Clinical examination and hematological data in asymptomatic & apparently healthy school children in a boarding school in a tribal area.

In a boarding school of Maharashtra State of India 314 students (Bhil & Pawar) were examined clinically and blood was examined. Anemia was present in 16.2% male & 38.3% female. B (Beta). Thalasemia trait was present in 1.6% male & 2.4% female. Sickle cell trait was present in 21.3% male and 14.4% female and sickle cell disease in 0.6% student. G6PD deficiency was seen in 5.1% male & 4.8% female students.

Splenomegaly in school children in a remote tribal area of Dhole district, Maharashtra.

Sickle-cell gene is known to protect against P. falciparum infection and provides a selective survival advantage in those areas where P. falciparum infection is endemic. This protection is not absolute and many other factors, inherited and acquired also contribute to the immunity against P. falciparum infection. We investigated incidence of splenomegaly and typical history of malaria in the past two years in apparently healthy school children in a tribal area in Dhole district of Maharashtra to see whether the incidence of malaria (splenomegaly and typical history) was different in children having sickle-cell trait to that of those who did not have this trait. A total of 480 school children were clinically examined for splenomegaly and history of typical malaria fever and/or blood slide positivity for malaria in the past two years. About 9.55 per cent of normal population had either splenomegaly or convincing history of malarial infection in the past two years which is not statistically different from the sickle-cell trait patients having evidence of past malaria (8.79 per cent; p > 0.05).

Detection of the beta s gene: an evaluation of the solubility test against automated chromatography and haemoglobin electrophoresis.

The solubility test is evaluated against automated high-performance liquid chromatography (HPLC) and haemoglobin (Hb) electrophoresis for its efficacy in screening for the beta s gene in population groups in remote areas. Blood samples taken from 3246 individuals from the tribal populations of the Dhule and Gadchiroli districts of Maharashtra state were analysed by all three methods. The solubility test detected 871 out of 932 individuals positive for the beta s gene by HPLC and Hb electrophoresis, and showed an overall sensitivity of 93.8% and specificity of 100%, with a positive predictive value of 100% and negative predictive value of 97.4%. Both HPLC and Hb electrophoresis are relatively expensive and not available in most laboratories in remote tribal areas, where the frequency of the beta s gene is very high. We conclude that the solubility test could be used for preliminary screening to determine the prevalence of the beta s gene in different population groups, particularly in remote areas where other facilities are not available. Individuals who test positive for the beta s gene by the solubility test require further investigation by either HPLC or Hb electrophoresis.

The influence of alpha-thalassaemia on the haematological & clinical expression of sickle cell disease in western India.

We evaluated the clinical and haematological features of 29 sickle cell anaemia patients with associated alpha-thalassaemia and 22 sickle cell homozygotes with a normal alpha-globin genotype from western India. The presence of alpha-thalassaemia resulted in significantly higher haemoglobin (Hb), haematocrit (HCT), red blood cells counts (RBC) and haemoglobin A2 (HbA2) levels but lower mean cell haemoglobin (MCH) and mean cell volume (MCV). The clinical presentation in these patients was also milder with fewer episodes of painful crisis, chest syndromes, infections, requirement of hospitalization and blood transfusions. However, splenomegaly was more common as compared to the patients with a normal alpha-globin genotype. It is evident from the present study that alpha-thalassaemia could be an important genetic factor modulating the clinical expression and haematological severity of sickle cell anaemia in this region.

Trimodal distribution of HbS levels in sickle heterozygotes--an useful predictor of the alpha-genotype for population screening.

The trimodal distribution of HbS levels in sickle heterozygotes has been used as an indirect approach to determine the prevalence of alpha-thalassaemia in different population groups. We used this approach to predict the alpha-genotypes of 124 sickle cell heterozygotes where the HbS concentration varied from 20 to 46 per cent with antimodes at 28.0 and 33.0. The alpha-genotypes in these individuals were also determined by Southern blot hybridization. We predicted homozygous (-alpha/-alpha) or heterozygous (-alpha/alpha alpha) alpha-thalassaemia-2 in 78 subjects by the trimodal distribution of HbS. However, actual genotyping showed that 75 patients had alpha-thalassaemia. Forty six of the 47 subjects with a normal alpha-globin genotype (alpha alpha/alpha alpha) could be predicted indirectly. The overall sensitivity was 100 per cent and specificity was 94.2 per cent with a positive predictive value of 96.2 per cent and negative predictive value of 100 per cent. As alpha-genotyping is very expensive and not feasible in most laboratories in India, we conclude that the trimodal distribution of HbS levels is a suitable method for screening for alpha-thalassaemia in population studies.