(progressive cones degeneration, generalized progressive cone dystrophy,  inherited cone dystrophy, cone rod dystrophy)

Prevalence: about 1/40,000. Group of congenital pathologies of the eye belonging to the group of pigmentary retinopathies involving the photosensitive cells (rods and cones) in the retina.

At least 30 types of cone dystrophies are described:

-        non-syndromic forms:

*        CRX gene mutations: 5 to 10 % of autosomal dominant forms; mutations of RIM1 and HRG4 genes have also been described

*        mutations of genes generally involved in dystrophies of the macula like ANCA4 (30 to 60 % of the autosomal recessive forms) [other mutations of that gene cause Stargardt disease (see this term)], or more rarely, the GUCA1A gene

*        mutations of genes generally involved in pigmentary retinopathies as RDS (less severe dominant autosomal forms) and RPGR (severe X-linked forms) genes

*        mutations of genes usually involved in Leber congenital amaurosis (see this term) as RPGRIP1 (recessive autosomal form), AIPL1 (dominant autosomal form) and GUCY2D genes

-        syndromic forms as Bardet-Biedl syndrome, spinocerebellar ataxia type 7 syndrome (see these terms), some cases of recessive  amelogenesis imperfecta (abnormality of the enamel of the teeth), hypotrichosis with juvenile dystrophy of the macula or   spondylometaphysar dysplasia (see this term).

This results in a gradual loss of vision. The first symptoms are: reduction in visual acuity (central scotoma), loss of color vision, and later photophobia. Most of the patients are visually impaired or blind around 30-40 years of age.

On fundoscopic examination, retinal pigmentary deposits are mainly localized at the level of the macula.

Anesthetic implications:

visually impaired patients

References :

-        Hamel CP.
Cone rod dystrophies.
Orphanet J Rare Diseases 2007 2 :7 doi : 10.1186/1750-1172-2-7

Updated: April 2018