Chromosomal Examination in Medicine

Overview

Aberrations of the normal number and structure of chromosomes can cause mental, growth and developmentaldelay, defects of sexual development, congenital defects, abnormal facial features, deformation of extremities,defective intrauterine development, spontaneous miscarriages, and infertility. Expressive changes of the karyotypeare used to be found in cancer cells. In majority of cases a lot of genes are abundant or deleted and then many organsare affected – therefore disorders are described as „syndromes“. Down and Turner syndromes are the best knownsyndromes caused by numerical aberrations of human chromosomes. In the diagnostics of structural aberrations, theuse of methods of classical cytogenetics becomes limited. Fluorescence in situ hybridisation (FISH) is therefore usedmore frequently. FISH method has several advantages: rapidity, sensitivity, specificity and possibility to apply thismethod also in interphase nuclei. Application of FISH allows us to detect submicroscopic deletions and amplificationsand to explain the aetiology of inborn developmental defects and cancer diseases (including familiar cases). Thenewest FISH modifications perform one step analysis of multiple chromosomal rearrangements and help us toascertain the diagnosis and the prognosis of cancer diseases. The use of special computer software for chromosomaland FISH analysis is the most important part of the current cytogenetic diagnostics.

Key words:
chromosomes, chromosomal rearrangements, cytogenetic diagnosis, fluorescence in situ hybridisation(FISH).