- Health aspects of Down syndrome
Down syndromeis a genetic disease resulting from the presence of all or part of an extra 21st chromosome ( trisomy 21). The medical consequences of this extra genetic material are highly variable and may affect the function of any organ system or bodily process. The health aspects of Down syndrome encompass anticipating and preventing effects of the disease, recognizing complications of the disorder, managing individual symptoms, and assisting the individual and his/her family in coping and thriving with the illness. [American Academy of Pediatrics. Committee on Genetics. "American Academy of Pediatrics: Health supervision for children with Down syndrome." Pediatrics. 2001 Feb;107(2):442-9. PMID 11158488] The most common manifestations of Down syndrome are the characteristic facial features, cognitiveimpairment, congenital heart disease, hearing deficits, short stature, and Alzheimer's disease. Other serious, but less common illnesses include leukemia, immune deficiencies, and epilepsy.
There are benefits as well as challenges: People with Down syndrome have a reduced risk of developing most kinds of cancer,
atherosclerosis, or diabetic retinopathy. [http://news.yahoo.com/s/nm/20080102/hl_nm/cancer_down_dc]
Down syndrome can result from several different genetic mechanisms. This results in a wide variability in individual symptoms due to complex
geneand environment interactions. Prior to birth, it is not possible to predict the symptoms that an individual with Down syndrome will develop. Some problems are present at birth, such as certain heart malformations. Others become apparent over time, such as epilepsy.
Endocrinology and hematology
Individuals with DS are at increased risk for dysfunction of the
thyroid gland, an organ which helps control metabolism. Low thyroid ( hypothyroidism) is most common, occurring in almost a third of those with DS. This can be due to absence of the thyroid at birth ( congenital hypothyroidism) or due to attack on the thyroid by the immune system. [Karlsson B, Gustafsson J, Hedov G, Ivarsson SA, Anneren G. "Thyroid dysfunction in Down's syndrome: relation to age and thyroid autoimmunity." Arch Dis Child. 1998 Sep;79(3):242-5. PMID 9875020] Reproductionis also affected by DS. Women with DS are less fertile and often have difficulties with miscarriage, premature birth, and difficult labor. However, women with DS are capable of having children without the extra chromosome 21 of DS. [Bovicelli L, Orsini LF, Rizzo N, Montacuti V, Bacchetta M. "Reproduction in Down syndrome." Obstet Gynecol. 1982 Jun;59(6 Suppl):13S-7S. PMID 6211644] Men with DS are almost uniformly infertile, exhibiting defects in spermatogenesis. [Johannisson R, Gropp A, Winking H, Coerdt W, Rehder H, Schwinger E. "Down's syndrome in the male. Reproductive pathology and meiotic studies." Hum Genet. 1983;63(2):132-8. PMID 6220959]
Hematologic malignancies such as leukemia are more common in children with DS. In particular, the risk for
acute lymphoblastic leukemiais at least 10 times more common in DS and for the megakaryoblasticform of acute myelogenous leukemiais at least 50 times more common in DS. Transient leukemiais a form of leukemia which is rare in individuals without DS but affects up to 20 percent of newborns with DS. This form of leukemia is typically benign and resolves on its own over several months, though it can lead to other serious illnesses. ["Transient leukaemia--a benign form of leukaemia in newborn infants with trisomy 21." Br J Haematol. 2003 Mar;120(6):930-8. Review. PMID 12648061] In contrast to hematologic malignancies, solid tumor malignancies are less common in DS, possibly due to increased numbers of tumor suppressor genes contained in the extra genetic material. [Hasle H, Clemmensen IH, Mikkelsen M. "Risks of leukaemia and solid tumours in individuals with Down's syndrome." Lancet. 2000 Jan 15;355(9199):165-9. PMID 10675114]
Gastrointestinal and growth
Down syndrome increases the risk of
Hirschsprung's disease, in which the nerve cells that control the function of parts of the colon are not present. [Ikeda K, Goto S. "Additional anomalies in Hirschsprung's disease: an analysis based on the nationwide survey in Japan." Z Kinderchir. 1986 Oct;41(5):279-81. PMID 2947399] This results in severe constipation. Other congenital anomalies occurring more frequently in DS include duodenal atresia, annular pancreas, and imperforate anus. Gastroesophageal reflux diseaseand celiac diseaseare also more common among people with DS. [Zachor DA, Mroczek-Musulman E, Brown P. "Prevalence of celiac disease in Down syndrome in the United States." J Pediatr Gastroenterol Nutr. 2000 Sep;31(3):275-9. PMID 10997372]
Growth parameters such as height, weight, and head circumference are smaller in children with DS than with individuals of the same age. Adults with DS tend to have
short stature— the average height for men is 5 feet 1 inch (157 cm) and for women is four feet 9 inches (144 cm). [Cronk C, Crocker AC, Pueschel SM, Shea AM, Zackai E, Pickens G, Reed RB."Growth charts for children with Down syndrome: 1 month to 18 years of age." Pediatrics. 1988 Jan;81(1):102-10. PMID 2962062] Individuals with DS are also at increased risk for obesity as they age. [Rubin SS, Rimmer JH, Chicoine B, Braddock D, McGuire DE. "Overweight prevalence in persons with Down syndrome." Ment Retard. 1998 Jun;36(3):175-81. PMID 9638037]
Persons with down syndrome are at higher than normal risk for atlanto-axial instability, probably due to ligamental laxity. Periodic screening, with cervical x-rays, is recommended to identify this abnormality.
