Leber Congenital Amaurosis

Leber`s congenital amaurosis in felines is a severe hereditary disease characterized by progressive degeneration of the retina from an early age. It is caused by mutations in the AIPL1 gene, which encodes a protein crucial for the development and function of photoreceptors in the retina.

Symptoms

The first clinical signs usually appear around the second and third week of life, manifesting as a reduction in the speed and extent of direct and consensual pupillary reflexes, which became more noticeable with age. Over time, pupillary dilation becomes slower and the horizontal pupil diameter increases. In addition, affected cats experience loss of the glare reflex. By 16 weeks of age, most affected cats develop total blindness under normal light conditions and show rapid retinal degeneration.

Disease Management

There is no known effective treatment for this disease, so management focuses on providing symptomatic support and improving the quality of life of affected cats.

Genetic basis

This disease follows an autosomal recessive mode of inheritance. Autosomal recessive inheritance means that the cat, regardless of sex, must receive two copies of the mutation or pathogenic variant to be at risk of developing the disease. Both parents of an affected cat must carry at least one copy of the mutation. Animals with only one copy of the mutation are not at increased risk of developing the disease, but may pass the mutation on to future generations. Breeding between cats carrying genetic variants that may cause disease is not recommended, even if they do not show symptoms.

Technical report

Leber`s congenital amaurosis is a heterogeneous group of retinal dystrophies that manifest from an early age, being classified as the most severe form of retinopathy. The AIPL1 gene, which encodes aryl-hydrocarbon-like interacting protein, plays a crucial role in the development and proper function of cone and rod photoreceptors in the retina. The variant identified in AIPL1, c.577C > T, results in the loss of approximately 40% of the resulting functional protein. The study by Lyons et al. (2016) establishes the Persian cat with progressive retinal atrophy, a carrier of this genetic variant in AIPL1, as a new animal model to study Leber congenital amaurosis.

Most affected breeds

Persian

Bibliography

Lyons LA, Creighton EK, Alhaddad H, et al. Whole genome sequencing in cats identifies new models for blindness in AIPL1 and somite segmentation in HES7. BMC Genomics. 2016 Mar 31