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Down Syndrome

Down Syndrome. Objectives. Be familiar with the genetic basis for Down Syndrome Know the common physical stigmata of Down Syndrome Be comfortable caring for children with Down Syndrome and what testing and routine care is recommended. Etiology.

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Down Syndrome

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  1. Down Syndrome

  2. Objectives • Be familiar with the genetic basis for Down Syndrome • Know the common physical stigmata of Down Syndrome • Be comfortable caring for children with Down Syndrome and what testing and routine care is recommended

  3. Etiology • Most commonly recognized genetic cause of mental retardation: prevalence of 9.2 cases per 10,000 live births • Diagnosed by Karyotype: • 95% - Trisomy 21 • 2% - Mosaicism (mix of diploid and trisomy 21) • 3 % - Robertsonian translocation (part or all of extra chromosome 21 fused with another chromosome)

  4. Etiology • 95 percent of occurrences of trisomy 21 result from nondisjunction during meiotic division of the primary oocyte • Most trisomy 21 pregnancies prove to be nonviable • 1/4 of fetuses with trisomy 21 survive to term

  5. Etiology – Risk Assessment • Maternal Age • 1/1,300 for a 25-year-old woman • 1/365 for age 35 • 1/30 for age 45 • At age 35, the second-trimester prevalence of trisomy 21 (1/270) approaches the estimated risk of fetal loss due to amniocentesis (1/200) – This became cutoff for screening

  6. Advanced Maternal Age as Risk Factor

  7. Etiology – Risk Assessment • 15-18 Weeks Gestation : triple test detects 60% of pregnancies affected by trisomy 21 • False positive rate about 5% • Alpha-fetoprotein (AFP), unconjugated estriol and human chorionic gonadotropin (hCG) • Ultrasound in 1st trimester – increases sensitivity to close to 80% with no change in false positive rate

  8. Etiology – Risk Assessment • Ultrasound in 2nd trimester findings possible: • Intrauterine growth restrictionMild cerebral ventriculomegalyChoroid plexus cystsIncreased nuchal fold thicknessCystic hygromasEchogenic intracardiac fociCongenital heart defectsIncreased intestinal echogenicityDuodenal atresia ("double-bubble sign")Renal pelvis dilationShortened humerus and femurIncreased iliac wing angleIncurving (clinodactyly) and hypoplasia of the fifth fingerIncreased space between first and second toesTwo-vessel umbilical cord

  9. Etiology – Risk Assessment

  10. Brachycephaly 63-98% Oblique palpebral fissures 70-98% 1st & 2nd toe gap 44-97% Loose skin on neck 17-94% Hyperflexibility 47- 92% Ear abnormalities (low folded, stenotic) 28-91% Protruding tongue and small, narrow palate 32-89% Flat nasal bridge 57-87% Muscular hypotonia 21-85% Epicanthal folds 28-79% Brushfield spots (ring of iris speckles) 35-78% Short fifth finger 51-77% In-curved fifth finger 43-77% Short broad hands 38-75% High arched palate 59-74% Single palmar crease 42-64% Cardiac defect (1/2 AV canal defects) 40-50% Transient myelodysplasia of the newborn 10% Duodenal atresia 5-8% Yellow - Highly specific to Down Syndrome Clinical Findings

  11. Medical Problems By System

  12. Cardiac • ALL newborns with the syndrome should have an electrocardiogram and a screening echocardiogram, even if a murmur is not present. • Most common anomalies are: • complete atrioventricular canal defects (60 percent) • ventricular septal defects (32 percent) • tetralogy of Fallot (6 percent) • ostium secundum atrial septal defect (1 percent) • The long-term prognosis is best when an infant with a cardiac defect is promptly referred to a pediatric cardiologist for medical management to prevent pulmonary hypertension or to a pediatric cardiac surgeon for early surgical repair

  13. Gastrointestinal • Various defects are associated with Down syndrome: Esophageal atresia, Tracheoesophageal fistula, Pyloric stenosis, Duodenal atresia, Meckel's diverticulum, Hirschsprung's disease, Imperforate anus • GERD– may require medication • Constipation – usually dietary management is enough

