Higher estimates use a broader definition of familial ALS and examine the family history of people with ALS more thoroughly.In sporadic ALS, there is no family history of the disease. Sporadic ALS and familial ALS appear identical clinically and pathologically and are similar genetically; about 10% of people with sporadic ALS have mutations in genes that are known to cause familial ALS. In light of these parallels, the term "sporadic ALS" has been criticized as misleading because it implies that cases of sporadic ALS are only caused by environmental factors; the term "isolated ALS" has been suggested as a more accurate alternative.More than 20 genes have been associated with familial ALS, of which four account for the majority of familial cases: C9orf72 (40%), SOD1 (20%), FUS (1–5%), and TARDBP (1–5%). The genetics of familial ALS are better understood than the genetics of sporadic ALS; as of 2016, the known ALS genes explained about 70% of familial ALS and about 15% of sporadic ALS. Overall, first-degree relatives of an individual with ALS have a 1% risk of developing ALS. ALS has an oligogenic mode of inheritance, meaning that mutations in two or more genes are required to cause disease.ALS and frontotemporal dementia (FTD) are now considered to be part of a common disease spectrum (FTD–ALS) because of genetic, clinical, and pathological similarities. Genetically, C9orf72 repeat expansions account for about 40% of familial ALS and 25% of familial FTD.
Purtschers retinopathy is a disease where part of the eye (retina) is damaged. Usually associated with severe head injuries, it may also occur with other types of trauma, such as long bone fractures, or with several non-traumatic systemic diseases. However, the exact cause of the disease is not well understood. There are no treatments specific for Purtschers retinopathy, and the prognosis varies. The disease can threaten vision, sometimes causing temporary or permanent blindness. It is named for the Austrian ophthalmologist, Othmar Purtscher (1852–1927), who detected it in 1910 and described it fully in 1912. Presentation
Associated diseases
Severe head, chest, or long bone trauma
Acute pancreatitis
Amniotic fluid embolism
Chronic kidney failure
Dermatomyositis
Fat embolism syndrome
Scleroderma
Systemic lupus erythematosus (SLE)
Thrombotic thrombocytopenic purpura (TTP)

Pathophysiology
Purtschers retinopathy likely involves complex pathophysiology, with several contributing factors, including complement-mediated aggregates, fat, air, fibrin clots and platelet clumps. The diseases leads to the formation of cotton wool spots in the retina, a finding observed in several other diseases, and atrophy of the optic nerve. Diagnosis
Where trauma is involved, only a funduscopic examination of the back of the eye (retina) is necessary to make the diagnosis. Fluoroscein angiography may show a decrease in blood flow to the areas of whiteness in the retina. Treatment
It may be treated with triamcinolone in some cases. However, in general, there are no treatments for Purtschers retinopathy. If it is caused by a systemic disease or emboli, then those conditions should be treated. Prognosis
Purtschers retinopathy can lead to loss of vision, and recovery of vision may occur very little.