Genetic Disorders

Klinefelter's syndrome is a genetic disorder that affects males. It is characterized by an additional X chromosome, resulting in the karyotype 47,XXY. This chromosomal condition leads to a range of symptoms and physical traits.

1. Masculine Development: Individuals with Klinefelter's syndrome typically have male physical characteristics, such as increased height.
2. Gynaecomastia: A significant number of these individuals develop gynaecomastia, which is the enlargement of breast tissue.
3. Sterility: One of the common consequences of Klinefelter's syndrome is infertility due to underdeveloped testicles and resulting low levels of testosterone.

The question asks for the disorder where there is overall masculine development along with gynaecomastia and sterility. Let's evaluate the given options:

• Turner's syndrome: This affects females and is characterized by the presence of a single X chromosome (45,X). Symptoms include short stature and infertility but not masculine development.
• Edward syndrome: Also known as Trisomy 18, this condition causes severe developmental delays and malformations but does not relate to masculine development or gynaecomastia.
• Down's syndrome: Resulting from Trisomy 21, this syndrome leads to intellectual disability and distinct facial features, without the traits described in the question.
• Klinefelter's syndrome: As discussed, this syndrome fits the description perfectly.

Hence, the correct answer is Klinefelter's syndrome.