Chapter 21 Down Syndrome
PATHOPHYSIOLOGY
Down syndrome, the most common chromosomal condition that results in intellectual disabilities, is associated with an extra chromosome on chromosome 21. Current genetic studies have found that this chromosome consists of 329 genes. Understanding how these genes work will provide a real opportunity to understand how this condition occurs and how the characteristics of this condition result.
Down syndrome may occur by one of three mechanisms: a free trisomy or nondisjunction (about 95% of cases), translocation (about 3% to 5%), or mosaicism (about 1% to 2%). Free trisomy or nondisjunction occurs when three copies of chromosome 21 result in 100% of the cells. This situation arises from an unequal distribution of chromosomes in anaphase 1 or 2 during meiosis or in the anaphase of mitosis. The phenotype for nondisjunction and translocation is the same.
Nondisjunction occurs by maternal meiotic origin in approximately 90% of cases; it results in three copies of chromosome 21. Nondisjunction usually occurs spontaneously and is not familial. Approximately 8% of cases are caused by paternal factors, most often advanced paternal age, of 55 years or older. Factors that can influence the occurrence of nondisjunction Down syndrome are maternal age, earlier menopause, and gene polymorphisms that influence folate metabolism.
Translocation happens when all or part of a chromosome is exchanged with another chromosome. This can result in a balanced or unbalanced translocation, depending upon the amount of chromosomal material involved. In Down syndrome, translocations are unbalanced; the most common combination of chromosomes involved is 14 and 21 (14;21), followed by both copies of the chromosome 21 (21;21). In 75% of all cases of unbalanced translocations, the cause is not familial, but it is in 25% of the cases. The cause is considered to be multifactorial and independent of parental age.
Mosaicism is characterized by the absence of trisomy (three copies) of chromosome 21 in 100% of the cell lines. This form of Down syndrome is most frequently caused by maternal meiotic nondisjunction. Individuals with mosaic Down syndrome have fewer phenotypic features. Diagnosis of the genotype of Down syndrome is made through a chromosome analysis (American Academy of Pediatrics Committee on Genetics, 2001; Lashley, 2005).
There are many physical features of Down syndrome, also called the phenotype, that do not exist in every child who has the condition. Presence or absence of a physical feature usually does not indicate severity of the condition. The exception is the degree of mental retardation, which would affect developmental outcomes. For information on the complications and secondary problems associated with Down syndrome, refer to Complications in this chapter.
INCIDENCE
1. The incidence of Down syndrome is approximately 1 in 800 live births, and the prevalence is generally accepted to be 1 in 650 to 1000 live births.
2. The availability of prenatal diagnosis, especially in women of advanced maternal age, has influenced these figures.
3. The incidence of having a child with Down syndrome for a woman in her twenties is approximately 1 in 2000 live births. This figure increases to approximately 34 in every 1000 live births for the woman who is age 45.
4. Down syndrome may occur three ways: nondisjunction, translocation, or mosaicism.
5. Down syndrome is found in all ethnic groups and races. Incidences are higher in Hispanic and African American mothers who are age 35 years and older.
6. The risk of recurrence varies by the type of transmission.
CLINICAL MANIFESTATIONS
1. Down syndrome is diagnosed at birth because of distinctive phenotype, but confirmed by karyotype (see more under Laboratory and Diagnostic Tests in this chapter).
2. Visual diagnosis may be more difficult in newborns of color since the phenotypic characteristics may not be obvious and other signs such as Mongolian spots, common in African Americans, may not be identified as part of a syndrome.
3. There are more than 50 characteristic features of Down syndrome occurring on the skull, the eyes, the ears, the nose, the mouth, the neck, the chest, the abdomen, and the extremities, and affecting physical growth and development in all domains. No one feature is diagnostic, and not every characteristic feature is present in any one person with Down syndrome.
4. The most common features are generalized hypotonia, mental retardation, incurved fifth finger, simian crease, flattened occipital, small nose with flat nasal bridge, epicanthic folds, Brushfield’s spots, absent Moro reflex, wide spaces between the first and second toes, hearing impairment, ocular problems, thyroid problems, dental problems, and/or orthodontic problems.
