Patient's question:
I have a classmate who was quite introverted since a young age and had relatively less hair. When we went through the second stage of puberty, he seemed to show no changes at all, unlike us who grew facial hair. People thought he was like a good child. Recently, I heard that he went to the hospital for a check-up and was diagnosed with Down syndrome.Doctor's answer:
Hello, Klinefelter syndrome, also known as XYY chromosome syndrome, is a condition in which individuals have 47, XYY chromosomes. It was first discovered in 1961. In their sex chromosomes, the X chromosome is negative, while the Y chromosome is double-positive. The karyotype is 47, XYY. The extra Y chromosome is caused by the failure of chromosome separation during the meiosis of the father's germ cells.