Source: TH
Context: Recent studies from Italy and the USA report rare cases where biological females carried the SRY gene, challenging conventional understanding of sex determination.
About Baby Sex Determination:
- What is Sex Determination?
- Sex determination is the biological process that decides whether a baby develops as a male or female, influenced by genetic and hormonal factors.
- Role of Chromosomes in Sex Determination:
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- Humans have 23 pairs of chromosomes, including one pair of sex chromosomes: XX (female) or XY (male).
- Egg cells always carry an X chromosome, while sperm cells carry either X or Y.
- If a sperm with an X chromosome fertilizes an egg, the baby is female (XX); if a Y-carrying sperm fertilizes the egg, the baby is male (XY).
- What is the SRY Gene?
- The SRY (Sex-determining Region Y) gene is found on the Y chromosome and acts as the master switch for male development.
- Function: It activates a cascade of genes that trigger the formation of testes in the embryo, which then produce testosterone, promoting male characteristics.
- SRY Absence: If the SRY gene is missing or non-functional, the embryo develops female reproductive structures by default.
- How SRY Gene Influences Sex Determination?
- Normal Process: If the SRY gene is present and functional, the embryo develops into a male; if absent, it follows the female pathway.
- Rare Exceptions: Sometimes, the SRY gene translocates (moves) from the Y chromosome to the X chromosome due to mutation. This can lead to:
- SRY-Positive Males (XX): Individuals with an SRY-bearing X chromosome develop as males but remain sterile.
- SRY-Positive Females (XX): In exceptional cases, females carrying the SRY gene develop normally due to biased X chromosome inactivation, preventing the gene’s function.
