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.

Fetal cells in maternal blood for prenatal diagnosis.

Advances in molecular genetics have led to prenatal DNA diagnosis, using either invasive or noninvasive approach. Fetal cells are one of the sources for prenatal diagnosis. Standard prenatal genetic diagnosis currently involves chorion villus sampling (CVS) or amniocentesis, which are invasive techniques. Noninvasive methods such as maternal serum biochemical screening (triple markers) in combination with ultrasonography can now detect a large percentage of chromosomal and congenital anomalies. However their lack of optimal specificity and sensitivity compels the use of invasive techniques, which pose a small but significant risk of pregnancy loss. The presence of fetal cells in maternal circulation as early as 6 weeks of gestation has opened new avenues of noninvasive approach to prenatal diagnosis in identifying successfully both Chromosome and molecular genetic abnormalities. Several attempts have been made to detect and retrieve fetal nucleated cells including nucleated erythrocytes (NRBCs), leucocytes and trophoblasts in maternal blood. A number of clinical and laboratory studies are continuing throughout the world to determine the feasibility of isolation of fetal cells from maternal blood and its subsequent use in genetic diagnosis by FISH and PCR technology. This article thus reviews the latest literature on fetal cells from maternal blood with an intention of pursuing research with this novel noninvasive approach, which is the need of today in India.