OMIM ID:
Retinal Dystrophy With Or Without Extraocular Anomalies
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
Progressive deterioration of rod and cone function is characteristic of this condition which is clinically manifest as some variation of pigmentary retinopathy. Early (second decade) pigmentary changes resemble retinitis pigmentosa but in the fourth and fifth decades they resemble a peripheral pattern-like reticular dystrophy. Central chorioretinal atrophy has been described in some patients. The ERG responses are abnormal suggesting loss of the photoreceptors.
Systemic Features
Extraocular anomalies are highly variable ranging from a mild intellectual disability in some patients, to thyroid goiter and nodules, and primary ovarian insufficiency. Sensorineural hearing loss was present in one family and one patient had pulmonary fibrosis.
Genetics
Inheritance
Homozygous missense mutations in the RCBTB1 gene (13q14) seem to be responsible for this condition. Six families have been reported.
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.