Iridogoniodysgenesis and Skeletal Anomalies
Patient Information
Characteristics
Background and History
The eye is separated into anterior and posterior chambers, separated by the iris or colored part of the eye. Abnormal development of the iris and its insertion into the edge of cornea is sometimes called iridogoniodysgenesis and is frequently associated with glaucoma, usually in infancy or childhood. This disorder involves the anterior chamber. Such malformations may be part of a syndrome complex as in this disorder when there are skeletal changes.
Clinical Correlations
The eye often appears large (in particular the cornea may be enlarged) which may be secondary to the increase in pressure as part of glaucoma. The iris appears thin and has a concave surface and this thinning may result in the pupil being displaced from its normal position (corectopia). The glaucoma is difficult to control either medically or surgically and blindness may result.
Other malformations, particularly of the skeletal system, are present. The forehead appears broad, the nose is large as are the ears, the neck is short and the great toe is short. The chest is abnormally wide. The vertebrae may be malformed while the long bones of the arms and legs are thin and wide at the ends.
Genetics
Inheritance
Only two families with this complex of findings have been reported. Because each had three affected children (of both sexes) and no other relatives had any signs of similar problems, it is likely that two copies of a mutated gene are responsible which suggests that this is an autosomal recessive condition. However, no gene mutation has been identified. In such families, it is likely that one out of three future children will have this disorder.
Pedigree
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
Diagnosis and Prognosis
The major health risk is glaucoma which requires vigorous treatment. Even then, the end result is blindness in some individuals. The skeletal malformations usually do not need treatment.
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