2012-05-19
Blood kariotyping
All human genes are packed appropriately and form structures called chromosomes. Human has 46 chromosomes (22 autosomes and a pair of sex chromosomes –XX or XY). The whole of chromosomes in the cell is called karyotype.
Every human somatic (asexual) cell contains complete complement of chromosomes (46 chromosomes - 2n), and therefore cell karyotype often is called human karyotype. Female’s karyotype is 46, XX, and male’s karyotype is 46, XY.
Karyotyping is cytogenetic technique enabling visually evaluate person’s chromosome entity: their number, structure and sex chromosomes. Only gross chromosomal changes are evaluated during this test.
Cells (blood or bone marrow cells) for karyotype analysis are grown in special medium. After that cell growth is stopped at metaphase (spiral chromosomes are clearly visible in this cell division phase), cells are smeared on microscope slide, fixed, stained and analyzed by microscope using special computer software.
Blood karyotyping
Analysis is used for postnatal diagnostic (after child’s birth). Human karyotype analysis is recommended in case of:
•family infertility, where analysis is necessary for both partners;
•frequent (two or more) miscarriages, analysis is necessary for both partners;
•sexual disorders:
multiple malformations;
mental retardation;
family history of chromosomal diseases.
Venous blood is used for analysis; blood samples are collected on Mondays and Tuesdays (blood is collected into test-tubes with heparin anticoagulant). Analysis results are presented after 7-10 days.