A 2-day-old baby boy is brought to the emergency department for vomiting. The patient’s mother is a 25 year-old single parent who did not receive prenatal care, and the baby was born at home via vaginal delivery at 39 weeks gestation. The mother reports that the baby vomits whenever she tries to breastfeed him and that the emesis appears green and thick. The infant is noted to have epicanthal folds, upward-slanting palpebral fissures, flat nasal bridge, a single transverse palmar (simian) crease, and small ears (Figures 221-1 and 221-2). The examining physician suspects the child has Down syndrome and orders an abdominal x-ray, which reveals a “double-bubble,” consistent with duodenal atresia, and is associated with Down syndrome. (Figure 221-3). The baby undergoes surgical correction of the atresia and recovers completely. A chromosomal analysis confirms the diagnosis of Down syndrome.
Epicanthal folds, upslanting palpebral fissures, flat nasal bridge, and wide gap between the first and second toe in an infant with Down syndrome. (Used with permission from Cleveland Clinic Children’s Hospital Photo Files.)
Single transverse palmar crease in an infant with Down syndrome (simian crease). This is seen in about 50 percent of infants with Down syndrome and can be seen in infants and children who do not have Down syndrome. (Used with permission from Cleveland Clinic Children’s Hospital Photo Files.)
“Double bubble” sign of duodenal atresia on plain x-ray in a child with Down syndrome. Infants with Down syndrome have an increased incidence of intestinal atresias. (Used with permission from Elumalai Appachi, MD.)
Down syndrome (DS) is an aneuploidy that develops from excess genetic material on chromosome 21, and results in a distinctive phenotypic appearance.1,2 Children commonly present with congenital cardiac, hematologic, musculoskeletal, visual, and/or auditory defects.3 The incidence of DS increases with maternal age.4
DS is the most commonly occurring genetic disorder among live births, occurring in 1 in 691 of all live births in the US.5
The risk of having a prenatal diagnosis for DS is thought to be higher since it is estimated that 67 percent women (range 61% to 93%) in the US with a fetus demonstrating trisomy 21 will terminate the pregnancy.6
Compared to Caucasian mothers, the prevalence ratio of trisomy 21 live births was 0.77 among African American mothers and 1.12 among Hispanic mothers. These differences could reflect ethnic differences in accessibility to prenatal screening, variation in the decision to terminate the pregnancy, ...