Information
Editors
Down's Syndrome
Essentials
- Health problems that are characteristic to Down syndrome (DS) should be identified early (particularly congenital heart anomalies, vision and hearing impairment, hypothyroidism and coeliac disease). This always involves multi-speciality hospital investigations.
- The monitoring of the health and treatment of illnesses in people with DS is the responsibility of the primary health care.
- Support services for intellectual and developmental disabilities have special expertise in, for example, matters concerning rehabilitation.
- The functional capacity and health of adults should be monitored regularly.
Epidemiology and aetiology
- The frequency of DS in the Western world is approximately 1 case in 600-900 live births.
- The life expectancy of individuals with DS is now often over 60 years.
- The cause of DS is in about 95% of cases trisomy 21, occasionally mosaicism and in about 1-2% of cases the cause is translocation, which may be inherited from the parents.
- See also Screening for Fetal Chromosomal Abnormalities: Screening for foetal chromosomal abnormalities
- Foetal chromosomal screening reveals 60-70% of Down syndromes.
- The family may wish to prepare themselves to welcome a disabled child or choose to terminate the pregnancy.
- The clinician needs to be able to give the family information about the syndrome and the services available for these children
- Most individuals with DS live an active life. Most of them do need, however, support from their loved ones also during adulthood.
- Find out about local sources concerning peer support and information on the experiences of individuals with DS and their families.
Growth
- Children with DS are shorter, and their head circumference is smaller, when compared with the general population. Growth charts for children with DS are available.
- DS is associated with a tendency to obesity. Contributing factors include dietary habits, inactivity and possible hypothyroidism.
- The target weight in DS should be the weight that is considered normal for healthy children of equal height.
- The use of antioxidants or large doses of vitamins does not enhance growth or development.
Development
- The development and maturing of the brain is delayed, especially around the cerebellum and frontal lobes.
- Problems with working memory, auditory memory, executive functions, attention and learning are very common.
- Almost all affected individuals have defective language skills.
- Motor skills are also slow to develop.
- The majority of individuals with DS are classified with moderate intellectual deficiency, but the degree of intellectual deficiency ranges from mild to severe.
- Affected females have lowered infertility and males are infertile.
Common health problems
- Health problems which are more prevalent than in the general population include
- congenital heart anomalies
- gastrointestinal atresias
- hearing and vision impairment
- leukaemia
- hypothyroidism
- coeliac disease
- musculoskeletal problems
- early-onset memory disease.
- All health issues should be diagnosed early and treated efficiently to ensure optimal treatment results.
Heart anomalies
- Congenital heart anomalies are observed in 40-50% of children with DS. The most common types are atrioventricular septal defect (AVSD), ventricular septal defect (VSD), patent ductus arteriosus (PDA) and Fallot's tetralogy (FT) .
- All children with DS should undergo echocardiography and an ECG examination during the first weeks of life.
- Common atrioventricular septal defect will, particularly in children with DS, lead to the development of pulmonary hypertension. Surgery is no longer feasible after pulmonary hypertension has developed. Sometimes surgery has to be performed before the age of 3 months, usually before the age of 6 months. The outcome of surgery is usually good; functional capacity improves, morbidity decreases and life expectancy increases.
- Antibiotic prophylaxis for endocarditis should be prescribed before all invasive procedures, including the removal of dental tartar. See Prevention of Bacterial Endocarditis.
- Due to laxity of connective tissues, mitral and aortic valve regurgitation may develop in early adulthood.
- Hypertension and coronary artery disease are rare.
Vision impairment
- Accommodative insufficiency is common in infants and small children. Bifocals will improve the child's near vision.
- Refractive errors, which are correctable with glasses, are encountered in over half of children and adolescents as well as in adults.
- Squint, amblyopia and keratoconus are more common than in the general population.
- Congenital cataracts are encountered, and lens opacity is frequently noted from the age of 20-30 onwards. With increasing age cataracts will become more common.
- Examination by an ophthalmologist is recommended, starting at the age of 6 months and continued regularly throughout life.
Hearing impairment
- About 60% of children with DS are found to have hearing impairment.
- The most common problem is hearing impairment due to glue ear.
- The testing of hearing in children with DS should commence during the first year of life, and continue thereafter yearly throughout childhood, in order to optimise speech development.
- In adults, a hearing test is recommended every 3 years since deterioration of hearing often starts already at the age of 20-30 years.
- A hearing aid during childhood facilitates language learning. Good results have also been gained with cochlear implants.
Central nervous system disorders
- About 3% of children have infantile spasms. The incidence of epilepsy increases to about 30% in later life.
- The investigation and treatment should follow locally relevant guidelines.
- As many as half of pre-school children with DS have sleep apnoea, which results from both structural and central problems.
