Familial Lichen Amyloidosis (Type IX) is a skin disorder in which faulty protein clumps known as amyloids form in the wave-like extensions between the upper two layers of skin. Skin patches with atypical texture or color are the predominant symptom of PLCA.
These patches distinguish three types of amyloidosis: macular, lichen, and nodular. Mutations in the IL31RA or OSMR genes can result in familial lichen amyloidosis (type IX). Moreover, the type 1 conditions are caused by mutations in the IL31RA gene. Additionally, macular and lichen are expected to be linked to diseases with comparable disease processes, and mutations in either gene are believed to be involved.