Trisomy 21 is caused, as the name suggests, by the triplication of the 21st chromosome. Genes which, simplified, contain the blueprints for our cellular structure, are grouped along rod-like structures called chromosomes. Normally, the nucleus of each cell contains 23 pairs of chromosomes, half of which are inherited from each parent. In Down syndrome (DS), however, the cells usually contain not 46, but 47 chromosomes. This excess genetic material, in the form of additional genes along the 21st chromosome, results in DS. The estimated incidence of Down syndrome is between 1 in 1,000 to 1 in 1,100 live births. Each year approximately 3,000 to 5,000 children are born with this chromosome disorder. It is believed there are about 250,000 families in the United States who are affected by DS. (Berg, 614) Discussed in this paper will be a more detailed description of the pathophysiology of Down syndrome, as well as the discovery, possible causes, physical features, associated conditions, possible treatment, electroneurodiagnostic corollaries, and psychosocial issues. Down syndrome or Trisomy 21 has been alluded to in art, literature and science for centuries. One of the more interesting of these is the "Changeling" in Gaelic myth. It was believed that when a child was born with the dysmorphic characteristics now associated with DS i.e. epicanthal folds, simian creases, small ears etc., an elf or evil spirit had replaced the infant that was meant to be theirs with the offspring of a mischievous creature. However, it wasn't until 1866, that a physician named John Langdon Down published an essay in England in which he described a set of children with common features who were distinct from other children with mental retardation. Down was superintendent of an asylum for children with mental retardation in Surrey, England when he made the first distinction between children who were cretins (later to be found to have hypothyroidism) and what he ref...
