Many eye diseases have a genetic basis and – like genetic hearing impairment – display extensive genetic heterogeneity, that is, many genes are known whose mutations cause the disease. This particularly applies to retinal degeneration (synonymously referred to as retinal dystrophies, retinopathies): Mutations in more than 200 genes account for non-syndromic (Leber congenital amaurosis, LCA; retinitis pigmentosa, RP; cone-(rod) dystrophy, CD/CRD; macular dystrophy, MD; congenital stationary nightblindness, CSNB) and various syndromes involving the retina. Furthermore, many genes are associated with congenital nystagmus, cataract, ocular (-cutaneous) albinism, retinal detachment, optical atrophy, anophthalmia and microphthalmia and other defects of eye development.
The knowledge of the underlying gene defect has far-reaching consequences for the individual medical care and guidance of patients and their families. It may not only confirm the genetic diagnosis and hence inform about the recurrence risk in the family. It becomes apparent that certain eye disease – as is already the case for RPE65-related retinal dystrophy – may be accessible to (gene) therapy approaches that specifically target the respective gene or its mutation.
Familial clustering of cancers may indicate that hereditary factors play an important role for cancer development in such families. Genetic counselling and molecular genetic diagnostics may enable targeted preventive screening measures and might be important for individual treatment in some tumour entities.