performed a screen on 402 AMD patients and revealed a statistically significant correlation between mutations in fibulin-5 and incidence of the disease. Mitochondrial-related gene polymorphisms such as that in the MT-ND2 molecule, predicts wet AMD. Pathophysiology
The pathogenesis of age-related macular degeneration is not well known, although some theories have been put forward, including oxidative stress, mitochondrial dysfunction, and inflammatory processes. The imbalance between the production of damaged cellular components and degradation leads to the accumulation of harmful products, for example, intracellular lipofuscin and extracellular drusen. Incipient atrophy is demarcated by areas of retinal pigment epithelium (RPE) thinning or depigmentation that precede geographic atrophy in the early stages of AMD. In advanced stages of AMD, atrophy of the RPE (geographic atrophy) and/or development of new blood vessels (neovascularization) result in the death of photoreceptors and central vision loss. In the dry (nonexudative) form, drusen accumulates between the retina and the choroid, causing atrophy and scarring to the retina. In the wet (exudative) form, which is more severe, blood vessels grow up from the choroid (neovascularization) behind the retina which can leak exudate and fluid and also cause hemorrhaging. Early work demonstrated a family of immune mediators was plentiful in drusen. Complement factor H (CFH) is an important inhibitor of this inflammatory cascade, and a disease-associated polymorphism in the CFH gene strongly associates with AMD. Thus an AMD pathophysiological model of chronic low grade complement activation and inflammation in the macula has been advanced.
Trichoepithelioma is a neoplasm of the adnexa of the skin. Its appearance is similar to basal cell carcinoma. One form has been mapped to chromosome 9p21. Types
Trichoepitheliomas may be divided into the following types:: 672 
Multiple familial trichoepithelioma
Solitary trichoepithelioma
Desmoplastic trichoepithelioma

Pathology
Trichoepitheliomas consists of nests of basaloid cells, with palisading. They lack the myxoid stroma and artefactual clefting seen in basal cell carcinoma. Mitoses are uncommon when compared to basal cell carcinoma. Diagnosis
Trichoepiteliomas often contain Merkel cells; an immunostain for CK20 can be used to demonstrate this. See also
Trichoblastoma
Pilomatricoma
CYLD cutaneous syndrome
List of cutaneous conditions
List of cutaneous neoplasms associated with systemic syndromes

References


== External links ==