- Memory diseases start significantly earlier than in the general population. After the age of 40 every individual with DS will exhibit neuropathological changes of Alzheimer's disease. The ability to cope with daily activities, employment and leisure pursuits will gradually start to deteriorate from about the age of 40 onwards. Monitoring these activities will assist in the diagnosis of memory diseases.
- Cerebral infarcts are common.
Immune system disorders
- DS is associated with disorders of the immunological system.
- The risk of leukaemia in early childhood is increased, particularly among children who experienced a leukaemoid reaction (leucocytosis, presence of myeloblasts and hepatosplenomegaly) during the neonatal period or in infancy (incidence 10%) the cause of which is transient bone marrow dysfunction.
- The susceptibility to infections is increased. The incidence of respiratory tract and ear infections is high. Mucous discharge, congestion and general "chestiness" more often result from narrow airways and an abnormal structure of the mucous membranes than from an infection.
- The incidence of autoimmune diseases, such as thyroiditis, coeliac disease and diabetes, is increased. Psoriasis, alopecia areata (spot baldness) and rheumatoid arthritis are also more common than among the general population.
Hypothyroidism
- Hypothyroidism is common and the incidence increases with age. The most common cause is autoimmune thyroiditis.
- A high prevalence of subclinical hypothyroidism is a special feature of DS: TSH concentration is elevated, but free T4 is normal in up to 30% of individuals. In one third of cases, subclinical hypothyroidism resolves spontaneously but may also precede thyroid disease.
- Monitoring cannot rely on the clinical picture; monitoring THS every 2 years throughout life is recommened.
Gastrointestinal problems
- Congenital anomalies, especially atresias, are common and require early surgery.
- Constipation is very common and is managed with diet and, if necessary, medication. Painful anal mucosal damage may lead to defecation related anxiety and worsen constipation.
- Hirschprung's disease 12 must be kept in mind as a possible cause of constipation.
- Coeliac disease has been found in 6-7% of those screened, but symptoms are present in only 0.8-3% of individuals with DS. Screening has been suggested for all children with DS. Testing is indicated at the emergence of the slightest symptoms; determination of anti-endomysial and anti-transglutaminase antibodies and, if necessary, small bowel biopsy Coeliac Disease.
- About one fifth will develop gallstones already in childhood. Surgery is not always needed. Small stones (gravel) within the gallbladder may disappear spontaneously.
Dental and oral health
- DS renders the individual more susceptible to periodontal disease. Since this is due to immunological abnormalities, good oral hygiene is only partially effective as a preventive measure. Good diet plays an important role in oral health. Regular check-ups by a dentist or dental hygienist are important.
- Antibiotic prophylaxis must be prescribed for those with a heart defect. See Prevention of Bacterial Endocarditis.
Musculoskeletal problems
- Joints are hypermobile and muscles hypotonic.
- The treatment for flat feet usually only requires sturdy shoes, and shoe inserts may be used if necessary.
- Dislocations of the hip are common in children under the age of 10 years of age and patellar dislocations even at a later age. An orthopaedic surgeon should be consulted if necessary.
- There is no need to restrict the amount of exercise or sports. Regular physical exercise increases well-being, improves physical condition and helps in weight management.
- The gap between the topmost vertebrae is abnormal and often hypermobile in 10-40% of individuals with DS. About 2% exhibit symptoms of spinal cord compression. The symptoms include problems with walking and using hands, neck pain and incontinence. These patients should be referred for neurological or neurosurgical investigations.
Behaviour and mental health
- Autistic features are found in up to 10% of individuals with DS.
- Severe mental health and behavioural problems are seen in 18-38% of children with DS, which is still less than in children with other developmental disabilities.
- Depression is 2-3 times more common than in those affected by other developmental disabilities. The symptoms include withdrawal, tearfulness, loss of appetite, sleep disorders and mood swings. Hypothyroidism, sleep apnoea and incipient memory disease should be considered in differential diagnosis.
- Rehabilitation should be individualised and target-oriented.
- Rehabilitation is based on a programme drawn up by a multidisciplinary team together with the parents. The programme should be reviewed every 1-3 years.
- Early intervention to augment communication, such as the introduction of sign language to support speech, enhances language development. Signs to be used are taught both to the parents and others close to the child. The upbringing of the child must be clear and consistent.
- Individual therapy (often speech therapy, but also physiotherapy, occupational therapy and/or music therapy as appropriate) is often the recommended type of rehabilitation.
- Day care may form a part of rehabilitation.
- Various grants and allowances may be available.
- Individualised schooling is usually carried out in small groups under the guidance of an assistant. In some cases, education is possible in mainstream schools in the lower forms. Legislation regarding school entry age and the duration of compulsory education shows country-specific variation. In Finland, children with DS have the possibility to participate in preschool education for a period of 2 years, starting at the age of 5-6 years, and they have an extended compulsory education of 11 years.