Differentiation of Nijmegen breakage syndrome from Fanconi anemia

Nijmegen breakage syndrome (NBS) is a rare auto-somal recessive condition with chromosomal instability. Clinical and biological overlap between Fanconi anemia and ataxia telangiectasia has been reported. We report two cases of NBS born to consanguineous parents. Case one had NBS and Falconi anemia clinical features but relatively little chromosome breakage. The second case had mild NBS features, while cytogenetic evaluation with mitomycin C induction showed chromosome damage. Chromosomal analysis of bone marrow cells revealed tetraploidy, which indicates progression towards leukemia. On the basis of clinical and cytogenetic evaluation, these two cases were confirmed as NBS. However, detailed molecular studies are essential for accurate diagnosis and management of this disease.

Cytogenetic studies of 1001 Down syndrome cases from Andhra Pradesh, India.

Cytogenetic data obtained from investigating 1001 patients of Down syndrome (DS) and their parents over a period of 20 years (January 1979-January 1999) are presented. The frequency of pure trisomy, mosaicism and translocation was 87.92, 7.69 and 4.39 per cent respectively. The origin of the extra chromosome 21 due to meiotic non-disjunction was 79.24 per cent maternal and 20.76 per cent paternal. A high frequency of acrocentric chromosome associations was also observed in mothers of children of Down syndrome, this might have predisposed to an enhanced risk for non-disjunction. Birth order of DS showed a higher number of first and second borns. Reproductive performances of the parents indicated a high rate of abortions, compared to controls. Cytogenetic investigations carried out over these years greatly helped in the management of these children and for counseling the affected families.

Serum and erythrocyte magnesium levels in hypertensives and their first degree relatives.

Essential hypertension is an arbitrarily defined disorder to which both genetic and environmental factors contribute. Magnesium and its interactions with other cations may play an important role in the pathogenesis of essential hypertension. Various studies have been carried out on the levels of serum and erythrocyte magnesium in hypertensives and the results are controversial and there is no systematic study in Indian population. In the present study serum and erythrocyte magnesium levels in 86 hypertensives and their 77 first degree relatives as well as in sex and age matched controls were studied. Serum and erythrocyte magnesium levels showed a significant decrease both in the hypertensives and their first degree relatives (p < 0.01). The significantly decreased levels of magnesium in the first degree relatives suggest genetic basis of essential hypertension and may be used as marker to identify those at risk.

Maternal reproductive history and the occurrence of Down's syndrome.

Reproductive history of mothers of 115 Down's syndrome children was studied and compared with 200 control mothers who gave birth to normal children. The frequency of spontaneous abortions in mothers of Down's syndrome babies was found to be elevated significantly (p < 0.05). The data suggest that the maternal health and reproductive potential have a prominent aetiological significance in the occurrence of Down's syndrome.

Detection of haemoglobin variants for the diagnosis of beta thalassaemia & other haemoglobinopathies using anion exchange high performance liquid chromatography.

We describe the precise identification, separation and quantitation of several haemoglobin (Hb) variants such as Hbs A2, A, F, S, E, J, H, D-Punjab and Q-India in untransfused patients with beta thalassaemia and other haemoglobinopathies prevalent in the Indian population using whole blood (5 microliters), red cell lysates (2 microliters) or dried blood specimens on filter paper, using a conventional anion exchange high performance liquid chromatography (AX-HPLC) system. Samples were simultaneously studied for the presence of haemoglobin variants by alkaline electrophoresis. The problems in analysing rare variants and separating the closely migrating variants, encountered in the conventional methods could be resolved using the HPLC technique.