The neurologic consequences of DS manifest early in life. Infants with Down Syndrome have a decreased
muscle toneand are more flexible. Mental retardation becomes apparent as individuals with DS grow and develop — sitting, walking, and talking are typically delayed. Children and adults with DS are at increased risk for developing epilepsy. [Goldberg-Stern H, Strawsburg RH, Patterson B, Hickey F, Bare M, Gadoth N, Degrauw TJ."Seizure frequency and characteristics in children with Down syndrome." Brain Dev. 2001 Oct;23(6):375-8. PMID 11578846] [Menendez M. "Down syndrome, Alzheimer's disease and seizures." Brain Dev. 2005 Jun;27(4):246-52. Review. PMID 15862185] The risk for Alzheimer's disease is increased in individuals with DS, with 10-25% of individuals with DS showing signs of AD before age 50, up to 50% with clinical symptoms in the sixth decade, and up to 75% in the 7th decade. This sharp increase in the incidence and prevalence of dementia may be one of the factors driving the decreased life expectancy of persons with Down Syndrome.
Ophthalmology and otolaryngology
Eye disorders are more common in people with DS. Almost half have
strabismus, in which the two eyes do not move in tandem. Refractiveerrors requiring glasses or contacts are also common. Cataracts (opacity of the lens) and glaucoma(increased eye pressures) are also more common in DS. [Caputo AR, Wagner RS, Reynolds DR, Guo SQ, Goel AK. "Down syndrome. Clinical review of ocular features." Clin Pediatr (Phila). 1989 Aug;28(8):355-8. PMID 2527102] Hearing lossaffects more than half of individuals with DS, due to multiple factors. [Roizen NJ, Wolters C, Nicol T, Blondis TA. "Hearing loss in children with Down syndrome." J Pediatr. 1993 Jul;123(1):S9-12. PMID 8320600] Frequent infections of the middle ear( otitis media) and obstructive sleep apneaare also more common DS. [Clarke RW. "Ear, nose and throat problems in children with Down syndrome." Br J Hosp Med (Lond). 2005 Sep;66(9):504-6. Review. PMID 16200785] Instability of the atlanto-axial jointoccurs in ~15% of people with DS and may lead to the neurologic symptoms of spinal cord compression. [Pueschel SM, Scola FH. "Atlantoaxial instability in individuals with Down syndrome: epidemiologic, radiographic, and clinical studies." Pediatrics. 1987 Oct;80(4):555-60. PMID 2958770]
Prevention and screening
American Academy of Pediatrics, among other health organizations, has issued a series of recommendations for screening individuals with Down Syndrome for particular diseases.American Academy of Pediatrics Committee on Genetics. (2001) "Health Supervision for Children With Down Syndrome." Pediatrics 107(2):442-449. Online at [http://aappolicy.aappublications.org/cgi/content/full/pediatrics;107/2/442 Health Supervision for Children With Down Syndrome] . Accessed 13 August 2006] These guidelines enable health care providers to identify and prevent important aspects of DS. All other typical newborn, childhood, and adult screening and vaccination programs should also be performed.
Initial examination of newborns with DS should pay particular attention to certain physical signs which are more commonly found in DS. Evaluation of the
red reflexcan help identify congenital cataracts. Movement of the eyes should be observed to identify strabismus. Constipation should raise concerns for Hirschsprung's diseaseand feeding problems should prompt intense education to ensure adequate input and nutrition.
At birth, an ultrasound of the heart (
echocardiogram) should be done immediately in order to identify congenital heart disease (this should be carried out by someone with experience in peadiatric cardiology). A complete blood count should be done in order to identify pre-existing leukemia. A hearing test using brainsteam auditory evoked responses (BAERS) testing should be performed and any hearing deficits further characterized. The thyroid function should also be tested. Early Childhood Interventionshould be involved from birth to help coordinate and plan effective strategies for learning and development.
Childhood and adulthood
As children with DS grow, their progress should be plotted on a
growth chartin order to detect deviations from expected growth. Special growth charts are available so that DS children can be compared with other children with DS. Thyroid function testing should be performed at 6 months and 12 months of age as well as yearly thereafter. Evaluation of the ears for infection as well as objective hearing tests should be performed at every visit. Formal evaluation for refractive errors requiring glasses should be performed at least every two years with subjective vision assessments with each visit. After the age of three, an x-ray of the neck should be obtained to screen for atlanto-axial instability. As the child ages, yearly symptom screening for obstructive sleep apnea should be performed.
