Turner's Syndrome

Characteristics/Phenotypes

Turner's syndrome is a genetic disorder that affects females. Usually, a female has two X chromosomes; in females with Turner's syndrome, one of these chromosomes is missing or abnormal. Other names for Turner's syndrome include monosomy X, 45X and Ullrich-Turner syndrome.

The characteristic of the disease is mainly depending on the age of the girl or woman affected.

 Babies born with Turner syndrome often have swollen hands and feet caused by lymphoedema. Prominent thick neck tissue, swelling of the neck (cystic hygroma) and being a small baby.

The two most common characteristics of Turner syndrome are:

• short height
• ovaries that do not function

These two characteristics affect more than nine out of ten females with Turner syndrome.  Babies with Turner syndrome are usually a normal height until the age of three. After this age, they will have a lower-than-average growth rate.

At puberty, a girl with Turner syndrome will not have the normal growth spurt. Puberty usually happens in girls aged between eight and thirteen. Without treatment, someone with Turner syndrome will usually grow to around 136-147cm (4ft 6in to 4ft 10in). On average, adult women with untreated Turner syndrome are 20cm (8in) shorter than adult women without Turner syndrome. Treatment with growth hormones can reduce this difference.

Ovaries are the pair of reproductive organs in females that produce eggs and sex hormones. During puberty, a girl's ovaries usually begin to produce the sex hormones oestrogen and progesterone. However, most girls who have Turner syndrome will not produce these sex hormones, which means that they:

• may not start their periods naturally as other girls do  
• may not fully develop breasts
• may be infertile (unable to conceive a baby)

As well as short height and non-functioning ovaries, there are many other symptoms or characteristics that can affect girls and women with Turner syndrome. Some of these are listed below.

Symptoms that affect appearance include: 

• a particularly short, wide neck (webbed neck)
• a broad chest and widely spaced nipples
• arms that turn out slightly at the elbows
• a low hairline
• abnormalities of the mouth, which can cause problems with the teeth
• a large number of moles
• small, spoon-shaped nails 
• a short fourth finger or toe
• eyes that slant downwards
• an eye problem (cataract, ptosis)
• low-set ears 
• hearing loss, which can develop in later life, is often more severe and develops earlier than the normal age-related decline in hearing

Most girls with Turner syndrome have good language and reading skills. However, some have behavioural, social and specific learning difficulties that are often overlooked by doctors that can cause great anxiety to the parents. They include: 

• problems with social intelligence 
• problems with spatial awareness and numeracy
• attention and hyperactivity problems

Frequency
This condition occurs in about 1 in 2,000-2,500 female births worldwide, but is much more common among pregnancies that do not survive to term (miscarriages and stillbirths).

Diagnosis

The condition may be diagnosed at various life stages including:

·         Before birth (prenatally) – usually if an amniocentesis has been performed or abnormalities are seen during an ultrasound

·         At birth – due to certain physical features

·         In childhood – when the young girl doesn’t grow at a similar rate to her peers

·         During the teenage years – when puberty fails to arrive

·         In adulthood – during investigations for infertility.

Turner’s syndrome is diagnosed using a number of tests including:

·         Amniocentesis and chorionic villus sampling (before birth)

·         Karyotyping

·         Clinical history

·         Physical examination

·         Psychological and educational assessment

·         Blood tests and chromosome analysis Genetic tests.

Cause/s

Turner syndrome is typically caused by what is called nondisjunction. If a pair of sex chromosomes fails to separate during the formation of an egg (or sperm), this is referred to as nondisjunction. When an abnormal egg unites with a normal sperm to form an embryo, that embryo may end up missing one of the sex chromosomes (X rather than XX). As the embryo grows and the cells divide, every cell of the baby's body will be missing one of the X chromosomes.

The abnormality is not inherited from an affected parent (not passed down from parent to child) because women with Turner syndrome are usually sterile and cannot have children.

In about 20 percent of Turner syndrome cases, one X chromosome is abnormal. It may be shaped like a ring, or missing some genetic material.

About 30 percent of girls with the disorder are only missing the X chromosome in some of their cells. This mixed chromosome pattern is known as mosaicism. Girls with this pattern may have fewer symptoms because they still have some normal (XX) cells.

Treatments/Therapies

Hormone replacement therapy is the best way to treat this disorder. Teenagers are treated with growth hormone to help them reach a normal height. They may also be given low doses of androgens (male hormones which females also produce in small quantities) to increase height and encourage normal hair and muscle growth. Some patients may take the female hormone estrogen to promote normal sexual development.

Babies born with a heart murmur or narrowing of the aorta may need surgery to correct the problem. A heart expert (cardiologist) will assess and follow up any treatment necessary.

Girls who have Turner syndrome are more likely to get middle ear infections. Repeated infections may lead to hearing loss and should be evaluated by the pediatrician. An ear, nose and throat specialist (ENT) may be involved in caring for this health issue. Almost all women are infertile, but pregnancy with donor embryos may be possible.

Recommendations/Advices

Remember that Regular health checks are very important.

Special clinics for the care of girls and women who have Turner syndrome are available in some areas, with access to a variety of specialists.

Early preventive care and treatment is very important.

Having appropriate medical treatment and support allows a woman with Turner syndrome to lead a normal, healthy and happy life.

References

http://www.nhs.uk/Conditions/Turners-syndrome/Pages/Symptoms.aspx

http://learn.genetics.utah.edu/content/disorders/whataregd/turner/

http://www.medicinenet.com/turner_syndrome/page2.htm

http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Turner's_syndrome

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