Ways of differential coloring: Q, G, R, C.

а) Q – segments (quinacrine) are the sites of chromosomes fluorescing after coloring quinacrine – yperite. Q – segments correspond to sites rich A – Т pairs of DNA. By means of Q-method possible to identify Y- chromosome of the human as pair luminous points. For viewing it is necessary to use a luminescent microscope.

b) G – segments (Giemsa). First chromosomes are process protease (or incubate in a salt solution). This processing breaks structure of chromosomes which is restored at painting in part. That gives individual striation (it is supposed, that the painted segments – heterochromatin, the unpainted segments - euchromatin).

C) R – segments (reverse) are painted after thermal denaturizing. R – segments correspond to sites rich G – C pairs of DNA which are steadier to thermal denaturizing.

d) C – segments (constitute heterochromatin). It is a painting of perycentromere areas of chromosomes.

Achievements of molecular cytogenetics have allowed introducing in clinical cytogenetics to new technologies such as DNK-diagnostics, hybridization of nucleonic acids on a preparation, computer systems for analysis of chromosomes. DNK diagnostics is based use of technology recombination molecules DNK for revealing molecular-genetic defects of chromosomes. Fluorescent hybridization on preparation,FISH – diagnostics( Fluorescent In Situ Hybrization) includes application fluorescing DNK-tests for revealing genetic defects at a chromosomal level. Identification of a chromosomal pathology is based on use various DNA-probes allowing to mark individual chromosomes or their separate sites.

In 1960 the special commission had been authorized general system of a designation of chromosomes of the human (Denver, the USA). All chromosomes are numbered from 1 up to 22 according to their length, and also other features of their structure. Sexual chromosomes have no numbers and are designatedX andY.

Group A (1 – 3 pairs). 1 and 3 pairs are large metacentric chromosomes, 2 pair is submetacentric chromosomes. The first chromosome contains secondary strangulation in subcentromere area of one of shoulders.

Group B (4-5 pairs). Large submetacentric chromosomes.

Group C (6 – 12). Middle submetacentric chromosomes. The X – chromosome is similar to the longest chromosomes of this group with 6-th and 7-th. 6, 7, 8 and 11 pairs of chromosomes from this group are more metacentrics. 9,10,12 pairs of chromosomes are more submetacentric. The 6-n chromosome has secondary strangulation on a long shoulder.

Group D (13 – 15 pairs). Middle acrocentric chromosomes. All three pairs of chromosomes are potential satellite. The long shoulder of one of these chromosomes has secondary strangulation.

Group E (16 – 18 pairs). Short submetacentric chromosomes. The chromosome 16 – 17 contains on a long shoulder secondary strangulation.

Group F (19 – 20 pairs). Short metacentric chromosomes.

Group G (21 – 22 pairs). Very short acrocentric chromosomes. Two chromosomes on a short shoulder have satellites.

The X-chromosome belongs to group C.

The chromosome belongs to group G. It is a small acrocentric chromosome, has no satellites. It differs from chromosomes 21 and 22 to length a shoulder. In the middle of a long shoulder is present secondary strangulation.

Cardiograms or ideogram is an arrangement of chromosomes on groups in decreasing order the sizes.