Tuberous sclerosis

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Tuberous sclerosis
Other namesTuberous sclerosis complex (TSC),
Bourneville disease, Bourneville-Pringle disease [1]
Symptoms and signs of tuberous sclerosis.png
Main symptoms and signs of tuberous sclerosis
Specialty Neurology, medical genetics
Prognosis normal life expectancy
Frequency7 to 12 per 100,000 [2]

Tuberous sclerosis complex (TSC) is a rare multisystem autosomal dominant genetic disease that causes non-cancerous tumours to grow in the brain and on other vital organs such as the kidneys, heart, liver, eyes, lungs and skin. A combination of symptoms may include seizures, intellectual disability, developmental delay, behavioral problems, skin abnormalities, lung disease, and kidney disease.

Contents

TSC is caused by a mutation of either of two genes, TSC1 and TSC2 , which code for the proteins hamartin and tuberin, respectively, with TSC2 mutations accounting for the majority and tending to cause more severe symptoms. [3] These proteins act as tumor growth suppressors, agents that regulate cell proliferation and differentiation. [4]

Prognosis is highly variable and depends on the symptoms, but life expectancy is normal for many. [4]

The prevalence of the disease is estimated to be 7 to 12 in 100,000. [2] The disease is often abbreviated to tuberous sclerosis, which refers to the hard swellings in the brains of patients, first described by French neurologist Désiré-Magloire Bourneville in 1880. [5]

Signs and symptoms

The physical manifestations of TSC are due to the formation of hamartia (malformed tissue such as the cortical tubers), hamartomas (benign growths such as facial angiofibroma and subependymal nodules), and very rarely, cancerous hamartoblastomas. The effect of these on the brain leads to neurological symptoms such as seizures, intellectual disability, developmental delay, and behavioral problems.[ citation needed ]

Neurological

TSC in MRI Tuberoese Sklerose 1J T2 axial2.png
TSC in MRI

Three types of brain tumours are associated with TSC:[ citation needed ]

Classic intracranial manifestations of TSC include subependymal nodules and cortical/subcortical tubers. [6]

The tubers are typically triangular in configuration, with the apex pointed towards the ventricles, and are thought to represent foci of abnormal neuronal migration. The T2 signal abnormalities may subside in adulthood, but will still be visible on histopathological analysis. On magnetic resonance imaging (MRI), TSC patients can exhibit other signs consistent with abnormal neuron migration such as radial white matter tracts hyperintense on T2WI and heterotopic grey matter.[ citation needed ]

Subependymal nodules are composed of abnormal, swollen glial cells and bizarre multinucleated cells which are indeterminate for glial or neuronal origin. Interposed neural tissue is not present. These nodules have a tendency to calcify as the patient ages. A nodule that markedly enhances and enlarges over time should be considered suspicious for transformation into a subependymal giant cell astrocytoma, which typically develops in the region of the foramen of Monro, in which case it is at risk of developing an obstructive hydrocephalus.

A variable degree of ventricular enlargement is seen, either obstructive (e.g. by a subependymal nodule in the region of the foramen of Monro) or idiopathic in nature.[ citation needed ]

Neuropsychiatric

About 90% of people with TSC develop a range of neurodevelopmental, behavioural, psychiatric, and psychosocial difficulties. The "TSC‐associated neuropsychiatric disorders" are abbreviated TAND. These difficulties are less frequently identified and thus undertreated when compared with the neurological symptoms. [7] Most problems are associated with more severe intellectual delay or associated with childhood and adolescence, and some (for example depressed mood) may be unreported if the person is unable to communicate. TAND can be investigated and considered at six levels: behavioural, psychiatric, intellectual, academic, neuropsychological, and psychosocial. [7]

Behavioural problems most commonly seen include overactivity, impulsivity and sleeping difficulties. Also common are anxiety, mood swings, and severe aggression. Less common are depressed mood, self-injury, and compulsive behaviours. [7]

