Cytogenetic banding

Detection of specific cytogenetic abnormalities For instance, a small deletion of band Xp21.2 was important in cloning the gene involved in Duchenne muscular dystrophy. 

Satoh, H., Tani, K Yoshida, M. C., Sasaki, M., Miwa, S., and Fujii, H., The human liver-type pyruvate kinase (PKL) gene is on chromosome 1 at band q21. Cytogenet. Cell. Genet. 47, 132-133 (1988). 

Geneticists use maps to describe the location of a particular gene on a chromosome. One type of map uses the cytogenetic location to describe a gene s position. The cytogenetic location is based on a distinctive pattern of bands created when chromosomes are stained with certain chemicals. Another type of map uses the molecular location, a precise description of a gene s position on a chromosome. The molecular location is based on the sequence of DNA building blocks (base pairs) that make up the chromosome. 

Geneticists use a standardized way of describing a gene s cytogenetic location. In most cases, the location describes the position of a particular band on a stained chromosome ... 

Figure 9 Pie chart of the relative percentages of the causes of human birth defects. It has been estimated by various authorities that cytogenetics contributes to no more than 5% of all malformed live births, Mendelian inheritance to no more than 15-20%, maternal infections 3% or 4%, maternal disease 3% or 4%, problems of constraint in utero (amniotic bands) 2%, and all drugs, chemicals, and radiation no more than 1% of the total load of structural birth defects in human beings.

Chromosomes 21 and 22 are quite different not only in their composition, but also in their cytogenetic size. While the DNA amount of the long arms of both chromosomes is comparable (the difference being less than 3%, as defined by Hattori et al., 2000, and Dunham et al., 1999), the cytogenetic size of chromosome 22 is about 40% greater than that of ehromosome 21, as defined at a resolution of 850 bands (Francke, 1994), indieating that DNA is more eompaet in chromosome 21. While it is possible that the size difference between these two chromosomes was overestimated, similar results were obtained when... 

Figure H7 (7.1.7A). liands. isochores and gene eonceniration of human chromosomes 21 and 22. Bands comprise four classes of G bands characterized by diflerent staining intensity (I rom black to pale grey) and two classes of R bands (H3, red H.V, whitel the two chromosomes are represented according to their cytogenetic size. GC profiles are shown through 100 kb windows. Certs/Mb. the blue bar plot concerns chromosomal bands, the red plot 1-Mb segments.

Ambros, P.F. and Sumner, A.Y. (1987). Metaphase bands of human chromosomes, and distinetive properties of telomerie regions. Cytogenet. Cell Genet. 44 223-228. 

Elleder D., Pavlicek A., Paces J., Hejnar J. (2002). Preferential integration of human immunodeficiency virus type 1 into genes, cytogenetic R bands and GC-rich DNA regions insight from the human genome sequence. FEBS Lett. 517 285-286. 

Federico C., Saccone S., Bernardi G. (1998) The gene-richest bands of human chromosomes replicate at the onset of the S-phase. Cytogenet. Cell Genet. 80 83-88... 

Ikemura T. and Wada K. (1991). Evident diversity of codon usage patterns of human genes with respect to chromosome banding patterns and chromosome numbers relation between nucleotide sequence data and cytogenetic data. Nucleic Acid Res. 16 4333-4339. 

Wurster-Hill D.H. and Gray C.W. (1979). The interrelationships of chromosome banding patterns in procyonids, viverrids, and felids. Cytogenet. Cell. Genet. 15 306-331. 

---