Portal de Periódicos da CAPES

Human Chromosomal Heteromorphisms: Nature and Clinical Significance

1980; Elsevier BV; Linguagem: Inglês

10.1016/s0074-7696(08)61903-8

2163-5854

Ram S. Verma, Harvey Dosik,

Plant Genetic and Mutation Studies

The heteromorphic chromosomes of the human genome can be classified by size, position, staining intensity, or any combination of these types using various banding techniques, such as QFQ (Q-bands by fluorescence using quinacrine), CBG (C-bands by barium hydroxide using Giemsa), and RFA (R-bands by fluorescence using acridine organe). The classification of different types of heteromorphisms is based on estimation rather than actual measurements. Moreover, variation is continuous rather than discrete. However, several attempts are made to classify them on the basis of arbitrary scales and different codes (levels) are assigned. Chromosomal heteromorphisms found in human chromosomes provide a useful tool for several studies because they are inherited in a Mendelian fashion, are stable, and are presumed to have a low mutation rate. By using heteromorphic markers of chromosome 21, the origin of the extra chromosome in Down syndrome can be determined. Applications of heteromorphisms as markers is in elucidating the chromosomal mechanisms involved in the production of mosaics, in studying chimeras, and in following the fate of transfused or transplanted cells.