Xiao Lin is 16 years old, is a junior high school students in our city, and other male students in the class compared to his obviously different, voice and high and pointed, the skin is good and girls, students are called him is “beautiful boy”. Xiao Lin was very inferior to this, but Xiao Lin’s father was very nervous, he found that Xiao Lin not only did not develop genitalia, but also small testicles, only the size of peanuts, I received them in the clinic. After a physical examination of Xiao Lin, it was found that not only were his testicles small, but also his male secondary sexual characteristics were not obvious. After a series of laboratory tests, it was confirmed that Xiao Lin belonged to a kind of congenital chromosomal abnormality – Creutzfeldt-Jakob syndrome. What is Creutzfeldt-Jakob syndrome? It is also known as congenital testicular dysplasia syndrome, first discovered and described by Klinfelter in 1942, so it is also called Kirschner syndrome. It is one of the common genetic disorders with abnormal number of sex chromosomes and one of the most common forms of male hypogonadism. The normal male karyotype is 46, XY, while Kobayashi’s chromosome is 47, XXY, which means he has one more X chromosome than normal males. Most of these patients have no abnormalities in childhood and gradually show abnormalities in adolescence and adulthood. The testicles are very small, only the size of beans or peanuts, about half of them have female breast development, male secondary sexual characteristics are abnormally developed; the stature is taller, the limbs are slender, the shoulders are narrower, the pelvis is similar to female, there is more subcutaneous fat, the muscles are not developed, there is a tendency of obesity, the voice is sharp and thin, there are no throat knots, the beard and body hair are not obvious or sparse, the pubic hair is often female distribution, the external genitalia are male type, the penis is normal or short, most Most of the patients can have an erection, some can ejaculate, although they can also have conjugal sex, but the strength and duration of the erection cannot be satisfactory, and the time of decline of sexual ability is also earlier than normal. The treatment principle of Creutzfeldt-Jakob syndrome is early detection, early diagnosis and treatment, and early application of androgen replacement therapy. Hormone replacement therapy is important for promoting the development of secondary sexual characteristics, making them masculine, improving sexual function, improving mental status and life adaptation ability, and relieving low self-esteem to improve patients’ confidence. However, patients with Creutzfeldt-Jakob syndrome have no sperm in their semen and are not fertile, so no treatment can restore their fertility. For couples who want to have children, artificial insemination with another person’s sperm or adoption of a child can be practiced as long as the woman is healthy and her fertility is normal after examination.