Yes, it is possible for a male to have no Y chromosome. While the Y chromosome typically carries the SRY gene responsible for male sex development, rare instances exist where individuals develop as males despite lacking a Y chromosome.
This phenomenon, known as XX male syndrome, occurs due to a translocation of the SRY gene from the Y chromosome to another chromosome, usually an X chromosome. In such cases, even though the individual has two X chromosomes, the presence of the SRY gene on a different chromosome triggers male development. These individuals typically develop male external genitalia but may have some degree of infertility.
Examples:
- About 1 in 20,000 men lacks a Y chromosome and instead possesses two X chromosomes.
- Individuals with XX male syndrome have male characteristics despite the absence of a Y chromosome.
This highlights that while the Y chromosome is traditionally associated with maleness, the presence or absence of a Y chromosome is not the sole determining factor in sex development. Other factors like genetic mutations, hormonal influences, and even environmental factors can play significant roles.