People with TSC are frequently also diagnosed with psychiatric disorders: autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), anxiety disorder and depressive disorder. TSC is one of the most common genetic causes of autism spectrum disorder, which affects nearly half of people with TSC. ASD is more common in TSC2 than TSC1 and more common with earlier and more severe epilepsy, and with lower intellectual ability. ADHD is nearly as frequently seen in TSC as ASD (up to half of all people with TSC). Anxiety and depressive disorders, when they occur, are typically diagnosed in early adulthood and among those intellectually able to express their moods. [7]

The intellectual ability of people with TSC varies enormously. About 40–50% have a normal IQ. A normal IQ is much more commonly seen in TSC1 than TSC2, and profound intellectual disability seen in 34% of TSC2 compared with 10% of TSC1 in one study. Many studies have examined whether early onset, type and severity of epilepsy associates with intellectual ability. Academic issues occur even in people with TSC who have normal intellectual ability. These are often specific learning disorders such as dyscalculia (understanding mathematics), but also include other aspects affecting school life such as anxiety, lack of social skills or low self-esteem. [7]

About half of people with TSC, when assessed for neuropsychological skills, are in the bottom 5th percentile in some areas, which indicates a severe impairment. These include problems with attention (for example, being able to concentrate on two separate things like looking and listening), memory (particularly recall, verbal and spatial working memory) and executive function (for example, planning, self-monitoring, cognitive flexibility). [7]

The psychosocial impacts of TSC include low self-esteem and self-efficacy in the individual, and a burden on the family coping with a complex and unpredictable disorder. [7]

Kidneys

Computed tomography showing multiple angiomyolipomas of the kidney in a patient with lung lymphangioleiomyomatosis on CT: suspected TSC Angiomyolipome TubSklerose cor.jpg
Computed tomography showing multiple angiomyolipomas of the kidney in a patient with lung lymphangioleiomyomatosis on CT: suspected TSC

Between 26% and 80% of TSC patients have benign tumors of the kidneys called angiomyolipomas, with hematuria being the most frequent presenting symptom. [8] TSC angiomyolipomas differ from non-TSC angiomyolipomas in age of presentation (31.5 years vs 53.6 years), mean tumor size (8.2 cm vs 4.5 cm), and percentage of cases requiring surgical intervention (50% vs 28%). [8] Although benign, an angiomyolipoma larger than 4 cm is at risk for a potentially catastrophic hemorrhage, either spontaneously or with minimal trauma.[ citation needed ]

Lungs

Patients with TSC can develop progressive replacement of the lung parenchyma with multiple cysts, known as lymphangioleiomyomatosis (LAM). Recent genetic analysis has shown that the proliferative bronchiolar smooth muscle in TSC-related lymphangioleiomyomatosis is monoclonal metastasis from a coexisting renal angiomyolipoma. Cases of TSC-related lymphangioleiomyomatosis recurring following lung transplant have been reported. [9]

Heart

Small tumours of the heart muscle, called cardiac rhabdomyomas, are rare in the general population (perhaps 0.2% of children) but very common in people with TSC. Around 80% of children under two-years-old with TSC have at least one rhabdomyoma, and about 90% of those will have several. The vast majority of children with at least one rhabdomyoma, and nearly all children with multiple rhabdomyomas will be found to have TSC. Prenatal ultrasound, performed by an obstetric sonographer specializing in cardiology, can detect a rhabdomyoma after 20 weeks. Rhabdomyoma vary in size from a few millimetres to several centimetres, and are usually found in the lower chambers (ventricles) and less often in the upper chambers (atria). They grow in size during the second half of pregnancy, but regress after birth, and are seen in only around 20% of children over two years old. [10]

Most rhabdomyomas cause no problems but some may cause heart failure in the foetus or first year of life. Rhabdomyomas are believed to be responsible for the development of heart arrhythmia later in life, which is relatively common in TSC. Arrhythmia can be hard to spot in people with TSC, other than by performing routine ECG. For example, arrhythmia may cause fainting that is confused with drop seizures, and symptoms of arrhythmia such as palpitations may not be reported in an individual with developmental delay. [10]

