Video Transcript
Turner syndrome is an example of a syndrome caused by chromosomal abnormalities. How is Turner syndrome caused? (A) Turner syndrome is caused by the loss or change in structure of a Y chromosome. (B) Turner syndrome is caused by a large change in the structure of chromosome 13. (C) Turner syndrome is caused by the gain of a complete Y chromosome. Or (D) Turner syndrome is caused by the loss or change in the structure of an X chromosome.
This question asks about the cause of a disorder called Turner syndrome. You may recall that a chromosomal abnormality is a change in the number or structure of chromosomes. In general, humans have 46 chromosomes, which form 23 pairs. There are two types of chromosomes. The sex chromosomes are the last pair of chromosomes, and these are the ones that are responsible for determining the biological sex of the person. In general, biological females have two X chromosomes, while biological males have one X and one Y chromosome. The other 22 chromosomes are numbered one to 22 and are called autosomes.
Turner syndrome is a disorder that arises from a chromosomal abnormality in the sex chromosomes. This condition affects biological females. People with Turner syndrome may experience traits associated with sexual development, such as decreased production of estrogen, loss of ovary function, and infertility. They may also have congenital heart and kidney problems and stunted growth.
So what chromosomal abnormality causes Turner syndrome? Well, as we mentioned earlier, biological females typically have two X chromosomes, which we represent as XX. In people with Turner syndrome, one X chromosome is partially or completely missing. We represent this missing chromosome with an O, so people with Turner syndrome are said to have XO sex chromosomes. Remember, this O is not a chromosome. It represents the absence of one.
Now that we’ve covered a little bit about Turner syndrome, we can answer our question. The correct answer is option (D). Turner syndrome is caused by the loss or change in the structure of an X chromosome.