Rieger syndrome is a rare disorder characterized by absence and/or malformation of certain teeth, mild craniofacial (relating to the head and the face) abnormalities, and various eye abnormalities. The eye abnormalities, referred to as Rieger eye malformations, may be present separately or as a part of Rieger syndrome.
First characterized by Herwigh Rieger, an Austrian ophthalmologist in 1935, Rieger syndrome is a dominantly inherited disease. Disease expression is highly variable, including craniofacial, ocular, and dental malformations. Symptoms may also include myotonic dystrophy (a condition characterized by delay in the ability to relax muscles), umbilical abnormalities (abnormalities relating to where the umbilical cord attaches to a baby), and other defects. Psychomotor retardation, a slowing of the motor action directly proceeding from mental activity, occurs in some cases.
Rieger syndrome is also sometimes referred to as goniodysgenesis hypodontia, iridogoniodysgenesis with somatic anomalies, or RGS. It is a multiple congenital anomaly syndrome, a syndrome marked by multiple abnormalities at birth. Currently, there are two genetic types of Rieger syndrome identified. Type I results from a mutation on chromosome 4 and Type II on chromosome 13.
Rieger syndrome is inherited as an autosomal dominant disease. In autosomal dominant inheritance, a single abnormal gene on one of the autosomal chromosomes (one of the first 22 non-sex chromosomes) from either parent can cause the disease. One of the parents will have the disease (since it is dominant) and is the carrier. Only one parent needs to be a carrier in order for the child to inherit the disease. A child who has one parent with the disease has a 50% chance of also having the disease.
There is evidence that there is more than one genetic form of Rieger syndrome. The disease gene responsible for Rieger syndrome Type I is caused by mutations in the RIEG1 gene, which is located on the long arm (q) of chromosome 4 (4q25-Q26).
Linkage studies have indicated that a second type of Rieger syndrome, Type II, maps to the long arm of chromosome 13, at 13q14 (gene RIEG2).
Jennifer F. Wilson MS, The Gale Group Inc., Gale, Detroit,