Glaucoma, Congenital Primary B
Patient Information
Characteristics
Background and History
It has been known for a long time that too much pressure in the eye can cause blindness. This is most commonly diagnosed in adults but less than 3 percent of individuals with glaucoma have this early onset variety.
Clinical Correlations
Early onset glaucoma, sometimes called congenital or juvenile, can occur as an isolated condition or as part of a large number of syndromes. The pressure in the eye may be too high even before birth or may become apparent at any time in the first two decades. Typically, the elevated pressure is found neonatally or the first year of life when it is associated with general irritability, light sensitivity, excessive tearing, and evidence of decreased vision. The eye may appear abnormally large and the cornea (normally a clear windshield of the eye) appears cloudy, or ‘glassy’. The elevated pressure causes damage to the optic nerve leading to loss of vision.
Genetics
Inheritance
This is usually considered an autosomal recessive disorder. It can result from the inheritance of two mutations, one from each normal parent and therefore often appears in a horizontal pattern.
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
Only an ophthalmologist can make this diagnosis. However, a pediatrician or family doctor should also be a part of the team to rule out associated abnormalities elsewhere in the body. It is essential that the elevated pressure be controlled for blindness can result if it remains too high. The usual drugs used in adults for glaucoma may not be effective and surgery is often necessary.
Web Resources
Printer Friendly Version: Ctrl/Cmd+P