COMPLICATIONS
1. Premature aging is present and affects development throughout life; early-onset Alzheimer’s disease may be a factor.
2. Congenital anomalies that occur with greater frequency in Down syndrome include congenital cardiac disease (endocardial cushion defects and septal defects most common), gastrointestinal malformations (duodenal or esophageal atresia and congenital megacolon most common), celiac disease, and leukemia (transient myeloproliferative disorder, in particular).
3. Mental health problems: behavioral problems, depression, and/or attention deficit hyperactivity disorder (ADHD) can also occur in children with Down syndrome (Crocker, 2006; Lashley, 2005; Nehring, 2004).
LABORATORY AND DIAGNOSTIC TESTS
1. The best practice to obtain an accurate diagnosis is to offer pregnancy screening by blood test for chromosomal anomalies and neural tube defects, followed by cytogenic diagnosis. This combination serum test, often called a quadruple screen, includes alpha fetoprotein, human chorionic gonadotropin, unconjugated estriol, and dimeric inhibin-A in maternal serum. This blood test is done during weeks 16 to 18 of pregnancy. Researchers are currently examining the use of the quadruple screen with a fetal ultrasound for nuchal translucency during gestational week 11 and adding the quadruple screen during the second trimester for confirmation, as a more efficacious screening protocol.
2. Invasive screening tests include chorionic villi sampling during gestational week 12 and amniocentesis during week 16.
3. Diagnosis of Down syndrome is made through chromosome analysis.
4. Ocular defects are common; the child with Down syndrome should see an ophthalmologist by 6 months of age and then, beginning around age 3 years, every 2 years. Vision should be checked yearly.
5. Auditory defects are also common. Auditory brainstem response testing should be completed by 3 months of age, followed by evaluation by a specialist every 6 months up through age 3 years and annually thereafter.
6. Otoscopy and tympanometry should be done at each visit by the specialist.
7. Periodontal disease is common, so the child with Down syndrome should see a dentist every 6 months beginning at age 18 months.
8. A full cardiac evaluation should be completed in infancy, with follow-up as needed according to occurrence of cardiac conditions.
9. Thyroid-stimulating hormone levels should be measured at 6 and 12 months and annually thereafter, since thyroid dysfunction is a common condition.
10. Children with Down syndrome should first be checked for atlantoaxial instability between 3 and 5 years and then as needed before athletic involvement.
11. The risk for hip dislocation is present, so the child should be checked for this condition during well-child visits through 10 years of age and if a gait abnormality is present.
12. Because of the risk of mitral value prolapse, this condition should be checked for, beginning in adolescence.
13. IgA-antiendomysium antibodies of immunoglobulin A class should be assessed when the child is between 2 and 3 years old because of the higher prevalence of celiac disease.
MEDICAL MANAGEMENT
At present, it is not possible to reverse Down syndrome and cure this condition through treatment(s) of the genetic cause. Medical advancements, genetic discoveries, and interdisciplinary best practices in recent years have directed current standards of practice, which include genetic counseling, treatment and/or surgical correction of congenital anomalies and sensory defects, prevention and/or maintenance of secondary conditions, participation in early intervention programs, and inclusion in school settings from ages 3 through 21 years. An interdisciplinary approach, based on best practices, is recommended to (a) treat or correct congenital anomalies and sensory defects; (b) prevent periodontal disease and obesity; (c) prevent or maintain secondary conditions such as arthritis, atlantoaxial instability, behavior problems, celiac disease, constipation, dermatologic problems, diabetes, feeding problems, leukemia, obstructive sleep apnea, seizures, sensory defects, thyroid dysfunction, and/or upper respiratory infections; and (d) provide sex education and assess for contraception needs in adolescence. Alternative therapies such as use of piracetam, nutritional supplements, human growth hormone therapy, and antioxidants should not be prescribed, since current research evidence has not found these therapies to be beneficial or efficacious (American Academy of Pediatrics Committee on Genetics, 2001; Cohen, 1999).
NURSING ASSESSMENT
1. Assess for feeding problems.
2. Assess for sleep disorders.
3. Assess growth and development, and refer as needed to other disciplines.
4. Assess child’s ability to perform age-appropriate self-care skills.
5. Assess child’s ability to get along with others, make friends, and participate in social activities.
6. Assess child’s and adolescent’s school experiences.
7. Assess child’s and adolescent’s exercise habits.
8. Assess presence of “self-talk” in older child and adolescent.
9. Assess knowledge of condition and its effect on child’s and adolescent’s life.
10. Assess sexual knowledge and need for contraception during adolescence.
11. Assess for behavioral problems, ADHD, and/or depression (especially in adolescence).
12. Assess for health-related self-care skills, vocational skills, and ability to live independently during adolescence in preparation for transition to adulthood.
