Almost all girls with Turner syndrome will grow up to be shorter than average, with underdeveloped ovaries.
Girls with Turner syndrome also have distinctive features and associated health conditions, some of which may be apparent from birth.
They may be born with swollen hands and feet, caused by a build-up of excess fluid (lymphoedema) in the surrounding tissues, but this usually clears soon after birth.
Other features that may have developed in the womb include:
Babies with Turner syndrome may grow at a normal rate until they're 3 years old. After this, their growth slows down.
At puberty, usually between 8 and 14 years, a girl with Turner syndrome will not have the normal growth spurt, even with female oestrogen hormone replacement (HRT).
Girls with Turner syndrome are typically short in relation to the height of their parents. On average, adult women with untreated Turner syndrome are 20cm (8in) shorter than adult women without the syndrome. Treatment with additional high-dose growth hormone reduces this difference by about 5cm (about 2in) on average.
Read more about growth hormone treatment in Turner syndrome.
Ovaries are the pair of female reproductive organs that produce eggs and sex hormones. During puberty, a girl's ovaries usually begin to produce the sex hormones oestrogen and, once fully mature, progesterone. These trigger periods to begin.
Around 90% of girls with Turner syndrome don't produce enough of these sex hormones, which means:
Even though many women with Turner syndrome have undeveloped ovaries and are infertile, their vagina and womb develop normally. This means they're able to have a normal sex life following treatment with female hormones.
Most girls need hormone replacement therapy (HRT) with oestrogen from around 10 to 12 years of age to begin breast development, and about 3 years later with added progesterone to bring on monthly periods.
A minority (10%) of girls with Turner syndrome experience some physical changes naturally during puberty, but only a very small number (1%) become pregnant naturally.
There are many other symptoms or characteristics that can affect girls and women with Turner syndrome.
Turner syndrome is often associated with a number of other health conditions, including:
Most girls with Turner syndrome have good language and reading skills. However, some have behavioural, social and specific learning difficulties.
About a third of girls with Turner syndrome have problems understanding social relationships because of the way their brain develops.
This can make it difficult to sustain friendships and leads to relationship problems in later life, both at home and at work.
Spatial awareness is the ability to understand where you are in relation to objects or other people.
More than 8 out of 10 females with Turner syndrome have difficulty understanding spatial relationships. This may cause problems when learning to drive or following directions on a map.
A similar number have some degree of difficulty learning or understanding maths. This is known as dyscalculia.
Typically, girls with Turner syndrome will go through a phase in childhood that involves:
Attention and hyperactivity problems usually begin when the girl is a toddler but may not be a serious problem until the girl starts school at 4 or 5. Girls with Turner syndrome may have difficulty settling in class.
Medicines used to treat attention deficit hyperactivity disorder (ADHD) may not be as effective in cases of Turner syndrome.
The physical hyperactivity usually reduces around the time the girl starts secondary school at 11 years of age, although problems with inattention can last longer, into the teens.