Smith-Lemli-Opitz Syndrome: A rare inherited disorder of lipid metabolism consisting of a deficiency of
the 7-dehydrocholesterol reductase. In type II, the severe form, infants may not
survive the newborn period. A less severe clinical expression (type I) may
include a small, abnormally long and narrow head, eye abnormalities, a broad
nasal tip with anteverted nostrils, broad lateral ridges in the roof of the
mouth, and microglossia. Other features include simian creases, syndactyly,
unusual fingertip skin patterns, and genital abnormalities. The incidence
occurs in relatively high frequency: approximately 1 in 20,000 to 30,000
births in populations of northern and central European background.