Identification of a Novel Variant c.163delG in HBB Gene Resulting in a Beta Null Phenotype in a Proband with Thalassemia Intermedia.

A 21-year-old patient presented with a previous medical history of pallor, mild icterus, increased fatigue, low hemoglobin, and abnormal hemoglobin variant analysis with more than 70 transfusions. He was referred for genetic analysis to identify the pathogenic variations in the ß-globin gene. Sanger's sequencing of the proband and his family revealed the presence of a novel frame shift variant HBB:c.163delG in a compound heterozygous state with hemoglobin E (HbE) (HBB:c.79G > A) variant. The father and the sibling of the patient were found to be normal for the HBB gene. Mother was found to be heterozygous for HbE (HBB:c.79G > A) variant. In silico analysis by Mutalyzer predicted that c.163delG variant generated a premature stop codon after seven codons, leading to a truncated protein. FoldX protein stability analysis showed a positive ΔΔG value of 45.27 kcal/mol suggesting a decrease in protein stability. HBB:c.79G > A is a known variant coding for HbE variant, which results in the reduced synthesis of ß-globin chain and shows mild thalassemia. Combined effect of HBB:c.163delG and HBB:c.79G > A variants in the proband might have led to the reduced synthesis of ß-globin chains resulting in a thalassemia intermedia type of clinical manifestation.

Novel variants detected in AGT gene among patients with essential hypertension.

INTRODUCTION: AGT is the first gene to be linked to essential hypertension (EHT). It harbors several variants of which only few polymorphisms are found to exhibit positive and negative associations with hypertension. In the present study, the AGT gene was screened to detect already reported and novel variations contributing to the development of hypertension. METHOD: In total, 215 hypertensives and 230 normotensives were screened for variations in all the five exons and a part of promoter of AGT gene using single strand conformation polymorphism analysis followed by sequencing of samples showing mobility shifts on polyacrylamide gels. RESULTS: Five novel variants, namely c.-61G>A in promoter, c.-4+17C>T in intron1, c.24T>C and c.28A>T in Exon2, and c.*90 T>C in 3' untranslated region were detected in the AGT gene. c.-61G>A lies in the promoter region that plays a critical role in its expression. Variation c.-4+17C>T created a new enhancer site. c.24T>C (TCT-TCC) is a silent mutation while c.28A>T (p. M10L) has a possible damaging effect on the AGT protein. c.*90T>C, detected in the 3' untranslated region is thought to play an important role in the translation and stability of the mRNA. CONCLUSION: Studies on the functional role of these novel variants are warranted to understand the mechanism underlying the development of EHT.

Risk conferred by tagged SNPs of AGT gene in causing susceptibility to essential hypertension.

UNLABELLED: Abstract Introduction: AGT gene harbors several variants of which 21 are found to be in high linkage disequilibrium as per Hapmap database. Studies delineating the importance of these tagged SNPs are very limited and lacking from Indian population. In the present study, we evaluated the contribution of four tagged SNPs namely, g.6635G > A, g.6506G > A, g.12840G > A, and g.13828T > C at AGT locus along with the analyses of haplotype and epistatic interactions in causing susceptibility to essential hypertension (EHT). METHODS: About 215 hypertensives and 230 normotensives were genotyped for selected tagged SNPs using PCR-RFLP method. RESULTS: Significant association was obtained for g.6635G > A and g.6506G > A polymorphisms wherein GG homozygotes for both the markers were at risk for developing the condition. g.13828T > C polymorphism specially, female heterozygotes (TC) were found to be at increased risk for EHT. Haplotype GGGC was found to have a significant protective effect (p = 0.0059). Markers g.6506G > A and g.12840G > A resulted in the creation of new enhancer sites thereby affecting splicing process. CONCLUSION: The present report is the first one in the literature showing general- and gender-specific association of g.6506G > A and g.13828T > C polymorphisms, respectively, with EHT. However, further studies for replication of present observations are warranted from other populations and other parts of India.

Total activity of glutathione-S-transferase (GST) and polymorphisms of GSTM1 and GSTT1 genes conferring risk for the development of age related cataracts.

