Leber Congenital Amaurosis 13 is an inherited retinal dystrophy that is characterized by involuntary movements of the eyes (nystagmus), sluggish pupillary responses, roving eye movement, extreme farsightedness (hyperopia), crossed eyes (strabismus), and sensitivity to light (photophobia).  LCA patients may also suffer from keratoconus, a condition where the cornea is abnormally thin and cone shaped.  The disorder results in severe visual impairment and electroretinogram studies of affected patients show little to no electrical activity in the retina.  A key symptom of the disorder in children is Franceschetti’s oculo-digital sign, a tendency to poke, press and rub the eyes.  This often results in deep-set, sunken eyes known as enophthalmus. Other symptoms that can develop include cataracts, glaucoma and corneal problems.

The disorder usually affects children at birth or within the first year of life. LCA affects about 2 to 3 newborns per 100,000 and is one of the most common causes of blindness in children.  LCA is diagnosed based on ophthalmological examinations, electroretinogram studies and genetic mutation tests.  While there is currently no cure for LCA, the disorder can be managed by the use of low vision optical aids to maximize visual function.  Routine ophthalmic follow-ups are also recommended to evaluate the presence of cataract and glaucoma. 

LCA13 follows an autosomal recessive pattern of inheritance.  It is caused by homozygous or compound heterozygous mutations in the RDH12 gene.  The RDH12 protein is a retinol dehydrogenase involved in the retinol metabolic process and hence is essential to photoreceptor cell maintenance.  More than a dozen mutations in the RDH12 gene have been found to result in LCA13.