In other species: dog

Categories: Vision / eye phene

Possibly relevant human trait(s) and/or gene(s)s (MIM numbers): 613829 (trait) , 602225 (gene)

Links to MONDO diseases:

• MONDO:0013449: Leber congenital amaurosis 7

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal dominant

Considered a defect: yes

Key variant known: yes

Year key variant first reported: 2010

Species-specific name: Progressive retinal dystrophy/atrophy; Cone-rod dystrophy/dysplasia

Species-specific symbol: Rdy

Molecular basis: Menotti-Raymond et al. (2010) provided convincing evidence that this form of retinopathy, so long studied, is the result of a frameshift mutation due to a single base deletion in the cone-rod homeobox-containing gene (CRX).

Clinical features: Clinically, affected kittens can be recognised by the age of 4-5 weeks; they have a slower pupillary light reflex and pupil dilation. 6 weeks old kittens may have a pendular nystagmus, and by 7-8 weeks retinal changes can be observed with ophthalmoscopy in the centralis region. Mottling and grey discolouration of the retina will be observed, and these changes extend to the periphery over a few weeks. By 12 weeks, affected kittens have a generalised hyper-reflectivity of the tapetal fundus, mottling and depigmentation of the non-tapetal area and vascular attenuation. Signs of progressive blindness occur in the first 4 months of life. (Narfström et al., 2011)

IT thanks DVM student Jaimie McElroy, who provided the basis of this contribution in May 2023.

Pathology: Occelli et al. (2016) provided a comprehensive description of the pathogenesis of the disorder resulting from the frameshift variant.

Breeds: Abyssinian (Cat) (VBO_0100000), Somali (Cat) (VBO_0100229).

Associated gene: