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What are the symptoms?
The main features found in the 22q11 deletion are numerous and affect every body system but the severity varies from person to person with two people from the same family not necessarily showing the same features to the same extent. These features include:
Heart problems (see entry, Heart Defects) which affect about seventy-five per cent of people with 22q11 deletion. The most common heart problems are: tetralogy of Fallot (a combination of four heart defects), interrupted aortic arch (failure of development of a section of the main artery supplying the body), ventricular septal defect (hole in the ventricle of the heart which allows blood to flow where it should not) and right aortic arch (instead of the usual left side).
Learning disabilities (see entry, Learning Difficulties) affect about sixty-five per cent people with 22q11 deletion and include: slow development of speech and language; poor concentration; and an inability to reach age appropriate milestones. The child may have difficulty at school with arithmetic, comprehension and problem solving, but may be particularly good at learning by rote and reading. The learning difficulties may be associated with a smaller than usual head size or rarely, by craniosynostosis (where the bones in the skull close before they should). ADHD - Attention Deficit Hyperactivity Disorder is more common than usual, making learning difficult. Early intervention can help reduce the problems.
Cleft palate (see entry, Cleft Lip and/or Palate) and velopharyngeal insufficiency are found in around sixty per cent of people with 22q11 deletion. The palate (or roof of the mouth) closes off the nose from the back of the mouth during speech and can contribute to a delay in speech and language. Regurgitation through the nose during swallowing can also occur, although it is not very common. This effect on speech and swallowing is called velopharyngeal insufficiency (VPI). Problems that might occur include a cleft palate (where there is a hole in the palate) or a submucous cleft (where the roof of the mouth may look fine, but the muscles are not in the right position). Another problem which may be present is weakness and in-coordination of the muscles in the roof of the mouth. VPI also occurs in some patients because the adenoids are poorly developed or the base of the skull is shortened. VPI results in an excessively nasal sounding voice, and makes consonant sounds more difficult.
Speech problems (see entry, Speech and Language Impairment) are common with clefts or VPI but may also result from developmental delay, learning difficulties, or hearing difficulties which are caused by problems with the Eustachian tubes (which drain fluid from the ear). This can cause glue ear, middle ear infections which are made worse or more frequent than usual due to the immune deficiency, developmental delay or learning difficulties.
Feeding difficulties are common in infancy and early childhood because of the combination of cleft palate and/or VPI, and regurgitation of stomach contents into the gullet and mouth (gastro-oesophageal reflux). There may also be problems with chewing and swallowing solids (dysphagia) which may benefit from specialist help.
People with 22q11 deletion tend to have similar facial features including almond shaped eyes, elongated facial features often with flat cheek bones, a long, 'strong' nose with a relatively broad and prominent nasal bridge, small nostrils, and small jaw. The ears may be small, prominent, and folded over at the top. The fingers are thin, and tapering at the ends with small underdeveloped nails. These features become easier to identify as the child grows older.
As some degree of thymus or T-cell malfunction is frequent, children often have infections due to impaired immunity but it is unusual for it to fail completely, and the immune problems often improve with age.
The parathyroid glands in the neck may be underactive which causes low levels of calcium in the blood, called hypocalcaemia, and this may cause convulsions. These are unusual after infancy, even if the hypocalcaemia persists. The thyroid gland may be under or over active (see entry, Thyroid Disorders), and growth hormone deficiency occurs occasionally. Individuals with 22q11 should therefore have their growth monitored. Any slowing of growth may need to be checked for nutritional and hormone deficiencies.
Emotional responses may be immature so some children may have difficulty in making relationships with children of their own age, or sometimes they may avoid eye contact. Extremes of rapid mood swings or behaviour varying from quiet inactivity to hyperactivity, and unexpected temper outbursts may cause serious management difficulties. After childhood, depression and other psychiatric conditions, including schizophrenia, have been found to be somewhat commoner than in the general population.
Kidney problems (see entry, Kidney disease) are found in thirty-five per cent of people with 22q11 deletion. It is quite common for a kidney to be absent, contain cysts, or for one kidney to be smaller than the other although its condition generally doesn't get worse. However, even if a child does not seem to have a kidney problem, an ultrasound examination should be made to confirm this.
Bone and muscle problems are more common in people with 22q11 deletion than usual. Problems that can occur include: scoliosis (curvature of the spine), neck bone abnormal structures needing surgical treatment if causing neck pain or loss of function affecting the spinal cord, Sprengel's shoulder (where the shoulder blade is in a higher position than normal), talipes (club foot) (see entry, Lower Limb Abnormalities) and rheumatoid arthritis (see entry, Arthritis (Juvenile Idiopathic)).
Muscle tone is often reduced. A lack of muscle bulk is common, so the children appear to have a small build. Joints that can be extended more than usual (hypermobility) may result in complaints of leg pains on walking and exercise. Hernias of the abdominal wall can occur. Constipation is more common as the gut muscles don't work so well. Testicles may not descend at the normal age.
Eye abnormalities include coloboma (deficiency in a local spot of the eyeball's layers), some developmental differences from usual and small cataracts which are unlikely to need intervention.
Rarely, a laryngeal web may cause breathing difficulties from birth.
Background
| Inheritance patterns and prenatal diagnosis 
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