22q11 deletion (di George syndrome)
Di George syndrome is a severe genetic disorder that is noticeable at birth. At the very worst, it can result in heart defects, learning difficulties, a cleft palate and potentially many other problems. However, not everyone is severely affected and most people with the condition will live normal life spans.
In almost all cases of di George syndrome, these symptoms and features result from a missing piece of chromosome – a genetic fault, or mutation, called 22q11 deletion (see the box, below left, for an explanation).
The 22q11 deletion can potentially result in many different combinations of symptoms (syndromes), and di George syndrome is just one possible consequence.
Each person with di George syndrome is affected differently and the symptoms can vary widely.
This page covers:
What are the main features of di George syndrome?
How is di George syndrome diagnosed?
What are the chances of my next child having it?
What help and support is available?
What are the main features of di George syndrome?
Di George syndrome can potentially cause many different problems affecting various areas of the body.
The main features are described below, but bear in mind that the severity of these problems varies from person to person and some people with the syndrome will only experience a few of them.
Heart problems
It's common for children with di George syndrome to have heart abnormalities from birth, such as a hole in the heart or a problem with the main artery leaving the heart (the aorta).
Many children will have four specific structural abnormalities of the heart, collectively known as 'tetralogy of Fallot':
- pulmonary stenosis – narrowing between the right heart chamber and the main blood vessel (pulmonary artery) that carries blood from the heart to the lungs
- ventricular septal defect – a hole between the right and left pumping chambers (ventricles) of the heart
- over-riding aorta – the entrance to the large blood vessel that takes blood away from the heart to the rest of the body (aorta) is next to the ventricular septal defect, allowing oxygen-poor blood to flow through it
- thick right ventricle – the heart has to work harder to pump blood through the narrowed pulmonary artery, causing the muscle to thicken
Learn more about congenital heart disease.
A doctor will carry out an echocardiogram (ultrasound of the heart) to check if your child has these heart problems. Surgery may be needed to correct some of them.
Learning difficulties
Commonly, children with di George syndrome will have slow development of speech and poor concentration, and may struggle with maths and problem solving.
Attention deficit hyperactivity disorder (ADHD) and autistic spectrum disorder are fairly common, which makes learning even more difficult.
The earlier any learning difficulties are noticed the better, as prompt treatment can reduce their impact and allow parents to organise any special help needed at nursery or school.
Problems with the mouth, feeding and hearing
Some children with di George syndrome have a cleft palate (hole in the roof of their mouth) or a problem with the surrounding mouth muscles. A few will also have a cleft lip (split in the upper lip). Read more about cleft lip and palate problems.
These problems can result in:
- difficulty with speech and language and a 'nasal' voice
- feeding problems – they may find it hard to chew and swallow solids (read more about dysphagia), may occasionally regurgitate food through their nose when swallowing, and typically do not put on much weight
- an ear infection such as glue ear, which may lead to temporary hearing loss
Appearance
Children with di George syndrome tend to have the following features:
- wide-set almond-shaped eyes
- a long nose with a broad nasal bridge and small nostrils
- a small jaw
- small, low-set ears that are folded over at the top
- thin, tapering fingers with underdeveloped nails
- a cleft lip
- a cleft palate
These features will become easier to spot as the child gets older.
Infections
Children with di George syndrome generally have weak immune systems because of a problem with the thymus gland – a gland in the neck that produces cells needed to fight invading germs. It means they may be susceptible to recurrent infections such as oral thrush and pneumonia.
However, immune system problems often improve with age.
Hormones and growth
Many children with di George syndrome also have an underactive parathyroid gland, known as hypoparathyroidism.
There are four tiny parathyroid glands, each the size of a grain of rice, in the neck behind the thyroid gland. They produce parathyroid hormone to help control the levels of calcium, phosphorus and vitamin D within the bones and blood.
An underactive gland causes low levels of calcium in the blood. This means a child with di George syndrome may experience seizures (fits), although these are unusual after infancy.
