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The following introduction and examples are taken from the original article:Phakomatoses (or neuro-oculo-cutaneous syndromes, neurocutaneous disorders) are multisystem disorders that have characteristic central nervous system, ocular, and cutaneous lesions of variable severity. The skin and the brain have a common ectodermal origin, so there are many genetic and acquired diseases that affect both tissues. However, in some conditions, such as von Hippel-Lindau disease, ectodermal presentation is minimal.

The term, from the Greek φακός, phakos, "spot, lens", suffix-(o)ma (-ωμα) and the suffix -osis, also called "Mother's spot" or "Birth mark" was introduced by Jan van der Hoeve in 1920, before the distinct genetic basis of each of these diseases was understood.

Examples
Phakomatoses are inconsistently defined, and there is a lack of consensus about what conditions are included in this category.

Conditions included are:
 * Ataxia telangiectasia
 * Incontinentia pigmenti
 * Neurofibromatosis
 * Nevoid basal cell carcinoma syndrome
 * Sturge-Weber syndrome
 * Tuberous sclerosis
 * Wyburn-Mason syndrome (Bonnet–Dechaume–Blanc syndrome)
 * von Hippel-Lindau disease

Signs and Symptoms
Phakomatoses are multi-system disorders that primarily cause changes in the central nervous system, ocular system, and lesions on skin. Four of the disorders being compared are ataxia telangiectasia, Sturge-Weber syndrome, tuberous sclerosis, and neurofibromatosis. These diseases all have commonalities among their signs and symptoms that cause them to be classified as phakomatoses.

Skin

 * Sturge-Weber syndrome: birthmark known as a port-wine stain located on the forehead, upper eyelid of one side of the face, or both sides of the face.
 * Tuberous sclerosis: dermatological abnormalities such as facial angiofibromas, forehead plaques, and periungual fibromas.


 * Neurofibromatosis: brownish dermatological spots.
 * Ataxia telangiectasia: usually have clusters of blood vessels that form on the surface of the skin.

Central Nervous System

 * Sturge-Weber syndrome: can experience intellectual disability or developmental delays. This is due to cerebral malformations, known as ipsilateral leptomeningeal angioma, and cerebral blood flow abnormalities, which can also cause headaches. Individuals are also prone to seizures that begin when the person is an infant and tend to intensify with age. These convulsions usually occur on the opposite side of the body from where their birthmark is located.
 * Tuberous sclerosis: likely to be diagnosed with Attention-Deficit Hyperactivity Disorder (ADHD) as well as experience behavioral problems and learning disabilities. They can also experience seizures due to development delays and brain lesions.
 * Neurofibromatosis: experience learning and behavioral issues.
 * Ataxia telangiectasia: usually have slurred speech. />

Eyes

 * Sturge-Weber syndrome: glaucoma, which causes increased pressure in the eye and choroidal lesions.
 * Tuberous sclerosis: retinal lesions which appear grey, yellow, or white.
 * Neurofibromatosis: impaired vision as a result of brain tumors that develop on the optic nerve pathway. Individuals also have affected peripheral vision due to the development of peripheral nerve tumors.
 * Ataxia telangiectasia: clusters of blood vessels that can be seen in the eyes but usually do not affect vision. Neurological problems can also cause irregular eye movements.

Skeletal

 * Sturge-Weber syndrome: muscle weakness, specifically on the opposite side of where the port-wine stain is located on the body.
 * Neurofibromatosis: skeletal abnormalities and abnormal growths on the spinal cord.
 * Ataxia telangiectasia: can develop deformities of their feet and can experience uncoordinated movements and muscle twitches./>

Immune System

 * Ataxia telangiectasia: weakness in immune system, which causes an increased probability of developing various types of cancers./>

Tumors

 * Tuberous sclerosis: can develop benign tumors in the kidneys, lungs, and the heart.

Hearing

 * Neurofibromatosis: usually begin to lose their hearing in young adulthood.

Lungs

 * Tuberous sclerosis: experience cysts on the lungs, which replace the normal parenchyma, making it more difficult for the individual to breathe.


 * Ataxia telangiectasia: at a high risk for developing lung disease.

Nutrition

 * Ataxia telangiectasia: difficulty eating and swallowing, which can develop poor nutrition.

