OMIM ID:
Foveal Hypoplasia 2
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
The cardinal feature in this condition is foveal hypoplasia which is characterized by the lack of a foveal depression and continuity of all neurosensory layers across the foveal area as revealed by OCT. This is accompanied by poor visual acuity, nystagmus, and strabismus. Hypopigmentation of the immediate area has also been reported in some patients. Visual acuity in one study of 9 patients ranged from 20/50 to 20/200. The ERG and flash VEP can be normal. Color vision has been described as normal in some individuals.
Dysgenesis of the anterior segment seems to be family-specific and consists of Axenfeld anomaly or embryotoxon.
Systemic Features
In most cases the only features are foveal hypoplasia with or without anterior chamber anomalies. Three affected sisters in one family were reported to have mild developmental delay.
Genetics
Inheritance
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.