achromatopsia

Stationary cone dystrophy is usually present in infancy or early childhood: symptoms usually remain the same throughout life, and patients maintain normal rod function. In progressive cone dystrophy, onset is usually in infancy or early adulthood, and patients often develop rod dysfunction with associated symptoms that worsen over time.

Stationary cone dystrophies are best described as cone dysfunction syndromes, as a dystrophy often describes a progressive process.
The cone dysfunction syndromes are complete and incomplete achromatopsia, oligocon trichromacy, cone monochromatism, blue cone monochromatism, and Bornholm eye disease.

THEComplete achromatopsia (ACHM), typical achromatopsia or rod monochromatism, is a stationary disease in which there is an absence of functioning cones in the retina, with an incidence ranging from approximately 1 in 30 to 000 in 1. an autosomal recessive mode of inheritance and has been associated with mutations in five genes (GNAT50, PDE000C, PDE2H, CNGA6 and CNGB6), which encode key components of the cone phototransduction cascade. The patient with complete achromatopsia usually presents with pendular nystagmus, color blindness, poor visual acuity, photophobia, and a hypermetropic refractive error.

Previously, before the pathogenesis of blue cone monochromatism (BCM) was identified, BCM was known as incomplete or atypical X-linked achromatopsia. However, the term incomplete / atypical achromatopsia is best reserved for the description of individuals with autosomal recessive disease in which the phenotype is a variant of complete achromatopsia. Individuals with incomplete achromatopsia (atypical achromatopsia) retain residual color vision and slightly better visual acuity than those with complete achromatopsia. As with the complete form, mutations in the CNGA3 gene, which encodes the cGMP cation channel α subunit in cones, have been identified in subjects with incomplete achromatopsia.