What is Trisomy 18?
Trisomy 18 is a genetic disorder which has its onset before birth and is usually fatal. In this disorder, chromosome 18 appears three times (trisomy) rather than the normal two times in the cells of the body. The most severe form of the disorder occurs when every cell in the body is affected. A less severe form, called the mosaic form, occurs when some cells have the normal chromosomal pair. Trisomy 18 is also called Edwards’ Syndrome and Chromosome 18. It causes severe mental retardation and major physical abnormalities. Common findings include low birth weight, malformed and low-set ears, small jaw, hand abnormalities, congenital heart disease, hernias, feeding and breathing problems, and a weak infant cry.