Skin

A case of tuberous sclerosis showing facial angiofibromas in characteristic butterfly pattern. Patient with facial angiofibromas caused by tuberous sclerosis.jpg
A case of tuberous sclerosis showing facial angiofibromas in characteristic butterfly pattern.
From top to bottom: Hypopigmented macules, Shagreen patch and periungual fibroma of tuberous sclerosis. Hypopigmented macules, Shagreen patch and periungual fibroma of tuberous sclerosis.png
From top to bottom: Hypopigmented macules, Shagreen patch and periungual fibroma of tuberous sclerosis.

Some form of dermatological sign is present in 96% of individuals with TSC. Most cause no problems, but are helpful in diagnosis. Some cases may cause disfigurement, necessitating treatment. The most common skin abnormalities include:

Eyes

Retinal lesions, called astrocytic hamartomas (or "phakomas"), which appear as a greyish or yellowish-white lesion in the back of the globe on the ophthalmic examination. Astrocytic hamartomas can calcify, and they are in the differential diagnosis of a calcified globe mass on a CT scan. [13]

Nonretinal lesions associated with TSC include:

Pancreas

Pancreatic neuroendocrine tumours have been described in rare cases of TSC. [14]

Variability

Individuals with TSC may experience none or all of the clinical signs discussed above. The following table shows the prevalence of some of the clinical signs in individuals diagnosed with TSC.

The frequency of signs in children with TSC, grouped by age TSC-Frequency-Signs-Childhood.png
The frequency of signs in children with TSC, grouped by age

Genetics

TSC is inherited in an autosomal dominant fashion. Autosomal dominant - en.svg
TSC is inherited in an autosomal dominant fashion.

TSC is a genetic disorder with an autosomal dominant pattern of inheritance, variable expressivity, and incomplete penetrance. [12] [16] Two-thirds of TSC cases result from sporadic genetic mutations, not inheritance, but their offspring may inherit it from them. Current genetic tests have difficulty locating the mutation in roughly 20% of individuals diagnosed with the disease. So far, it has been mapped to two genetic loci, TSC1 and TSC2 . [17]

TSC1 encodes for the protein hamartin, is located on chromosome 9 q34, and was discovered in 1997. [18] TSC2 encodes for the protein tuberin, is located on chromosome 16 p13.3, and was discovered in 1993. [19] TSC2 is contiguous with PKD1, the gene involved in one form of polycystic kidney disease (PKD). Gross deletions affecting both genes may account for the 2% of individuals with TSC who also develop polycystic kidney disease in childhood. [20] TSC2 has been associated with a more severe form of TSC. [21] However, the difference is subtle and cannot be used to identify the mutation clinically. Estimates of the proportion of TSC caused by TSC2 range from 55% to 90%. [3]

TSC1 and TSC2 are both tumor suppressor genes that function according to Knudson's "two hit" hypothesis. That is, a second random mutation must occur before a tumor can develop. This explains why, despite its high penetrance, TSC has wide expressivity.[ citation needed ]

Hamartin
Identifiers
Symbol TSC1
NCBI gene 7248
HGNC 12362
OMIM 605284
RefSeq NM_000368
UniProt Q92574
Other data
Locus Chr. 9 q34
Search for
Structures Swiss-model
Domains InterPro
Tuberin
Identifiers
Symbol TSC2
NCBI gene 7249
HGNC 12363
OMIM 191092
RefSeq NM_000548
UniProt P49815
Other data
Locus Chr. 16 p13.3
Search for
Structures Swiss-model
Domains InterPro

Pathophysiology

Hamartin and tuberin function as a complex which is involved in the control of cell growth and cell division. The complex appears to interact with RHEB GTPase, thus sequestering it from activating mTOR signalling, part of the growth factor (insulin) signalling pathway. Thus, mutations at the TSC1 and TSC2 loci result in a loss of control of cell growth and cell division, and therefore a predisposition to forming tumors. TSC affects tissues from different germ layers. Cutaneous and visceral lesions may occur, including angiofibroma, cardiac rhabdomyomas, and renal angiomyolipomas. The central nervous system lesions seen in this disorder include hamartomas of the cortex, hamartomas of the ventricular walls, and subependymal giant cell tumors, which typically develop in the vicinity of the foramina of Monro.[ citation needed ]

