ABSTRACT
Techniques for analysis of chromosome number and structure in humans were developed in the same decade as the elucidation of the structure of DNA. Almost immediately upon the development of routine methods for laboratory cytogenetic analysis, a set of syndromes was identified as being due to chromosomal abnormalities. As the technology has gradually im proved, there has been a corresponding refinement in the ability to detect increasingly subtle changes in chromosome structure that are clinically im portant. Most recently, cytogenetic methodology has merged with DNA tech nology through fluorescent in situ hybridization (FISH) to permit detection of chromosomal deletions too small to be visualized through the conven tional light microscope.