Treatment of individuals with Down Syndrome depends on the particular manifestations of the disease. For instance, individuals with congenital heart disease may need to undergo major corrective surgery soon after birth. Other individuals may have relatively minor health problems requiring no therapy.
Plastic surgeryhas sometimes been advocated and performed on children with Down syndrome, based on the assumption that surgery can reduce the facial features associated with Down syndrome, therefore decreasing social stigma, and leading to a better quality of life. [cite journal| author=Olbrisch RR| title=Plastic surgical management of children with Down syndrome: indications and results| journal=British Journal of Plastic Surgery| year=1982| volume=35| pages=195–200| doi=10.1016/0007-1226(82)90163-1] Plastic surgery on children with Down syndrome is uncommon, [cite book|author=Parens, E. (editor)|year=2006| title=Surgically Shaping Children : Technology, Ethics, and the Pursuit of Normality| publisher=Johns Hopkins University Press| location=Baltimore| id=ISBN 0-8018-8305-9] and continues to be controversial. Researchers have found that for facial reconstruction, "...although most patients reported improvements in their child's speech and appearance, independent raters could not readily discern improvement...." [cite journal| author=Klaiman, P and E Arndt| title=Facial reconstruction in Down syndrome: perceptions of the results by parents and normal adolescents| journal=Cleft Palate Journal| volume=26| year=1989| pages=186–190; discussion 190–192| pmid=2527096 Also, see cite journal| author=Arndt, EM, A Lefebvre, F Travis, and IR Munro| title=Fact and fantasy: psychosocial consequences of facial surgery in 24 Down syndrome children| journal=Br J Plast Surg| year=1986| volume=4| pages=498–504| pmid=2946342| doi=10.1016/0007-1226(86)90120-7] For partial glossectomy (tongue reduction), one researcher found that 1 out of 3 patients "achieved oral competence," with 2 out of 3 showing speech improvement. [cite journal| title=The efficacy of tongue resection in treatment of symptomatic macroglossia in the child| author=SA Pensler| journal=Ann Plast Surg| year=1990| volume=25| pages=14–17| doi=10.1097/00000637-199007000-00003See also cite journal| title=The impact of a partial glossectomy on articulation and speech intelligibility| author=KM Van Lierde, H Vermeersch, J Van Borsel, P Van Cauwenberge| year=2002/2003| journal=Oto-Rhino-Laryngologia Nova| volume=12| pages=305–310| doi=10.1159/000083122] Len Leshin, physician and author of the [http://ds-health.com ds-health website] , has stated, "Despite being in use for over twenty years, there is still not a lot of solid evidence in favor of the use of plastic surgery in children with Down syndrome." [cite web| title=Plastic Surgery in Children with Down Syndrome| author=Leshin, L| url=http://www.ds-health.com/psurg.htm| accessdate=2006-07-25| year=2000] The [http://www.ndss.org National Down Syndrome Society] has issued a "Position Statement on Cosmetic Surgery for Children with Down Syndrome" [cite web|author=National Down Syndrome Society| title=Position Statement on Cosmetic Surgery for Children with Down Syndrome| url=http://www.ndss.org/content.cfm?fuseaction=InfoRes.HlthArticle&article=34|accessdate=2006-06-02] which states that "The goal of inclusion and acceptance is mutual respect based on who we are as individuals, not how we look."
The Institutes for the Achievement of Human Potentialis a non-profit organization which treats children who have, as the IAHP terms it, "some form of brain injury," including children with Down syndrome. The approach of "Psychomotor Patterning" is not proven, [For criticism of the method, see web cite| author=Novella, S|url=http://www.quackwatch.org/01QuackeryRelatedTopics/patterning.html| title=Psychomotor Patterning|accessdate=2006-06-02] and is considered alternative medicine.
While there is evidence pointing to a shortened life expectancy for people with Down syndrome, it is clear that persons with Down syndrome are living longer then they have previously. One study, carried out in the United States, showed an average lifespan of 49 years.cite news |first = Emma
last = Young
title = Down's syndrome lifespan doubles
url = http://www.newscientist.com/article.ns?id=dn2073
work = New Scientist
date = 2002-03-22
accessdate = 2006-10-14
language = ] , as opposed to 25 years of age before 1980, and approximately 10 years of age in 1929.In the past congenital heart disease, leukemias,untreated hypothyroidism and infections contributed to mortality, where today the causes of death are more likely to be complications of Alzheimer's disease.It remains to be seen what their ultimate life expectancy will be,but it seems unlikely to approach the national average, mainly because of the burden of the neurodegenerative disorders to which they are predisposed.
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