OMIM ID:
Glaucoma, Congenital Primary B
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
Type B congenital glaucoma is considerably more rare than type A and may be more common in Middle Eastern families. Few families have been reported but the clinical features are similar: elevated intraocular pressure in infancy or early childhood, photophobia, and cloudy corneas (see Glaucoma, Congenital Primary A [231300] for a more complete description of the phenotype).
Systemic Features
No systemic abnormalities are associated.
Genetics
Inheritance
This is an autosomal recessive disorder caused by a mutation in GLC3B mapped to a locus at 1p36.2-p36.1. Type A congenital glaucoma (231300) is caused by a mutation in CYP1B1 and type D by mutations in LTBP2 (613086). A locus at 14q24.3 has been asssociated with another form of congenital glaucoma (613085; type C) but the nature of the gene is unknown. Mutations in TEK are responsible for congenital glaucoma type GLC3E.
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.