Molecular genetic studies have defined at least two loci for TSC. In TSC1, the abnormality is localized on chromosome 9q34, but the nature of the gene protein, called hamartin, remains unclear. No missense mutations occur in TSC1. In TSC2, the gene abnormalities are on chromosome 16p13. This gene encodes tuberin, a guanosine triphosphatase–activating protein. The specific function of this protein is unknown. In TSC2, all types of mutations have been reported; new mutations occur frequently. Few differences have yet been observed in the clinical phenotypes of patients with mutation of one gene or the other.[ citation needed ]

Cells from individuals with pathogenic mutations in the TSC2 gene display abnormal accumulation of glycogen that is associated with depletion of lysosomes and autophagic impairment. The defective degradation of glycogen by the autophagy-lysosome pathway is, at least in part, independent of impaired regulation of mTORC1 and is restored, in cultured cells, by the combined use of PKB/Akt and mTORC1 pharmacological inhibitors. [22]

Diagnosis

Tuberous sclerosis complex is diagnosed with clinical and genetic tests. There are many different mutations in the TSC1 and TSC2 genes that have been identified in individuals with TSC. A pathogenic mutation in the gene prevents the proteins from being made or inactivates the proteins. If such a pathogenic mutation is found then this alone is sufficient to diagnose TSC. However, some mutations are less clear in their effect, and so not sufficient alone for diagnosis. Between 1 in 10 and 1 in 4 of individuals with TSC have no mutation that can be identified. Once a particular mutation is identified in someone with TSC, this mutation can be used to make confident diagnoses in other family members. [11]

For clinical diagnosis, there isn't one sign that is unique (pathognomonic) to TSC, nor are all signs seen in all individuals. Therefore, several signs are considered together, classed as either major or minor features. An individual with two major features, or one major feature and at least two minor features can be given a definite diagnosis of TSC. If only one major feature or at least two minor features are present, the diagnosis is only regarded as possibly TSC. [11]

Diagnostic Criteria for Tuberous Sclerosis Complex [11]
Major Features
LocationSignOnset [23] Note
1SkinHypomelanotic macules Infant – childAt least three, at least 5 mm in diameter.
2HeadFacial angiofibromas or fibrous cephalic plaqueInfant – adultAt least three angiofibromas
3Fingers and toesUngual fibroma Adolescent – adultAt least two
4SkinShagreen patch (connective tissue nevus)Child
5EyesMultiple retinal nodular hamartomas Infant
6Brain Cortical dysplasiasFetus(includes tubers and cerebral white matter radial migration lines)
7Brain Subependymal nodule Child – adolescent
8Brain Subependymal giant cell astrocytoma Child – adolescent
9HeartCardiac rhabdomyoma Fetus
10Lungs Lymphangioleiomyomatosis Adolescent – adult
11KidneysRenal angiomyolipoma Child – adultAt least two. Together, 10 and 11 count as one major feature.
Minor Features
LocationSignNote
1Skin"Confetti" skin lesions
2TeethDental enamel pitsAt least three
3GumsIntraoral fibromasAt least two
4EyesRetinal achromic patch
5KidneysMultiple renal cysts
6Liver, spleen and other organsNonrenal hamartoma

TSC can be first diagnosed at any stage of life. Prenatal diagnosis is possible by chance if heart tumours are discovered during routine ultrasound. In infancy, epilepsy, particularly infantile spasms, or developmental delay may lead to neurological tests. The white patches on the skin may also first become noticed. In childhood, behavioural problems and autism spectrum disorder may provoke a diagnosis. During adolescence, the skin problems appear. In adulthood, kidney and lung problems may develop. An individual may also be diagnosed at any time as a result of genetic testing of family members of another affected person. [24]