  14. Ear, Nose and Throat Problems • Midfacial malformations prevent optimal drainage of eustachian tubes and sinuses • susceptible to otitis media, sinusitis and pharyngitis • sequelae can include hearing loss, chronic infection, pneumonia, sepsis, endocarditis or congestive heart failure in infants with concomitant heart defects • Auditory brainstem response testing to evaluate for hearing loss should be performed when an infant with Down syndrome by 6 months old

  15. Orthopedic Problems • Associated problems: Atlanto-occipital instability, Atlantoaxial instability, Hyperflexibility, Scoliosis, Late hip dislocation (after two years of age), Slipped capital femoral epiphysis, Patellar subluxation or dislocation, Foot deformities • Xrays of the flexed and extended cervical spine were recommended as screening tests in the past for atlantoaxial instability when children with Down syndrome reach the age of two years or before they undergo general anesthesia • Although screening radiographs are controversial, 13% of children with Down syndrome have asymptomatic atlantoaxial instability that should be monitored and that precludes their participation in contact sports • ALL children with Down Syndrome should be referred to Early Intervention from birth for physical therapy services

  16. Endocrine Disorders • Thyroid Disease – thyroid function tests should be done at birth and at least annually • Gonadal dysfunction and growth hormone deficiency - These problems may require hormonal therapy

  17. Ophthalmology • Congenital cataracts - occurs more frequently in children with Down syndrome than in other children • Red (fundus) reflexes should be checked at birth. • Consultation with a pediatric ophthalmologist during the first year is necessary • Ocular problems that may be correctable: Congenital and acquired cataracts, Nystagmus, Strabismus, Dacryostenosis, Blepharitis, Keratoconus, Refractive errors (myopia, astigmatism), Amblyopia, Increased retinal vasculature, Glaucoma

  18. Other Systems • Transient myeloproliferative disorder (leukemoid reaction) occurs in 10% • Learning point: normal infants who exhibit leukemoid reactions within the 1st two months of life should be evaluated by karyotype for mosaic Down syndrome • Seizures - 5-10% of Down Syndrome children • Dental: Delayed eruption, Atypical patterns of eruption, Congenitally missing teeth, Unusually shaped teeth, Enamel defects, Orthodontic problems, Bruxism, Periodontal disease

  19. Psychosocial Issues • Initial Counseling: • If not sure of the diagnosis when initial testing done, say so. “We are concerned that your child shows some signs of Down Syndrome and with your permission I would like to draw blood and test for this.” You should point out what physical traits you see to help with denial by the parents. • Try to have both parents present when you talk to them - The parents may react with shock, denial, anger, grief, fear, acceptance or any combination of these emotions. The physician should acknowledge the parents' feelings and their right to have them • The infant should be referred to by name, so that his or her worth as a human being can be stressed.

  20. Psychosocial Issues • The mother and father may benefit from an opportunity to meet with the parents of an older child with Down syndrome. Such a meeting may provide tangible proof that a child with Down syndrome can thrive and become a vital part of the family • Provide web based and written resources

  21. Final Note • Life tables published in 1989 showed that more than 50 percent of infants with Down syndrome could be expected to live more than 50 years • As mortality rates for the operative repair of congenital heart defects continue to decrease, survival may increase considerably

  22. Resources • Books • Libby Kumin. Communication skills in children with Down syndrome: a guide for parents. Rockville, Md.: Woodbine House, 1994. • Siegfried M. Pueschel. A parent's guide to Down syndrome: toward a brighter future. Baltimore: Paul H. Brookes, 1990. • Kay Stray-Gundersen, ed. Babies with Down syndrome: a new parents' guide. 2d ed. Bethesda, Md.: Woodbine House, 1995. • World Wide Web • America Online • --Personal Empowerment Network chatroom (keyword: PEN) • --Better Health and Medical Network, disabilities forum, support chats, Down syndrome • Down Syndrome newsgroup: http://www.downsyndrome.com (other resources linked to this Web page)   • Organizations • National Down Syndrome Congress: 1-800-232-6372 • National Down Syndrome Society: 1-800-221-4602 • National Parent to Parent Support and Information System: 1-800-651-1151 • La Leche League International (breast-feeding information and support): 1-800-525-3243

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