Turner syndrome is characterized by clinical manifestations of varying intensity depending on the lack of genetic material. A completely missing X chromosome causes more symptoms than a small part of the missing X chromosome or a case of mosaicism.

Here are the observable symptoms:

• Small size from birth and even before, but the slowdown in growth compared to other children is especially noticeable from 4 years old. Adult height is on average 20 cm shorter than the average, 1,45 m.
• The absence of development at the time of puberty, because of anomalies of the ovaries: the breasts do not develop and the rules do not appear. In some cases, however, rules may appear.
• Infertility is most often present. Only 1 to 2% of women with Turner syndrome can be pregnant.
• On observe swelling of feet and hands at birth.
• The neck is said to be “webbed”.
• There are deformations at the elbows.