Which genetic disorder is caused by complete or partial monosomy of the X chromosome in females?
Solution
Correct Answer: Option B
The genetic disorder caused by complete or partial monosomy of the X chromosome in females is Turner syndrome.
- Turner syndrome occurs when a female has only one complete X chromosome or has a partial loss of one X chromosome, resulting in a 45,X karyotype or mosaic variants involving the loss of part of the X chromosome.
- This monosomy leads to a variety of clinical features including short stature, gonadal dysgenesis (streak ovaries), infertility, cardiovascular abnormalities, and certain characteristic physical features such as a webbed neck, low-set ears, and lymphedema.
- Turner syndrome is unique to females, as it involves the absence or structural abnormality of one of the two female sex chromosomes.
- In contrast:
- Klinefelter syndrome (Option 1) involves males with an extra X chromosome (47,XXY).
- Triple X syndrome (Option 3) involves females with an extra X chromosome (47,XXX).
- Fragile X syndrome (Option 4) is a genetic disorder associated with a mutation in the FMR1 gene on the X chromosome, leading to intellectual disability but not monosomy.
In summary, Turner syndrome is characterized by the presence of only one functional X chromosome, leading to monosomy X, which distinguishes it from other sex chromosome abnormalities.
Reference: Thompson & Thompson Genetics in Medicine, 8th Edition, Chapter 10, Pages 320-325
- Turner syndrome occurs when a female has only one complete X chromosome or has a partial loss of one X chromosome, resulting in a 45,X karyotype or mosaic variants involving the loss of part of the X chromosome.
- This monosomy leads to a variety of clinical features including short stature, gonadal dysgenesis (streak ovaries), infertility, cardiovascular abnormalities, and certain characteristic physical features such as a webbed neck, low-set ears, and lymphedema.
- Turner syndrome is unique to females, as it involves the absence or structural abnormality of one of the two female sex chromosomes.
- In contrast:
- Klinefelter syndrome (Option 1) involves males with an extra X chromosome (47,XXY).
- Triple X syndrome (Option 3) involves females with an extra X chromosome (47,XXX).
- Fragile X syndrome (Option 4) is a genetic disorder associated with a mutation in the FMR1 gene on the X chromosome, leading to intellectual disability but not monosomy.
In summary, Turner syndrome is characterized by the presence of only one functional X chromosome, leading to monosomy X, which distinguishes it from other sex chromosome abnormalities.
Reference: Thompson & Thompson Genetics in Medicine, 8th Edition, Chapter 10, Pages 320-325
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