Down Syndrome

Chapter 28 Down Syndrome



Kathryn Rausch Crowell, MD




Speaking Intelligently


General pediatricians provide care for infants and children with Down syndrome in many different capacities. They may provide prenatal counseling to couples who have received a prenatal diagnosis. The pediatrician may evaluate a newborn who was not diagnosed prenatally but whose appearance and examination are suspicious for Down syndrome in the nursery.1 In addition to evaluation and care of the baby, it is important to be prepared for the difficult conversation with the parents. Pediatricians also provide ongoing primary care for children with Down syndrome, which will include routine primary care, care needed for specific associated diagnoses, and screening specific to Down syndrome, such as periodic testing for hypothyroidism and monitoring for middle ear effusion.1



Medical Knowledge and Patient Care



Background and Definitions


Trisomy 21, or Down syndrome, is a genetic disorder that includes a combination of birth defects. Down syndrome is associated with intellectual disability (formerly known as mental retardation), characteristic facial features, congenital heart defects, visual and hearing impairments, gastrointestinal problems, cryptorchidism, and other health problems, including hypothyroidism. The phenotype is variable, and the severity of these problems is highly variable among affected infants. Down syndrome is one of the most common genetic birth defects, affecting approximately 1 in 800 to 1000 babies.


In Down syndrome there is an extra copy of chromosome 21. Ninety-five percent of cases result from nonfamilial trisomy 21. Three to four percent of cases result from an unbalanced translocation between chromosome 21 and another chromosome, usually 14. Finally, 1% to 2% of cases result from mosaicism. In these individuals, two cell lines are present, one normal and one trisomy 21. See Nelson Essentials 49.



Clinical Features


Affected infants may be initially identified by recognizable phenotypic features. Although the phenotype is variable, there is enough consistency to allow an experienced clinician to suspect the diagnosis. The head might appear brachycephalic or microcephalic, and there may be small ears and excessive nuchal skin (i.e., at the nape of the neck). Ophthalmologic examination may reveal epicanthal folds, upward slanting palpebral fissures, and Brushfield spots. The hands typically have a single transverse palmar crease (simian crease), a short fifth finger, and clinodactyly. In addition, examination of the feet may reveal a wide space, often with a deep fissure, between the first and second toes. On neurologic examination, mild to moderate diffuse hypotonia is typical and may contribute to feeding difficulty. See Nelson Essentials 49.


image Feeding Difficulty. Although all children with Down syndrome have some degree of mental impairment and developmental delay, this becomes more apparent after infancy. In the neonatal period, hypotonia is common and may complicate an infant’s ability to effectively orally feed, and inadequate weight gain is common. Consequently, early on, infants need to be followed closely to evaluate for feeding difficulties and weight loss. A speech therapist may be necessary to support feeding techniques. After hospital discharge, all infants with Down syndrome should be referred to early intervention for evaluation by speech, occupational, and physical therapists. Although most children with Down syndrome have delayed acquisition of both fine and gross motor skills, early intervention techniques, education, and vocational training have all been shown to improve the developmental quotient of children with Down syndrome. In later childhood, these children have a tendency to gain excessive weight and are at risk for obesity. They tend to have short stature, and there are specific Down syndrome growth charts to provide height and weight and head circumference data relative to a population of children with Down syndrome.
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Jul 18, 2016 | Posted by in PEDIATRICS | Comments Off on Down Syndrome

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