The pathogenesis of cataract is influenced by a number of factors including oxidative stress. Glutathione-S-transferase (GST) catalyses the nucleophilic addition of the thiol of GSH to electrophilic acceptors. It is important for detoxification of xenobiotics in order to protect tissues from oxidative damage. In humans, GSTT1 and GSTM1 deletion genotypes are associated with a variety of pathological conditions including certain ophthalmic diseases. In the present study, it is aimed to determine the risk of genetic polymorphisms of GSTM1 and GSTT1 isoforms of GST for developing of age related cataracts (ARCs). We compared the prevalence of GSTT1 and GSTM1 deletion genotypes, which were determined by multiplex polymerase chain reaction, in 455 patients with ARCs (108 with nuclear (NC), 105 with cortical (CC), 96 with posterior subcapsular, (PSC) and 146 with mixed type (MT)) and 205 age and sex matched controls. The GST activity in erythrocytes (RBC) and cataractous lenses was measured spectrophotometrically using 1-chloro-2,4-dinitrobenzene (CDNB) as substrate. The frequency of GSTM1 positive individuals was significantly higher in MT cataracts followed by NC, CC and PSC types with corresponding decrease in the GSTM1 null genotypes as compared to controls. Considering the GSTT1 locus, GSTT1 null genotypes showed high frequency in patients in general as compared to controls with corresponding reduction in the GSTT1 positive genotype. The activity of GST in RBC was higher in all the types of cataracts as compared to that in controls and in cataractous lenses the mean values were slightly higher in cases of NC cataracts as compared to CC, PSC and MT. The data suggests that GSTM1 positive, GSTT1 null and double null (GSTM1 null and GSTT1 null) genotypes may confer risk for the development of ARC. The increased activity of GST found in the present study could be due to a compensatory mechanism operating in response to increased oxidative stress.

Is the variant c.422+90G → A in intron 4 of indoleamine 2, 3 -dioxygenase (IDO) gene related to age related cataracts?

PURPOSE: To screen for sequence variations in the IDO gene that encodes indoleamine 2, 3- dioxygenase (IDO), the first rate limiting enzyme involved in the tryptophan catabolism which results in the production of UV filters playing a role in the maintenance of lens transparency. METHODS: We conducted a case-control study to screen for sequence changes in the IDO gene and associated demographic risk factors in patients with nuclear (NC-110), cortical (CC-110) and Posterior sub capsular (PSC-111) cataracts in comparison to normal controls (210) from Hyderabad, India. RESULTS: Among the cataract types studied high risk was observed for CC and PSC types in female patients, individuals with low body mass index and smoking habit. Cataract development had early onset more frequently in cases of PSC followed by CC and NC. Screening by single strand conformation polymorphism (SSCP) revealed mobility shifts in 6 of the 331 patient (3 with NC and 3 with PSC) samples which upon sequencing confirmed the presence of G → A transition (c.422+90G → A; rs4613984) in the intron downstream to exon 4 of IDO which was further tested by RFLP analysis using the HhaI restriction enzyme. Of the 6 patients, one with nuclear cataract showed homozygosity and the remaining five showed heterozygosity for the substitution. None of the control samples showed this variation. CONCLUSIONS: It is possible that the substitution c.422+90G → A; rs4613984 in an intron downstream to exon 4 of IDO may be related with cataract formation among the aged.

Polymorphisms in two DNA repair genes (XPD and XRCC1)--association with age related cataracts.

PURPOSE: Age related cataract is the leading cause of blindness in the world today. The association between DNA damage to the lens epithelium and the development of lens opacities has been reported in many studies. Polymorphisms of DNA repair enzymes may affect repair efficiency and thereby lead to the development of age related cataract. METHODS: In this study, we aimed to determine the frequency of polymorphisms in two DNA repair enzyme genes, xeroderma pigmentosum complementation group (XPD) codon 312 and X-ray complementing group1 (XRCC1) codon 399, in a sample of 208 cataract patients (69 with cortical, 69 with nuclear and 70 with posterior sub capsular) and 151 sex and age matched healthy controls. XPD genotype was determined by Amplification Refractory Mutation System (ARMS) while XRCC1 was genotyped using the PCR-RFLP method. RESULTS: There was a significant difference between frequencies for XPD-312 Asn/Asn genotype in cataract patients (21.6%) and healthy controls (13.2%; p=0.03, OR=1.97, 95% CI=1.06-3.63). Considering the types of cataract, XPD-312 Asn/Asn genotype was found to be significantly different in patients with cortical (29%) type in comparison to controls (13.2%; p=0.03, OR=2.39, 95% CI=1.11-5.12). No statistically significant difference was found for the genotypic and allelic distributions of the polymorphism in XRCC1. The MDR interaction analysis revealed weak synergism between the markers XPD-Asp312Asn and XRCC1-Arg399Gln contributing to cataract. It also showed that the AA genotype of XPD-Asp312Asn polymorphism when present in combination with the GA genotype of XRCC1-Arg399Gln had a fivefold and with AA had a fourfold risk for developing cataract. CONCLUSIONS: The present study suggests that a polymorphism in XPD codon 312 may be associated with the development of maturity onset cataract. This is the first report on the association of XPD Asp312Asn polymorphism with maturity onset cataract.

