Nonrandom gene distribution on human chromosomes

Abstract

Human chromosomes are heterogeneous in structure and function. This is the reason for specific banding patterns produced by various chromosome staining techniques. The human genome is a mosaic of isochors and can be partitioned into five families, L1, L2, H1, H2 and H3, characterized by increasing GC level and gene concentrations. In this study we investigated the chromosome distribution of 22845 genes mapped at whole chromosomes reported in the Human Genome Data Base as of January 2007. Pearson correlation coefficient analysis showed that there is significant correlation between the number of mapped genes and percent of G-dark bands (r=-0.608, p=0.002). Also the correlation between the ratio (observed versus expected genes) and percent of G-dark bands was significant (r=-0.506, p=0.012). There was a significant difference between observed number of mapped genes and expected number of mapped genes on human chromosomes (?2=4842.7, df=23, p<0.00001). Taken together, these findings indicating the gene density in G-light bands is higher than that of the G-dark bands.