TABLE 2

Average GC content at third codon position (GC3) in genes located in autosomes, pseudoautosomal regions (PAR), or non-PAR regions of X and Y chromosomes

ChromosomeAverage GC3SEGene no.
Y50.763.5823
X56.300.64438
Autosome62.140.215729
PAR76.194.2811
  • Complete human protein coding sequences were selected from HOVERGEN (Duret et al. 1994) release 40 (May 2000). Pseudogenes and sequences <100 bp were excluded. We also dismissed immunoglobulin and T-cell receptor genes. The average GC3 is higher in PAR than in autosomes (Student's t-test = 2.96, P = 0.003) and higher in autosomes than in X (Student's t-test = 7.57, P < 0.0001). The average GC3 is slightly higher in X than in Y, but the test is only marginally significant (Student's t-test = 1.89, P = 0.0593).