The Y- Chromosome is found only in males and is always found paired with an X-chromosome. The Y-Chromosome is the chromosome which determines sex and is always found with an X chromosome. In issues relating to paternity, paternal lineage and relationship testing it is the sex determining region Y (SRY gene) that is analysed. You may find more information about this on DNA Relationship Testing. The Y chromosome constitutes around 2% of the total DNA found in cells. The Y-chromosome contains information about sperm cell development, and thus missing parts of the chromosome means that fertility is affected.
The Y chromosome along with the X is the sex-determining chromosome that defines the sexual development of a fetus. The difference between a male and a female is the Y chromosome, whereby females are XX and males are XY. As the second X in women is responsible for having children and the development of the female genetalia, the Y chromosome in males is also responsible for procreation. It encourages testicular development and male fertility.
The Y chromosome is passed on from father to son and is accountable for approximately 2% of the total DNA, spanning across around 58 million base pairs of chromosomes. Males usually have 23 pairs of XY chromosomes. There are certain conditions which directly affect Y chromosome expression and these include:
- XYY syndrome males who inherit an extra Y chromosome
- Jacobs syndrome
- Klinefelter syndrome
- Intersex conditions
A male’s sperm cells are heterogametic. ‘Gametic’ comes from the word gamete which is another word for sperm cells. ‘Hetero’, meaning different, in this case refers to the X and Y chromosomes that are produced by males. Males produce two types sperm (gametes), a Y chromosome and an X chromosome.
When testing male relatives within a family, a Y-STR test may be performed in order to determine whether there is a biological relation. There are several reasons for wanting to test the Y chromosome including: immigration, adoption, sibling matches among others.