Genetics is the science of inheritance. It deals with transmission of hereditary factors from the parents to their expression in the children. When a certain disorder is passed on by parents to their children, it is known as a genetic disorder. Whether, the disorder is dominant or recessive and affected person is homozygote or heterozygote would determine the expression of the disease.

Chromosome disorders, biochemical genetic disorders and other genetic disorders of polygenic and Multifactorial origin have varying prevalence. E.g. multiple childbirths. Couple with older age group mothers are known to cause birth of trisomic infants. These conditions are so widely prevalent in our country that the incidence of child born with Down syndrome is not only on the increase but is much more above the figures quoted in western literature.

Chromosome disorders, biochemical genetic disorders and other genetic disorders of polygenic and Multifactorial origin have varying prevalence. E.g. multiple childbirths. Couple with older age group mothers are known to cause birth of trisomic infants. These conditions are so widely prevalent in our country that the incidence of child born with Down syndrome is not only on the increase but is much more above the figures quoted in western literature.

Human chromosomes are composed of DNA (genes), which provide the basic information to develop, maintain and reproduce an entire human being. All of this information is contained in 46 chromosomes. The chromosome complement includes 22 pairs of autosomes and either XX (female) or XY (male) sex chromosomes. In a body every nucleated cell contains this complement, therefore the analysis can be preformed on any dividing cell type (lymphocytes fibroblasts, bone-marrow cells etc.)  As mentioned above, these cells provide considerable information 

1. sex chromosome abnormality ( Klinefelter’s and Turner’s syndromes etc.)
   Autosome related abnormality with changes in modal number, translocations or rearrangements (Down’s syndrome, infertility, or increased spontaneous abortions). Chromosome breakage following exposure to radiation or chemicals with increased gaps, breaks and the presence of fragments.

2. A second population of cells for cytogenetic study is the leukemic cells. Leukemic blast cells are found primarily in bone-marrow and under certain conditions in the peripheral blood. After culturing these cells, the chromosome pattern is studied for modal number, the presence of specific translocations ( i.e. classical  Ph’ chromosome t(9;22), and unusual structural rearrangements. The presence of marker chromosome is often valuable in identification of the malignant population during therapy.

3. The third population of cells to study are those derived from fetus in Utero. During gestation, the fetus sheds cells into the amniotic fluid. At around 16 weeks, the clinician can locate the fetus with sonography and remove 20-30 cc. of A.F for analysis. These cells are cultured which takes around 15-25 days and ultimately chromosomes are studied for any abnormality. 

The laboratory uses several methods for determination of fine structure and identification of individual chromosomes. These include Giemsa-trypsin banding, quinacrine fluorescence and centromere banding techniques. On each specimen 20 well spread cells are analysed and photographed. In case of mosaicism, more cells are examined. We are proud to say that most recent introduced updating auto karyotyping system by us is playing excellent  and exclusive role in analyzing the chromosomes leading much more sensitive & specific results.

Novel laboratory techniques are often the driving force behind new ideas in science. Certainly the use of cytogenetic studies for clinical testing literally exploded in the ‘60s and ‘70s because of new discoveries. In the 1980s the techniques of molecular biology were applied to cytogenetic preparations. We call this “hybrid” technology molecular cytogenetics, and it is transforming the way we study chromosomal changes in humans. It has improved the detection of indeed in some cases defined, microdeletion syndromes. The supernumerary markers can be identified and we now have a real potential of predicting phenotype for marker carriers, benign or adverse. With molecular cytogenetic techniques, we can now detect some chromosomal abnormalities in nondividing cells with interphase nuclei. Standard cytogenetics requires actively dividing cells with metaphase nuclei. Some constitutional chromosomal abnormalities and phenomena such as mosaicism and chimerism can be addressed without growing cells in culture or in cell types that do not adapt well to tissue culture. Potentially, chromosomal aneuploidy studies (i.e. studies looking for abnormalities in chromosome number) can be done more quickly. Preserved, rather than fresh, tissue can be investigated for retrospective studies. We can ask questions of chromosome organization, its relationship to gene expression and tissue specificity in ways that were not possible a few years ago.

In recent years the possibilities for visualizing several chromosomal targets simultaneously has meant that Fluorescence In situ Hybridization (FISH) analysis has an increasing role to play in the study of patient samples. The clinical cytogenetics service laboratory no longer focuses on the morphological analysis of chromosomal aberrations alone, but now has provided comprehensive molecular cytogenetic analysis of diverse gene sequences consistently involved in certain classes of cancer and a variety of human genetic diseases.