Randomized trial of tacrolimus monotherapy: tacrolimus in combination, tacrolimus alone compared (the TICTAC trial).

BACKGROUND: Prior retrospective studies have suggested that tacrolimus monotherapy is an option associated with excellent outcomes and reduced toxicities. METHOD: We conducted a prospective, randomized, 2-center study of tacrolimus combination therapy vs monotherapy. From April 16, 2004, to September 15, 2005, 58 adult heart transplant patients were studied. All received oral tacrolimus, mycophenolate mofetil, and corticosteroids. Patients were then randomized to a group where mycophenolate was maintained (COMBO) or to a group where it was discontinued (MONO) 14 days post-transplant. Corticosteroids were rapidly withdrawn in both groups between 8 and 12 weeks. RESULT: The primary end point (mean 6-month International Society of Heart and Lung Transplantation biopsy score) was 0.44 +/- 0.04 in the MONO group and 0.60 +/- 0.05 in the COMBO group (p = 0.013, unpaired Student's t-test). The freedom from rejection grade of 2R or higher at 6 and 12 months was 93.3% with MONO and 92.9% with COMBO (p = NS). CONCLUSION: Tacrolimus monotherapy appears to be safe and efficacious in heart transplant recipients and is not associated with excess rejection in the first year post-transplant. Further studies of this approach are warranted.

Is toxoplasmosis prophylaxis necessary in cardiac transplantation? Long-term follow-up at two transplant centers.

Cardiac transplant recipients are often given prophylactic treatments to prevent opportunistic infections such as Pneumocystis carinii. Toxoplasmosis prophylaxis is commonly prescribed for transplant recipients who have not been exposed to this disease but receive a heart from an exposed donor. We reviewed the collective 28-year experience at two urban transplant programs with 596 patients, and found no cases of toxoplasmosis, but all patients received trimethoprim-sulfamethoxazole to prevent Pneumocystis pneumonia. We conclude that specific anti-toxoplasmosis prophylaxis is unnecessary in heart transplant recipients.

Long-term results of tacrolimus monotherapy in cardiac transplant recipients.

BACKGROUND: Conventional immunosuppression for heart transplantation is associated with various adverse effects. Tacrolimus monotherapy (TM) is an alternative strategy that minimizes exposure to additional immunosuppressants. METHODS: We retrospectively reviewed clinical data for all adult transplant recipients between January 1, 1996 and May 1, 2004. Clinical outcomes were analyzed according to immunosuppressive regimen. RESULTS: A total of 167 heart transplants were performed at our center. Eight patients died before receiving calcineurin inhibitors and were excluded from analysis. The mean follow-up for the 159 surviving patients was 1,520 +/- 78 days. Ninety of 124 patients initially treated with tacrolimus and corticosteroids were weaned to TM without the use of an anti-proliferative agent (Group A), resulting in an overall success rate of 75% at an average of 271 +/- 18 days after transplant. The remaining 69 recipients were treated with other tacrolimus- or cyclosporine-based regimens (Group B). Survival was significantly greater in Group A. The prevalence of high-grade rejection within the first year and incidence of cardiac allograft vasculopathy were similar between groups. Ten patients (11%) in Group A required recommencement of combination immunosuppression at an average of 768 +/- 772 days. CONCLUSIONS: TM is achievable in the majority of cardiac transplant recipients. Patients who tolerated reduced immunosuppression enjoyed greater survival than those treated with other regimens, without additional high-grade rejection or vasculopathy. These promising results remain to be confirmed in a prospective trial.