However, this has been shown to be false, with the spacing of prolines and charged residues having been shown to be critical in amyloid formation.Bioinformatic screens have predicted that over 250 human proteins contain prion-like domains (PrLD). These domains are hypothesized to have the same transmissible, amyloidogenic properties of PrP and known fungal proteins. As in yeast, proteins involved in gene expression and RNA binding seem to be particularly enriched in PrLDs, compared to other classes of protein. In particular, 29 of the known 210 proteins with an RNA recognition motif also have a putative prion domain. Meanwhile, several of these RNA-binding proteins have been independently identified as pathogenic in cases of ALS, FTLD-U, Alzheimers disease, and Huntingtons disease. Role in neurodegenerative disease
The pathogenicity of prions and proteins with prion-like domains is hypothesized to arise from their self-templating ability and the resulting exponential growth of amyloid fibrils. The presence of amyloid fibrils in patients with degenerative diseases has been well documented. These amyloid fibrils are seen as the result of pathogenic proteins that self-propagate and form highly stable, non-functional aggregates. While this does not necessarily imply a causal relationship between amyloid and degenerative diseases, the toxicity of certain amyloid forms and the overproduction of amyloid in familial cases of degenerative disorders supports the idea that amyloid formation is generally toxic.Specifically, aggregation of TDP-43, an RNA-binding protein, has been found in ALS/MND patients, and mutations in the genes coding for these proteins have been identified in familial cases of ALS/MND.
Primary cutaneous amyloidosis is a form of amyloidosis associated with oncostatin M receptor. This type of amyloidosis has been divided into the following types:: 520 
Macular amyloidosis is a cutaneous condition characterized by itchy, brown, rippled macules usually located on the interscapular region of the back. : 521  Combined cases of lichen and macular amyloidosis are termed biphasic amyloidosis, and provide support to the theory that these two variants of amyloidosis exist on the same disease spectrum. Lichen amyloidosis is a cutaneous condition characterized by the appearance of occasionally itchy lichenoid papules, typically appearing bilaterally on the shins. : 521 
		
		
Nodular amyloidosis is a rare cutaneous condition characterized by nodules that involve the acral areas. : 521

See also
Amyloidosis
List of cutaneous conditions

References


== External links ==