Chromosomal abnormalities in couples with repeated fetal loss: An Indian retrospective study.

BACKGROUND: Recurrent pregnancy loss is a common occurrence and a matter of concern for couples planning the pregnancy. Chromosomal abnormalities, mainly balanced rearrangements, are common in couples with repeated miscarriages. PURPOSE: The purpose of this study is to evaluate the contribution of chromosomal anomalies causing repeated spontaneous miscarriages and provide detailed characterization of a few structurally altered chromosomes. MATERIALS AND METHODS: A retrospective cytogenetic study was carried out on 4859 individuals having a history of recurrent miscarriages. The cases were analyzed using G‑banding and fluorescence in situ hybridization wherever necessary. RESULTS: Chromosomal rearrangements were found in 170 individuals (3.5%). Translocations were seen in 72 (42.35%) cases. Of these, reciprocal translocations constituted 42 (24.70%) cases while Robertsonian translocations were detected in 30 (17.64%) cases. 7 (4.11%) cases were mosaic, 8 (4.70%) had small supernumerary marker chromosomes and 1 (0.6%) had an interstitial microdeletion. Nearly, 78 (1.61%) cases with heteromorphic variants were seen of which inversion of Y chromosome (57.70%) and chromosome 9 pericentromeric variants (32.05%) were predominantly involved. CONCLUSIONS: Chromosomal analysis is an important etiological investigation in couples with repeated miscarriages. Characterization of variants/marker chromosome enable calculation of a more precise recurrent risk in a subsequent pregnancy thereby facilitating genetic counseling and deciding further reproductive options.

Plasma chitotriosidase activity in children with lysosomal storage disorders.

Chitotriosidase (ChT) is an enzyme that is selectively activated in tissue macrophage. This property of ChT makes it a potential marker for many disease process and prognostication. Present study has been carried out to know the significance of ChT as a screening marker in lysosomal storage disorders (LSDs) where tissue macrophage activation is commonly observed due to accumulation of substrate in various organs of the body. Study comprises of 20 healthy children in the age range of 10 days to 5 yrs and 56 children in the age range of 2.5 months to 13 yrs with regression of milestones, skeletal dysplasia, neuroregression and hepatosplenomegaly were selected for plasma ChT who had confirmed LSDs as carried out by specific lysosomal enzyme study from the leukocytes or fibroblasts. Plasma ChT was 55.21 ± 20.81 nmol/ml /hr in twenty healthy age matched controls. Plamsa ChT level was 42.88 to 79.78 nmol/ml/hr in thirteen of 56 (23.21%) children with LSDs like Morquio- B, Pompe, Metachromatic leucodystrophy (MLD), Sandhoff and Niemann-Pick disease type C (NPD-C). While in 43 (76.78%) children it was in the range of 213.74 to 23,511.40 nmol/ml/hr. who had LSDs like Morquio-B, Sly syndrome, MLD, GM2 Gangliosidosis, NPD-A/B and Gaucher disease (GD). Marked elevated ChT (4,000 to 23,511 nmol/ml/hr) was observed in all cases of GD (n=7) and NDP-A/B. It can be concluded from the present study that moderately raised activity of ChT can be utilized as a positive predictive test for certain LSD’s. Those with marked elevated ChT have confirmed GD or NPD-A/B making it a strong screening marker for this group of diseases.

Association of HLA-B*1502 allele and carbamazepine-induced Stevens-Johnson syndrome among Indians.

Background: Stevens-Johnson Syndrome (SJS) and toxic epidermal necrolysis are severe cutaneous reactions caused by certain drugs, including antiepileptic carbamazepine. A strong association has been reported between human leucocyte antigen (HLA)-B*1502 and carbamazepine-induced SJS in Han Chinese patients. European studies suggested that HLA-B*1502 is not a universal marker but is ethnicity-specific for Asians. Aim: To study the association between HLA-B*1502 and carbamazepine-induced SJS in Indian patients. Methods: Eight individuals who fulfilled the diagnostic criteria of SJS induced by carbamazepine were identified and HLA-B molecular typing was performed. HLA-B genotyping was carried out by polymerase chain reaction using sequence-specific primers. Results: Out of eight patients studied for genotype, six patients were found to have the HLA-B*1502 allele. Conclusion: This study suggests an association between HLA-B*1502 and carbamazepine-induced SJS in Indian patients.

Niemann-Pick type C disease.

