Phakomatoses, also known neurocutaneous syndromes, are a group of multisystemic diseases that most prominently affect structures primarily derived from the ectoderm such as the central nervous system, skin and eyes. The majority of phakomatoses are single-gene disorders that may be inherited in an autosomal dominant, autosomal recessive or X-linked pattern. Presentations may vary dramatically between patients with the same particular syndrome due to mosaicism, variable expressivity, and penetrance.Many phakomatoses are caused by mutations which alter functioning of the RAS–mitogen-activated protein kinase (MAPK) pathway that regulates cellular growth, differentiation, proliferation and death. This results in a tendency for individuals with these mutations to develop various types of benign or malignant tumors depending on the particular mutation. The presence of these tumors may result in functional and/or cosmetic problems depending on their type and location. History
The term phakomatosis originated in 1923, when the Dutch ophthalmologist van der Hoeve used the term phakoma to refer to a "mother spot" or birthmark, a physical characteristic common to patients with tuberous sclerosis and neurofibromatosis that he examined. The term phakomatoses was derived from phakos, the Greek term for birthmark. He originally used the phrase to describe two diseases: neurofibromatosis and tuberous sclerosis. This term later became imprecise when van der Hoeve also used it to include those with Sturge-Weber syndrome as they do not have similar lesions on the skin. In addition, the term phakomatosis makes no reference to the central nervous system involvement.
Younger patients start out having unimpaired vision, but it starts to deteriorate at a young age and does so slowly. If vision is able to improve with the use of glasses, they should be worn to help facilitate concept development. Retinal degeneration cannot be ameliorated with glasses.The type of therapy needed for each individual varies, as not every affected individual would benefit from speech, physical, and occupational therapies. The type of therapy for each person is highly individualized. Individuals who have Cohen syndrome may also benefit from psychosocial support.Many people who have Cohen syndrome also have neutropenia which is a condition in which an individual has an abnormally low number of white blood cells called neutrophils. Having this condition may make these individuals susceptible to infections. Granulocyte-colony stimulating factor (G-CSF) is one possible treatment for neutropenia.Monitoring weight gain and growth is crucial, as well as annual ophthalmologic and hematologic evaluations and checkups. While there are treatments available to people with Cohen syndrome, there are no known cures for the disease. Prevalence
Over the past several years, there have been approximately 50 new cases worldwide. There are population groups with this condition in Australia, New Zealand, the UK and the US. It still seems to go undiagnosed, leaving the number of known cases less than 500. Etymology
The syndrome is named after Michael Cohen, William Pepper and Jaroslav Cervenka, who researched the illness. References
External links

GeneReview/NIH/UW entry on Cohen syndrome