Evaluation of Paper-Based Point of Care Screening Test for Sickle Cell Disease.

The aim of the study is to evaluate the stability and longevity of the paper-based screening test for the sickle cell disease in relation to different temperatures and storage time. Blood stain patterns were interpreted after spotting the blood-buffer mixture (phosphate buffer, saponin and sodium metabisulfite) on chromatographic paper (Whatman no. 3). The stability of the buffer was tested after keeping the buffer at different temperature for 24 h. Longevity of the buffer was tested post storage for various time intervals. Test indicated reproducibility with the buffer stored at 4°C. The 15% metabisulfite buffer was found to be stable up to 180 days at 4°C and showed accurate identification of all genotypes. The tests revealed 100% sensitivity and 100% specificity in identification of HbS. However, the sensitivity of differentiation between sickle cell trait (AS) with disease (SS) was found to be 97.7% with 100% specificity. The paper-based screening test may be used as a method of choice for the screening of sickle cell anemia in community-based screening programs. The low-cost, rapid, and accurate point of care testing tools offer an avenue for effective screening in developing nations.

Krüppel-like factor 1 (KLF1) gene single nucleotide polymorphisms in sickle cell disease and its association with disease-related morbidities.

Sickle cell disease has varied clinical symptoms, and patients having high fetal hemoglobin (HbF) have milder symptoms. Various genetic factors are known to modulate the HbF levels. Krüppel-like factor 1 (KLF1) is a transcription factor that regulates the beta-like globin gene expression. Any variation in KLF1 gene may alter the sickle cell disease phenotype. Xmn-I polymorphism is also known to regulate the gamma globin gene expression. Present studies were carried out to investigate the effect of KLF1 gene mutations and Xmn-I polymorphism on the sickle cell disease severity and to ascertain the genotype-phenotype correlation. One hundred and eighteen sickle cell disease patients having a median follow-up of 5 years (3-10 years) were recruited. Clinical details were recorded from their retrospective medical records. Xmn-I polymorphism were analyzed using PCR-RFLP method. Variations in KLF1 gene were identified using Sanger sequencing. Out of 118 patients, 24 had acute chest syndrome and 21 patients had more than 2 pain episodes per year. There were no significant differences in sickle cell disease-related morbidities in male and females barring leg ulcers. A total of 6 polymorphism were observed in KLF1 gene, out of which 3 are novel (c.-304G > C, c.*141A > G and c.*178A > G). No statistically significant association of any of SNPs identified in KLF1 gene or Xmn-I polymorphism was seen with HbF levels as well as the sickle cell disease-related morbidities. No association exists between fetal hemoglobin or sickle cell disease-related morbidities and Xmn-I polymorphism or with SNPs identified in KLF1 gene in the studied cohort.

Endothelial nitric oxide synthase gene polymorphism is associated with sickle cell disease patients in India.

Patients with sickle cell disease (SCD) produce significantly low levels of plasma nitric oxide (NO) during acute vaso-occlusive crisis. In transgenic sickle cell mice, NO synthesized by endothelial nitric oxide synthase (eNOS) enzyme of vascular endothelial cells has been found to protect the mice from vaso-occlusive events. Therefore, the present study aims to explore possible association of eNOS gene polymorphism as a potential genetic modifier in SCD patients. A case control study involving 150 SCD patients and age- and ethnicity-matched 150 healthy controls were genotyped by PCR-restriction fragment length polymorphism techniques for three important eNOS gene polymorphisms-eNOS 4a/b, eNOS 894G>T and eNOS -786T>C. It was observed that SCD patients had significantly higher frequencies of mutant alleles besides heterozygous and homozygous mutant genotypes of these three eNOS gene polymorphisms and low levels of plasma nitrite (NO2) as compared with control groups. The SCD severe group had significantly lower levels of plasma NO2 and higher frequencies of mutant alleles of these three SNPs of eNOS gene in contrast to the SCD mild group of patients. Haplotype analysis revealed that frequencies of one mutant haplotype '4a-T-C' (alleles in order of eNOS 4a/b, eNOS 894G>T and eNOS -786T>C) were significantly high in the severe SCD patients (P<0.0001), whereas the frequency of a wild haplotype '4b-G-T' was found to be significantly high (P<0.0001) in the SCD mild patients, which indicates that eNOS gene polymorphisms are associated with SCD patients in India and may act as a genetic modifier of the phenotypic variation of SCD patients.

Evaluation of Microchip-Based Point-Of-Care Device "Gazelle" for Diagnosis of Sickle Cell Disease in India.

Sickle cell disease is a major public health problem in India. Lack of rapid and reliable diagnostic methods result in many avoidable deaths in affected population. Current diagnostic tools are laboratory based, expensive and need trained manpower. Here, we evaluated the performance of a microchip-based cellulose acetate electrophoresis test, "Gazelle" in the tribal-dominated Indian states of Chhattisgarh and Madhya Pradesh. A total of 1,050 patients were screened by sickle cell solubility, hemoglobin (cellulose acetate) electrophoresis, high-performance liquid chromatography (HPLC) and Gazelle. Of the total 1,027 test results obtained, 960 tests were "Valid" (93.5%) and included in the analysis. Gazelle identified all patients with disease (HbSS and Thalassemia Major) with 100% accuracy. Gazelle demonstrated 100% sensitivity when comparing sickle cell disease (SCD) vs. sickle cell trait and SCD vs. normal. Specificity was 98.9% and 99.5% when comparing SCD vs. trait and trait vs. normal, respectively. Specificity was 99.8% when comparing SCD vs. normal and sensitivity was 99.3% when comparing trait vs. normal. Overall, Gazelle yielded a high accuracy (99.0%) compared to reference standard tests (hemoglobin electrophoresis and HPLC). Gazelle is a low-cost, rapid diagnostic test with high accuracy for detecting SCD both quantitatively and qualitatively. Gazelle can be a potential screening tool for the rapid diagnosis in resource limited settings and developing countries with high burden of hemoglobin disorders.