Y chromosome reveals hidden sequence
Extra genes may determine men's height and health.
The Y chromosome is often viewed as relatively empty of genetic information, but a recent analysis suggests it could have a more important function than many suspected.
The chromosome plays a crucial role in determining male sex in humans. The DNA that makes up the chromosome is highly repetitive, making it very difficult to sequence. But in June 2003, researchers in the United States announced that they had done so, and had found 78 genes, including several involved in sperm production.
Now, however, scientists at the University of Heidelberg in Germany have given it another go and found a region of the chromosome that originally went undetected.
When they initially compared the physical map of the chromosome with the cloned sequence, the sequence didn't seem to be long enough, explains team member Gudrun Rappold. "So we took the effort to sort out what was going on."
The new section spans just over half a million base pairs of DNA. "I was very surprised," says Rappold. "That's about 2% of the chromosome that was not detected before." Her team reports the result in Genome Research1.
The region contains eight sequences that appear to be new genes. "We have to check if they are functional," cautions Rappold. But after comparing these sequences with others, she speculates that they may be involved in determining men's height, and may also provide clues about cancers of male sex organs.
- Kirsch, S. et al. Genome Res. 15, 195–204 (2005).