Management

Tuberous sclerosis complex affects multiple organ systems so a multidisciplinary team of medical professionals is required.[ citation needed ]

In suspected or newly diagnosed TSC, the following tests and procedures are recommended by 2012 International Tuberous Sclerosis Complex Consensus Conference. [25]

The various symptoms and complications from TSC may appear throughout life, requiring continued surveillance and adjustment to treatments. The following ongoing tests and procedures are recommended by 2012 International Tuberous Sclerosis Complex Consensus Conference. [25]

The mTOR inhibitor everolimus was approved in the US for treatment of TSC-related tumors in the brain (subependymal giant cell astrocytoma) in 2010 and in the kidneys (renal angiomyolipoma) in 2012. [26] [27]   Oral everolimus (rapalog) reduces tumour size, is effective in terms of response to skin lesions and does not increase the risk of adverse events. [28] Everolimus also showed evidence of effectiveness at treating epilepsy in some people with TSC. [29] [30] In 2017, the European Commission approved everolimus for treatment of refractory partial-onset seizures associated with TSC. [31]

Neurosurgical intervention may reduce the severity and frequency of seizures in TSC patients. [32] [33] Embolization and other surgical interventions can be used to treat renal angiomyolipoma with acute hemorrhage. Surgical treatments for symptoms of lymphangioleiomyomatosis (LAM) in adult TSC patients include pleurodesis to prevent pneumothorax and lung transplantation in the case of irreversible lung failure. [25]

Other treatments that have been used to treat TSC manifestations and symptoms include a ketogenic diet for intractable epilepsy and pulmonary rehabilitation for LAM. [34] Facial angiofibromas can be reduced with laser treatment and the effectiveness of mTOR inhibitor topical treatment is being investigated. Laser therapy is painful, requires anaesthesia, and has risks of scarring and dyspigmentation. [35]

Prognosis

The prognosis for individuals with TSC depends on the severity of symptoms, which range from mild skin abnormalities to varying degrees of learning disabilities and epilepsy to severe intellectual disability, uncontrollable seizures, and kidney failure. Those individuals with mild symptoms generally do well and live long, productive lives, while individuals with the more severe form may have serious disabilities. However, with appropriate medical care, most individuals with the disorder can look forward to normal life expectancy. [4]

A study of 30 TSC patients in Egypt found, "...earlier age of seizures commencement (<6 months) is associated with poor seizure outcome and poor intellectual capabilities. Infantile spasms and severely epileptogenic EEG patterns are related to the poor seizure outcome, poor intellectual capabilities and autistic behavior. Higher tubers numbers is associated with poor seizure outcome and autistic behavior. Left-sided tuber burden is associated with poor intellect, while frontal location is more encountered in ASD [ autism spectrum disorders]. So, close follow up for the mental development and early control of seizures are recommended in a trial to reduce the risk factors of poor outcome. Also early diagnosis of autism will allow for earlier treatment and the potential for better outcome for children with TSC." [36]

Leading causes of death include renal disease, brain tumour, lymphangioleiomyomatosis of the lung, and status epilepticus or bronchopneumonia in those with severe intellectual disability. [37] Cardiac failure due to rhabdomyomas is a risk in the fetus or neonate but is rarely a problem subsequently. Kidney complications such as angiomyolipoma and cysts are common and more frequent in females than males and in TSC2 than TSC1. Renal cell carcinoma is uncommon. Lymphangioleiomyomatosis is only a risk for females with angiomyolipomas. [38] In the brain, the subependymal nodules occasionally degenerate to subependymal giant cell astrocytomas. These may block the circulation of cerebrospinal fluid around the brain, leading to hydrocephalus.[ citation needed ]

Detection of the disease should be followed by genetic counselling. It is also important to realize that though the disease does not have a cure, symptoms can be treated symptomatically. Hence, awareness regarding different organ manifestations of TSC is important. [39]

