Pseudoautosomal regions

In the human genome, pseudoautosomal regions are the two homologous regions of X and Y chromosomes. The regions are PAR1 and PAR2, and it is believed that these evolved independently. The PAR1 region comprises 2.6Mbp of nucleotides at the tip of the short arms of the X & Y chromosomes, while PAR2 comprises 320kbp at the tips of the long arms.

The genes in these regions are inherited in a similar fashion to autosomes because recombination by crossing over may occur between them (so a female can inherit a portion of her father's Y-chromosomal pseudoautosomal region); they do not follow a sex-linked pattern of inheritance. The regions are essential in allowing the X and Y chromosomes to pair and properly segregate during meiosis.