OMIM ID:
Anterior Segment Dysgenesis 8
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
This is a congenital anterior segment dysplasia syndrome with considerable clinical heterogeneity. Iris hypoplasia with transillumination, corectopia, iridodenesis, and iridocorneal adhesions are often seen. Intraocular pressure may be elevated in older individuals. Ectopia lentis is often present. Lenticular opacities consisting primarily of posterior cortical opacification are common. Visual acuity varies from 6/6 to 6/24.
No foveal hypoplasia is present but one of four reported patients was described with bilateral optic nerve dysplasia.
Systemic Features
No systemic abnormalities have been reported.
Genetics
Inheritance
Three families with 4 affected individuals with similar clinical features have been reported with homozygous or compound heterozygous mutations in the CPAMD8 gene (19p13.11).
A single male patient of native American/French Canadian background with somewhat similar clinical features has been reported with compound heterozygous mutations in the CYP1B1 gene (2p22.2) but this is likely a unique condition (Anterior Segment Dysgenesis 6).
The genes FOXE3 and PAX6 are characterized as transcription factors and play important roles in ocular development. However, while mutations in these are frequently found in patients with dysgenesis of the anterior chamber they often cause more widespread ocular and systemic anomalies (e.g., Gillespie syndrome [206700]). Therefore in this database the anterior chamber constellations of anomalies associated with mutations in these genes are not considered to be simplex conditions.
See also related disorders iridogoniodysgenesis type 1 (601631) and type 2 (137600), and anterior segment mesenchymal dysgenesis (107250).
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.