A 4-year-old Afghan girl born to consanguineous parents presented with progressive neurological regression and hepatomegaly noticed after one year of age.The child had hypotonia, repeated unexplained falls and facial dyskinesia. Bone marrow examination revealed presence of storage cells suggestive of Gauchers or Niemann Pick. Confirmatory study by lysosomal enzyme from leucocytes was normal for beta-Glucosidase and sphingomyelinase specific for Gauchers and Niemann Pick type A or B respectively. Further study was carried out on cultured skin fibroblasts in lipid deficient medium using filipin stain which showed presence of dark punctate granules confirming the diagnosis of Neimann-Pick type C, a rare autosomal recessive disorder.

A three way complex translocation (4; 9; 22) in two patients with chronic myelocytic leukemia.

Chronic myeloid leukemia (CML) is genetically characterized by the reciprocal translocation of chromosome 9 and 22, t(9;22)(q34;q11) which results in the fusion of BCR/ABL gene observed on the derivative chromosome 22 called Philadelphia (Ph') chromosome. About 5-8% of Philadelphia positive patients with CML show various complex translocations involving third chromosome in addition to chromosome 9 and 22. In present report we discuss two cases with CML referred at our centre. At the time of initial diagnosis and after 9 months of treatment, one of the patients showed 100% presence of Philadelphia positive in bone marrow culture. During follow-up in an accelerated state, his cytogenetic study revealed a complex translocation (4;9;22)(q25;q34;q11) along with an additional Philadelphia and marker chromosome. The second patient showed a complex (4;9;22)(q25;q34;q11) translocation at the time of diagnosis. He was on hydroxyurea and his follow-up cytogenetic study after the course of chemotherapy showed no changes. Further confirmation of complex translocation was done by FISH study using bcr/abl and whole chromosome 9 probes. Though the additional genes involved in complex variant Ph' rearrangements have not been characterized, both patients are healthy till 3 to 5 years of initial diagnosis. This could be attributed to the benign effect resulted from reciprocal translocation with no loss or gain of the genetic material.

Gene polymorphism and folate metabolism: a maternal risk factor for Down syndrome.

The high birth frequency of Down syndrome (DS), trisomy 21 (T21), has been a subject of interest to the clinicians and researchers due to its complexity in phenotypic expression. In addition to the maternal age, identification of the mechanistic basis for T21 requires an understanding of the cellular-molecular events and other biochemical pathways that could promote maternal meiotic nondisjunction. Recent studies have linked the increased frequency of polymorphism of methylenetetrahydrofolate reductase (MTHFR, C677T) and methionine synthase gene (MTRR, A66G) in mothers with DS child. Based on evidence that abnormal folate and methyl metabolism can lead to DNA hypomethylation and abnormal chromosomal segregation, researchers have observed that mothers with mutation in MTHFR (C677T) and MTRR (A66G) gene have elevated levels of plasma homocysteine. This was found to be associated with a 2.6 to 2.9 fold increased risk of having child with DS compared to mothers without the mutation. Subsequent studies evaluating Italian, Irish, French, and Indian-Gujarati women could not demonstrate an association of MTHFR gene polymorphism in mothers with DS child. However, the Irish study did find an increased risk of DS associated with the MTRR polymorphism and an interactive effect of MTRR and MTHFR polymorphisms with increased risk. Interestingly, an increase in plasma homocysteine was found to be a risk factor for DS in several of the studies. Despite the differences, the published studies suggest a common theme of abnormal folate metabolism associated with increased risk of having a child with DS. These observations suggest that there seems to be a geographic variation in gene polymorphism and it could not be attributable to meiotic nondysjunction in all mothers with DS child but increased homocysteine in all different study group does suggest that there may be a gene-nutritional or gene-gene or gene-nutritional-environmental factors involved in increased frequency of meiotic nondisjunction which needs transnational and multinational study design.

Morquio-B syndrome (MPS-IV B) associated with beta-galactosidase deficiency in two siblings.

In the present article we describe two cases with Morquio-B syndrome characterized by beta-galactosidase deficiency in a Muslim family. They were found to have skeletal dysplasia, short stature and short trunk dwarfism with undetectable level of beta-galactosidase in leucocytes. Probands' sister who had no clinical signs of mucopolysaccharidosis was investigated and found to have normal levels of the enzyme. Mother was found to have a deficient activity of beta-galactosidase and father was not available for the study. Since mother was pregnant, prenatal study from chorionic cells was carried out to investigate beta-galactosidase activity in the chorionic villus. An intermediate level of beta-galactosidase activity was found in the chorionic villus cells suggesting a carrier status. The diversity and rarity of the study makes it worth presenting.