13. Assess for need for guardianship once the age of majority is reached during adolescence.
14. Assess parental response to birth of infant with Down syndrome. Throughout childhood and adolescence, assess meaning of child to parents and impact on their life.
15. Assess whether parents’ expectations for their child are developmentally age-appropriate.
16. Assess parents’ understanding of the condition throughout their child’s life.
17. Assess the impact of the child with Down syndrome on siblings and other family members.
18. Assess cultural and religious influences on family responses and impact of having a family member with Down syndrome.
19. The nurse should assess his or her own feelings and attitudes toward caring for a child with an intellectual disability and providing education, support, and advocacy to family members.
NURSING DIAGNOSES
• Caregiver role strain, Risk for
• Communication, Impaired verbal
• Growth and development, Delayed
• Nutrition, more than body requirements, Risk for imbalanced
• Self-care deficit, Bathing/Hygiene
• Self-care deficit, Dressing/Grooming
• Self-care deficit, Toileting
• Self-esteem, Risk for situational low
• Skin integrity, Risk for impaired
NURSING INTERVENTIONS
Infancy, Toddler, Preschool
1. Assist mothers if breastfeeding, or parents if bottle feeding, if hypotonia affects sucking ability. Different strategies may be suggested, such as more frequent and shorter feedings. Blended or chopped foods may be needed when solid foods are introduced. If aspiration or serious problems occur, an occupational therapist should be consulted or a referral made.
2. Assist the parents and siblings in making a realistic appraisal of what the infant with Down syndrome should be expected to do and when. Together, across time, identify the child’s strengths and limitations.
3. Identify formal and informal supports available to the parents, and suggest that they visit with a member of a local Down syndrome support group.
4. Monitor growth and development using Down syndrome growth charts.
5. Refer parents to area early intervention programs.
6. Serve as child and parent advocate in individualized family service plan (IFSP) meetings (refer to Appendix G).
7. Inform parents about federal and state laws affecting children with intellectual disabilities.
8. Provide anticipatory guidance to the parents for typical infant milestones, and provide information on average ages for infants with Down syndrome based on research literature.
9. Use a life-span approach to providing anticipatory guidance on child’s developmental milestones.
10. Advise parents that toilet training will be delayed; the median age is 3 years. Normal methods of training may be used.
11. Encourage parents to use discipline methods that are developmentally appropriate. Parents should not be overly protective or allow their child to be manipulative because of having Down syndrome.
12. Assist parents in finding a medical “home” if their current pediatrician has not had experience in caring for a child with Down syndrome.
13. Monitor for constipation. Use age-appropriate treatment methods.
14. Teach parents about common secondary conditions for infants. In infancy, this includes eye, ear, heart, intestinal, and upper respiratory conditions. Discuss additional screening and testing that will be done for the infant and child with Down syndrome to check for these conditions.
15. Refer for sleep study, if symptoms of sleep apnea appear.
16. Discuss alternative and complementary treatments with parents, and provide up-to-date information on the value of each type of method. There is no cure for Down syndrome, and parents must sometimes be assisted to understand why something may or may not work. This discussion could also include the use of plastic surgery to make the child “appear more normal.”
17. Provide up-to-date information and relevant references including Internet sites as needed.
Childhood
1. Monitor impact of parenting and living with a child with Down syndrome on each parent and sibling.
2. Assist family as needed in finding insurance, dental care, and other, related services.
3. Ask parents if they have any questions about appropriate developmental milestones, behavior, or health concerns. Follow through as needed with further assessment or referral.
4. Monitor growth and development. In particular, screen the child’s expressive and receptive language skills. Refer to speech therapist if necessary.
5. Encourage parents to enroll child in inclusive child care setting, preferably one that has had previous experience with a child with Down syndrome.
6. Refer to inclusive preschool for 3- to 5-year-olds, and assist parents, if necessary, to interview school officials and teachers to make sure child’s academic needs are met. Serve as an advocate for the child and parents in individualized education plan (IEP) and individualized health plan (IHP) meetings.
