalassaemia allele resulting in a thalassaemia intermedia phenotype. [ABSTRACT FROM AUTHOR]

To test the hypothesis that HbOARAB induces an increase in red cell mean corpuscular haemoglobin concentration (MCHC), we studied members of four Tunisian families who were either homo- or heterozygous for HbOARAB or were double heterozygotes for HbS and HbOARAB. The α-gene status was also tested. The findings included: (1) Distinctive variation in red cell density (MCHC) as determined by separation of red cells on isopycnic gradients: (a) All red cells from patients homozygous for HbOARAB were denser than normal red cells, as is observed for homozygous HbC patients. (b) In patients heterozygous for HbOARAB, red cell density was strongly influenced by the presence of α-thalassaemia. The coexistence of -α/αα resulted in an average red cell density slightly greater than normal (AA) red cells. Patients heterozygous for HbOARAB with a normal complement of four α genes had denser red cells similar to sickle cell disease with some cells of normal density but with most cells very dense. (c) Finally, the double heterozygotes for HbS and HbOARAB had significant haemolytic anaemia and red cells denser than normal with some as dense as the densest cells found in sickle cell anaemia. (2) Reticulocytes in patients homozygous for HbOARAB were found in the densest density fraction of whole blood. (3) Cation transport in patients homozygous for HbOARAB was abnormal, with K:Cl cotransport activity similar to that of HbS-Oman and only somewhat lower than in sickle cell anaemia red cells. The activity of the Gardos channel was indistinguishable from that found in HbS, HbC and HbS-Oman cells. We conclude that the erythrocytic pathogenesis of HbOARAB involves the dehydration of red cells due, at least in part, to the K:Cl cotransport system. The similarity of the charge and consequences of the presence of both HbC and HbOARAB, which... [ABSTRACT FROM AUTHOR]

Direct evidence is given for the presence of glucose, mannose and galactose as the products of hydrolysis of hemoglobins A1a1. A1a2, A1b, A1c and A0. The presence of galactose cannot be explained by the earlier hypothesis of Amadori rearrangement and suggests the existence of further complex rearrangements. Monosaccharide content of the different hemoglobin components varies from 0.2-2.0mol/mol of αβdimer with an increase of 1.5-2.0-times in diabetic components. This increase is not accompanied by net charge differences, suggesting that additionally bound sugars are not responsible for the p1 modification of these hemoglobins. The pattern of glucose. mannose and galactose ratio in normal individuals divides these hemoglobins into two classes. hemoglobins A1b. A1c and A0 (ratio 0.60:0.25 :0.15) on one hand and hemoglobins A1a1 and A1a2 (ratio 0.40: 0.40 :0.20) on the other. These findings suggest that diverse mechanisms for sugar binding might exist between these two classes of glycosylated hemoglobins. This difference disappears in diabetic components suggesting that the non-N 112-terminal sites are glycosytated in all components by a common mechanism. Increase in glucose at the expense of mannose and galactose. as observed in diabetics, could be an indicator of recent glycosylation. [ABSTRACT FROM AUTHOR]

We have analysed the chromatin features of DNA regions encompassing human ∊, Gy, Ay, 6 and ft globin structural genes in fetal and adult erythroid cells on the one hand and adult lymphocytes on the other. Highly purified nuclei from these cells were submitted to DNase I digestion and the kinetic data were obtained from the percentage of residual hybridization of defined regions in Southern blots. Our results, as others have shown by different approaches. indicate that the structural genes of the β-globin cluster are generally more sensitive to ONase 1 in the erythroid cells than in non-erythroid cells. Thus a domain of DNase I sensitivity related to the committed state is defined. In addition we show that within this DNase-I-sensitive β cluster domain, individual genes of the cluster are arranged in subdomains of differential DNase I sensitivity, which correlate with their expression status. Furthermore the differential expression of the two fetal genes in the fetal stage is shown to be directly proportional to the degree of hypomethylation of these genes. [ABSTRACT FROM AUTHOR]

Enhanced erythrocyte destruction in sickle cell anemia results in chronic hyperbilirubinemia. Only a subset of patients develop cholelithiasis. UGT1A1 promoter polymorphism is associated both with unconjugated bilirubin level and elevated risk for cholelithiasis in such subset. Here, we investigated the role of alpha-thalassemia, yet another genetic factor that modulates hemolysis, in conferring protection from cholelithiasis. We show that, although alpha-thalassemia is associated with modest reduction in hemolysis and unconjugated bilirubin level, UGT1A1 polymorphism outweighs its effect on cholethiogenesis in sickle cell anemia patients., (2006 Wiley-Liss, Inc.)

Familial hemophagocytic lymphohistiocytosis is an autosomal recessive disease of early childhood manifested by hypercytokinemia and organ infiltration of macrophages and activated lymphocytes, and it is characterized by a fulminant clinical course. The molecular mechanism underlying this disease appears to be a deregulation of apoptosis of activated T cells and macrophages. Approximately 20-40% of patients with familial hemophagocytic lymphohistiocytosis reported worldwide had a perforin gene mutation. We report herein a novel perforin variant in the homozygous state in an Omani boy who was diagnosed 44 days after birth. Sequence analysis of the perforin gene coding region revealed a 12-base pair deletion (codon 284-287) resulting in the deletion of four amino acids in the membrane attack complex domain of the protein. This deletion maintains the reading frame of the perforin mRNA. Both parents were heterozygotes for this molecular defect. Flow-cytometric analysis revealed intracellular perforin expression at the lower end of the normal range in the cytotoxic T cells (CD3+/CD8+) and (CD3+/CD56+) and in around 50% of the natural killer cells (CD3-/CD56+). This is an additional example of a perforin variant which is associated with a significant level of cellular perforin expression and thus confirms that drastic reduction in its expression is not a constant feature in familial hemophagocytic lymphohistiocytosis type 2.