Daniel de Boer, Founder and CEO of ProQR, discusses Leber’s congenital amaurosis (LCA), the most common genetic cause of childhood blindness that affects about 15,000 patients in the Western world. LCA leads to poor vision and blindness for which there is currently no approved treatment. The disease usually appears in the first year of life and is characterized by progressive loss of vision. In some cases, patients eventually become severely visually impaired and depending on the mutation, complete loss of vision will occur during early childhood.

In LCA, a process called photo transduction is disrupted in the light detecting cells (rods and cones) in the retina, due to a mutation in a specific gene. Because these cells cannot perform their function properly patients experience nystagmus (involuntary eye movement) and severely impaired visual function.

Leber congenital amaurosis primarily affects the retina. People with this condition typically have severe visual impairment beginning in infancy. Other features include photophobia, involuntary movements of the eyes (nystagmus), and extreme farsightedness. The pupils also do not react normally to light. Additionally, the cornea may be cone-shaped and abnormally thin (keratoconus). Franceschetti’s oculo-digital sign is characteristic of Leber congenital amaurosis. This sign consists of poking, pressing, and rubbing the eyes with a knuckle or finger. Different subtypes have been described. The different subtypes are caused by mutations in different genes. Some of these subtypes are also distinguished by their patterns of vision loss and related eye abnormalities. Treatment includes correction farsightedness and use of low-vision aids when possible.