is the second most common trisomy after Down Syndrome, and
occurs in 1 / 4 ~ 8000 live births. It is three times as
prevalent in newborn girls as in boys. Trisomy 18
is characterized by microcephaly, a high forehead,
profound psycho-motor retardation, and serious heart
malformations including ventral and atrial septal defects,
and patent ductus
arteriosus, a persistent opening between the
heart chambers that prevents efficient blood flow.
Life expectancy is typically very short: 90% of children
die in the first year. Katrina (upper left) lived only a
few months. In contrast, Joseph (middle & right) lived
to two months short of 22 years.
His parents write: "It is important for readers to
understand that some, albeit very few, children with
trisomy 18 survive into adulthood. The live birth
prevalence towards girls becomes more pronounced with
age as girls dramatically out-survive boys in later
months / years."