Cause/Mechanism
All diseases that fall under the category of phakomatosis are caused by genetic abnormalities. Both tuberous sclerosis and neurofibromatosis are autosomal dominant mutations, while ataxia telangiectasia is an autosomal recessive disease. Autosomal dominant diseases only require one copy of the mutated gene in order for the child to have the affected disease. For someone to have an autosomal recessive disease, they must have two copies of the defective gene, one from each parent.
 * Sturge-Weber syndrome: due to a mutation in the GNAQ gene. This gene is responsible for clearing the network of nerves around the head of a fetus during the 9th week of development. The functional abnormality of not clearing these nerves reduces the amount of oxygen and blood flowing to the brain and can cause brain tissue development problems.
 * Tuberous sclerosis: due to a mutation or defect in either the TSC1 or TSC2 gene which both code for tumor suppressors. TSC1 and TSC2 work in a complex together to inhibit activation of the kinase mTOR. A loss of regulation of mTOR generates enlarged cells, abnormal differentiation, and abnormal development.


 * Neurofibromatosis: due to a germline mutation in the NF1 and NF2 tumor suppressor gene. This leads to flawed cell regulation and abnormal cell proliferation.
 * Ataxia telangiectasia: due to a mutation in the ATM gene. A functional ATM gene is responsible for development of body systems, cell division, and DNA repair. The mutation causes cellular death in cerebellar cells, which are the most susceptible. In addition, there is also loss of cerebellar cells which lead to motor function abnormalities.

Diagnosis
Despite the many similarities between the examples of phakomatosis, there are many different methods of diagnosis. A common way to diagnose neurofibromatosis, Sturge-Weber syndrome, and tuberous sclerosis is an MRI or CT scan. These are both ways of taking brain scans to look for any abnormalities. Genetic testing is another common way to diagnose these disorders, excluding ataxia telangiectasia. Additional ways of diagnosis for each disease are listed below:
 * Tuberous sclerosis: diagnosed by an ultrasound of the kidney, heart, or liver.
 * Neurofibromatosis: diagnosed through the use of radiographs.
 * Ataxia telangiectasia: recommended to be diagnosed with a test determining the absence, or reduced activity, of the ATM protein.

Treatment

 * Sturge-Weber syndrome: treated partially with a laser treatment that aims at lightening or removing birthmarks. Additionally, symptoms are managed with medication to control seizures, physical therapy, and several different educational therapies.
 * Tuberous sclerosis: variety of management options based on the symptoms one is experiencing; these may vary behaviorally, cognitively, and neurologicall
 * Neurofibromatosis: commonly treated with biological treatments, such as surgery, chemotherapy, or radiation.
 * Ataxia telangiectasia: managed through occupational therapy, speech therapy, medication for the neurological symptoms, immunizations, antibiotics for respiratory infections, chest physiotherapy to manage excess mucus, muscle training that aims at strengthening the respiratory muscles, eye surgery, and braces for the feet.

Prognosis

 * Sturge-Weber syndrome: individuals can experience birthmarks and atrophy in the cerebral cortex without symptoms. Symptomatic individuals will develop seizures within their first year of life. If the treatment for seizures is ineffective it is likely they will have increased intellectual impairment.
 * Tuberous sclerosis: individuals that experience mild symptoms have normal life expectancies. Those with more severe symptoms suffer from more serious disabilities. All individuals are at risk for developing life-threatening brain tumors, or kidney lesions. In addition, patients are also at risk for lymphangioleiomyomatosis (LAM) which may require lifelong monitoring.
 * Neurofibromatosis: individuals can experience symptoms in two ways, each with varying outcomes. Individuals with a mutation in the NF1 gene will experience mild symptoms and children are able to live a normal life. Individuals with a mutation in the NF2 gene experience damage to cranial nerves, which can cause severe health issues therefore a less positive prognosis.
 * Ataxia telangiectasia: those affected have an average life expectancy of about 25 years. Many individuals will eventually succumb to the conditions associated with the disease, such as lung disease and different types of cancers.

Epidemiology

 * Sturge-Weber syndrome: prevalent in 1 in 50,000 newborns.
 * Tuberous sclerosis: affects all ages, races, and genders equally. It has a prevalence rate of 7-12 in 100,000 people, however many cases go undetected.
 * Neurofibromatosis: prevalent in 1 in 2,500 live births. It is more common in boys than girls and individuals with neurofibromatosis are at higher risk for early mortality.
 * Ataxia telangiectasia: prevalent in between 1 in 40,000 and 1 in 100,000 live births,/> with symptoms beginning to present between ages two and five. In addition, it affects all races and ethnicities equally.