7. Assist parents with choosing an appropriate school system that provides for inclusive education. Nurses can assist in educating parents on federal laws concerning the education of children with intellectual disabilities.
8. Monitor child’s diet, and provide nutritional education as needed. Referral to a nutritionist may be needed, especially if celiac disease is diagnosed, necessitating a gluten-free diet.
9. Monitor presence of secondary conditions, including behavioral and mental health issues, and intervene as needed.
10. Allow child to be a partner in making decisions about needed health care. Such planning should be centered on the persons involved, not on the requirements of the health care system.
11. Assist the child and parents to identify community programs, such as Boy and Girl Scouts, 4-H, YMCA, Special Olympics, music-related programs, based upon their individual needs, interests, and preferences.
Adolescence
1. Ascertain parents’ goals and plans for adolescent and his or her transition to adulthood.
2. Identify differences between adolescent’s and parents’ goals and plans, and discuss with all. Make appropriate plans for transition, including participating in the development and implementation of the adolescent’s individualized transition plan (ITP), and collaborate as needed with other professionals.
3. Discuss school experiences, especially during junior high or middle school, since this time period appears to be the most difficult for this age group. Teasing is a frequent complaint among persons in this age group who have disabilities.
4. Monitor presence of any secondary conditions and adherence with treatment. Adolescents should be as responsible as possible with their own health. Reinforcement of proper techniques or education should be provided as needed.
5. Be aware of diagnostic overshadowing, which occurs when a health professional attributes health-related signs and symptoms to Down syndrome and not to the underlying cause. An example is a complaint of “feeling down and sad,” or depressed, being attributed to having Down syndrome, as opposed to the professional probing and finding out that the adolescent just broke up with a boyfriend.
6. Provide any needed sexual education and information about contraception. Discuss risks of having a child with Down syndrome, should the female adolescent with Down syndrome become pregnant. May refer adolescent to program that discusses these topics.
7. Discuss with adolescent and parents that “self-talk” (talking to self out loud) is often present in adolescents with Down syndrome, and teach when this behavior is appropriate.
8. Assist adolescent to become own health self-advocate.
9. Plan for transition to adult medical care that includes selection of adult medical providers.
10. Monitor adolescent’s diet. Discuss proper nutrition. Watch for signs and symptoms of overweight and obesity.
11. Identify regular inclusive social interactions such as sports and social clubs.
12. Identify area self-advocacy groups, and assist adolescent to determine whether to participate in such groups.
13. Identify adolescent’s goals and plans for the future, including school, work, residential settings, and lifelong care.
Discharge Planning and Home Care
1. Make appropriate referrals to professionals and agencies for specific health-related and service-related needs.
2. Family members should be referred to appropriate community agencies for insurance, recreation, respite, counseling, and/or supportive services.
3. Facilitate transition into different settings throughout childhood, such as early intervention, preschool, school, recreational, and health care agencies.
4. Facilitate parents’ understanding of developmental milestones and realistic expectations for a child with Down syndrome. In turn, assist child and adolescent with Down syndrome to set their own realistic goals and meet them.
5. Facilitate parents’ ability to become advocates for their child and the adolescent’s ability to become a self-advocate in relation to health and all other facets of life.
6. Provide coordination of services and communication between services, as needed, to serve as a resource to parents for “the total picture.”
CLIENT OUTCOMES
1. Child or adolescent will grow up in a supportive and educated environment.
2. Child or adolescent with Down syndrome will have a positive impact on and meaning for all who interact with him or her, as well as a positive self-meaning.
3. Child or adolescent will experience inclusive settings throughout childhood in the least restrictive environment possible.
4. Child and adolescent will meet IEP objectives and annual goals.
5. Parents and adolescent will be adept at identifying needs and accessing needed resources.
6. Adolescent will become an educated health advocate.
7. Adolescent will graduate from high school and enter further education or obtain employment in an area of his or her interest.
8. Adolescent will have a satisfactory social life, which includes mobility and independence.
9. Plans will be identified for care of adolescent across the life span, including residential choices, insurance, primary health care providers, and finances.
10. Make sure that outcomes correspond to the nursing diagnoses and interventions listed in this chapter.
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