Some children may also be short for their age because of a growth hormone deficiency, and have an underactive thyroid gland.
Emotional and mental health problems
Children with di George syndrome may find it difficult to make friends with children their own age and may struggle making eye contact.
They may have rapid mood swings, swinging from quietness to hyperactivity, and have unexpected temper tantrums.
Teenagers with di George syndrome are more likely to develop depression and other psychiatric conditions, including schizophrenia.
Bone and muscle problems
Bone and muscle problems are fairly common in people with di George syndrome.
Problems that can occur include:
- abnormalities of the spine, such as scoliosis (a curved spine)
- a high shoulder blade
- club foot
- rheumatoid arthritis
- cramp-like muscle spasms in the hands and fingers, or muscle twitches in the face, throat or arms
- weak muscles, resulting in hernias and constipation (because gut muscles don't work as well)
- lack of muscle mass (children tend to have a small build)
- over-flexible joints (joint hypermobility)
- undescended testicles
Eye problems
Possible eye problems include a hole in the iris of the eye, known as coloboma, and small cataracts – although these probably won't need treating. Read more about coloboma and childhood cataracts.
Kidney problems
It is quite common for someone with di George syndrome to have a missing kidney, or for one kidney to be smaller than the other. An ultrasound scan will pick this up.
This shouldn't cause any problems and no treatment is necessary.
How does the mutation happen?
In most cases of di George syndrome, the missing piece of chromosome would already have been missing from the egg or sperm from which the baby was conceived. It's fairly common for errors like this to happen by chance when DNA is copied to make sperm and eggs, and you cannot prevent it.
In a small number of cases, the 22q11 deletion will have been passed on to the child by one of the parents who already had the mutation.
How is di George syndrome diagnosed?
The piece of missing chromosome that causes di George syndrome is so small that it cannot be seen under a microscope.
If a doctor suspects di George syndrome in an unborn baby, they will order a special test called the FISH test (fluorescence in situ hybridisation) to be carried out on a sample of the fluid surrounding the baby (an amniocentesis). The FISH test shows whether or not the region of chromosome 22 is present. If only one copy of chromosome 22 'lights up' with the fluorescent DNA dye, rather than both copies, the test is positive.
If a doctor suspects an adult or child has di George syndrome, the FISH test is carried out on a blood sample.
However, the FISH test doesn't pick up every case of di George syndrome. A small minority of people with the syndrome will not test positive, and the diagnosis will be solely made on the characteristic features and symptoms.
What are the chances of my next child having it?
An affected parent has a 50% chance of passing on the condition to their child. This applies in each pregnancy. If neither parent is missing the piece of chromosome, there's still a 1-2% chance they will have a further child with the syndrome.
The earliest an unborn baby can be tested in pregnancy is at 11 weeks, by chorionic villus sampling (CVS), so booking antenatal care early is essential. Testing is also available by amniocentesis from 16 weeks onwards.
Find out more about genetic testing and counselling.
What help and support is available?
Your child will have regular tests from infancy onwards, including:
- hearing tests and eye examinations for long-sightedness
- medical tests of their immune system
- kidney and heart scans and tests
Before they start school, your child's developmental progress and speech and language development should be carefully assessed. If your child has a learning disability, their educational needs can be met either in a mainstream school with extra support, or in a special school. Read more about education for children with learning disabilities.
A physiotherapist can help with any physical problems – for example, shoe inserts (orthoses) may help your child's leg pains. Read more about physiotherapy.
Surgery may be needed to correct any serious problems, such as heart surgery or an operation to reduce the amount of air escaping through their nose (if your child's speech is very nasal).
You may find it useful to discuss your concerns with a social worker, psychologist or counsellor, whom you can contact directly or via your doctor. Read more about caring for a disabled child and childcare options for disabled children.
Self-help groups such as the Max Appeal and The 22q11 Group may also be a good source of information and support.
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