FG syndrome

FG syndrome (FGS; also known as Opitz-Kaveggia syndrome) is a rare genetic syndrome linked to the X chromosome and causing physical anomalies and developmental delays. First reported by Opitz and Kaveggia in 1974, its major clinical features include retardation, hyperactivity, hypotonia (low muscle tone), and a characteristic facial appearance including macrocephaly (an abnormally large head).

Characteristics
FG syndrome's major clinical features include mental retardation, usually severe; hyperactive behavior, often with an outgoing personality; severe constipation, with or without structural anomalies in the anus such as imperforate anus; macrocephaly; severe hypotonia; a characteristic facial appearance due to hypotonia, giving a droopy, "open-mouthed" expression, a thin upper lip, a full or pouting lower lip, and partial or complete loss of the corpus callosum. About a third of reported cases of individuals with FG syndrome die in infancy, usually due to respiratory infection; premature death is rare after infancy.

Genetics
Types include:

History


The name of the syndrome comes from the initials of the surnames of two sisters, who had five sons with the syndrome. The first study of the syndrome, published in 1974, established that it was linked to inheritance of the X chromosome.

A 2008 study concluded that Kim Peek, who was the basis for the Dustin Hoffman character in the movie Rain Man, probably had FG syndrome.