A triple threat: Down syndrome, congenital central hypoventilation syndrome, and hirschsprung disease

Down syndrome (DS) is recognized by characteristic facial features, intellectual disability, and an increased risk for cardiac malformations and duodenal atresia. Recently, Hirschsprung disease (HSCR), or congenital aganglionic megacolon, has been seen more often among patients with DS. Given the systemic nature of DS-related features, it is natural to attribute neonatal complications to the chromosomal aberration. We describe a biracial male infant with DS who had significantly delayed defecation and required continuous ventilator support, but had no primary cardiac or lung disease. Subsequent evaluations confirmed total colonic aganglionosis. Because we were unable to safely extubate the infant, a diagnosis of congenital central hypoventilation syndrome (CCHS) was considered and confirmed by molecular analysis of the PHOX2B gene, revealing a heterozygous polyalanine repeat-expansion mutation containing 27 repeats (normal gene contains 20 repeats). HSCR coexisting with CCHS is known as Haddad syndrome. This is the first reported case with co-occurrence of DS, CCHS, and HSCR.