KARYOTYPING

it is the process of paring the all chromosomes of the organism.

1. KARYOTYPING By SATHISHKUMAR G ([email protected])

2. INTRODUCTION KARYOTYPE KARYOTYPING CHROMOSOME STRUCTURE TYPES 1) ASYMMETRIC KARYOTYPE 2) SYMMETRIC KARYOTYPE OBSERVATIONS HUMAN KARYOTYPE CHROMOSOMAL ABNORMALITIES OBJECTIVES

3. INTRODUCTION: KARYOTYPING is the process of pairing and ordering all the chromosomes of the organism. Thus providing a genome-wide snapshot of an individual’s chromosome. Clinical CYTOGENETICISTS analyze human KARYOTYPES to detect gross genetic changes-anomalies involving several MEGABASES or more of DNA. KARYOTYPES can reveal changes in chromosome number such as down syndrome ,structural changes such as chromosomal deletions , duplications, translocations or INVERTIONS. KARYOTYPING are becoming a source of diagnostic information for specific birth DEFECTS,GENETIC disorders and cancers.

4. KARYOTYPE: The complete chromosomal set of nucleus of the cell. The diagrammatic representation of a KARYOTYPE with all of pairs of chromosomes arranged in the order of size called an Ideogram. The preparation and study of KARYOTYPES is a part of CYTOGENETICS.

5. KARYOTYPING: A Karyotype is a number and APPERANCE of chromosomes in the nucleus of a Eukaryotic cell. The term is also used for the complete set of chromosomes in the species are in the individual organisms and for a test that defects this complement or measures the number.

6. CHROMOSOME STRUCTURE: Chromosomes are composed of chromatin ,a combination of nuclear DNA and protein. For KARYOTYPING cells are captured in metaphase. A metaphase stage in mitosis at which the chromosomes are aligned along the cell equator.

7. TYPES OF KARYOTYPE: Karyotype is classified into two types 1.Asmmetric Karyotype 2.Symmetric Karyotype

8. ASYMMETRIC KARYOTYPE: The karyotype which show large difference between smaller and large chromosomes in a set. Have more acrocentric chromosomes. Have relatively advanced features. SYMMETRIC KARYOTYPE: The karyotype which show lesser difference between smaller and large chromosomes in a set. Have more metacentric chromosomes. Have no relatively advanced features.

9. OBSERVATIONS ON KARYOTYPES: The study of karyotypes is made possible by staining. Usually a suitable dye ,such as GIEMSA, is applied after cells have arrested during cell division by a solution of colchicine usually in metaphase or when most condensed. In order for GIEMSA to adhere correctly , all the chromosomal proteins must be digested and removed.

10. HUMAN KARYOTYPE: The normal human karyotype contains 22 pairs of Autosomal chromosomes and one pair of sex chromosomes. The KARYOTYPES for female contains two X chromosomes and are denoted as XX. The KARYOTYPES for male contains both X and Y chromosomes and are denoted as XY. Any variation from the standard KARYOTYPE may lead to developmental abnormalities.

11. NORMAL KARYOTYPE

12. CHROMOSOMAL ABNORMALITIES: Chromosomal abnormalities can be numerical, as in the presence of extra or missing chromosomes or structural ,as in derivative chromosomes such as translocations, duplication. Numerical abnormalities are known as Aneuploidy results in formation of TRISOMERS , in which three copies of the chromosomes are present instead of two.

13. Chromosomal abnormalities that leads to disease in human includes TUMER SYNDROME results from a single X chromosomes(45 X ). KLINEFELTER SYNDROME ,the most common male chromosomal disease caused by an extra X chromosomes. EDWARDS SYNDROME is caused by TRISOMY ( three copies ) of chromosome 18. DOWN SYNDROME is a common chromosomal disease caused by TRISOMY of chromosome 21.

14. OBJECTIVES OF KARYOTYPING: To understand the structure of chromosomes. To understand various banding techniques and their applications. To identify the sex of individuals through AMINOCENTESIS.

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