Epidemiology

TSC occurs in all races and ethnic groups, and in both sexes. The live-birth prevalence is estimated to be between 10 and 16 cases per 100,000. A 1998 study [2] estimated total population prevalence between about 7 and 12 cases per 100,000, with more than half of these cases undetected. Prior to the invention of CT scanning to identify the nodules and tubers in the brain, the prevalence was thought to be much lower, and the disease associated with those people diagnosed clinically with learning disability, seizures and facial angiofibroma. Whilst still regarded as a rare disease, TSC is common when compared to many other genetic diseases, with at least 1 million individuals affected worldwide. [15]

History

Desire-Magloire Bourneville Desire-Magloire Bourneville.jpg
Désiré-Magloire Bourneville

TSC first came to medical attention when dermatologists described the distinctive facial rash (1835 and 1850). A more complete case was presented by von Recklinghausen (1862), who identified heart and brain tumours in a newborn who had only briefly lived. However, Bourneville (1880) is credited with having first characterized the disease, coining the name "tuberous sclerosis", thus earning the eponym Bourneville's disease. The neurologist Vogt (1908) established a diagnostic triad of epilepsy, idiocy, and adenoma sebaceum (an obsolete term for facial angiofibroma). [40]

Symptoms were periodically added to the clinical picture. The disease as presently understood was first fully described by Gomez (1979). The invention of medical ultrasound, CT and MRI has allowed physicians to examine the internal organs of live patients and greatly improved diagnostic ability.[ citation needed ]

In 2002, treatment with rapamycin was found to be effective at shrinking tumours in animals. This has led to human trials of rapamycin as a drug to treat several of the tumors associated with TSC. [41]

See also

Related Research Articles

<span class="mw-page-title-main">Sirolimus</span> Pharmaceutical drug

Sirolimus, also known as rapamycin and sold under the brand name Rapamune among others, is a macrolide compound that is used to coat coronary stents, prevent organ transplant rejection, treat a rare lung disease called lymphangioleiomyomatosis, and treat perivascular epithelioid cell tumor (PEComa). It has immunosuppressant functions in humans and is especially useful in preventing the rejection of kidney transplants. It is a mechanistic target of rapamycin (mTOR) kinase inhibitor that reduces the sensitivity of T cells and B cells to interleukin-2 (IL-2), inhibiting their activity.

<span class="mw-page-title-main">Everolimus</span> Chemical compound

Everolimus, sold under the brand name Afinitor among others, is a medication used as an immunosuppressant to prevent rejection of organ transplants and as a targeted therapy in the treatment of renal cell cancer and other tumours.

<span class="mw-page-title-main">Rhabdomyoma</span> Medical condition

A rhabdomyoma is a benign tumor of striated muscle. Rhabdomyomas may be either cardiac or extracardiac. Extracardiac forms of rhabdomyoma are sub-classified into three distinct types: adult type, fetal type, and genital type.

<span class="mw-page-title-main">Benign tumor</span> Mass of cells which cannot spread throughout the body

A benign tumor is a mass of cells (tumor) that does not invade neighboring tissue or metastasize. Compared to malignant (cancerous) tumors, benign tumors generally have a slower growth rate. Benign tumors have relatively well differentiated cells. They are often surrounded by an outer surface or stay contained within the epithelium. Common examples of benign tumors include moles and uterine fibroids.

<span class="mw-page-title-main">Birt–Hogg–Dubé syndrome</span> Rare autosomal dominant cancer syndrome

Birt–Hogg–Dubé syndrome (BHD), also Hornstein–Birt–Hogg–Dubé syndrome, Hornstein–Knickenberg syndrome, and fibrofolliculomas with trichodiscomas and acrochordons is a human, adult onset, autosomal dominant genetic disorder caused by a mutation in the folliculin (FLCN) gene. It can cause susceptibility to kidney cancer, renal and pulmonary cysts, and noncancerous tumors of the hair follicles, called fibrofolliculomas. The symptoms seen in each family are unique, and can include any combination of the three symptoms. Fibrofolliculomas are the most common manifestation, found on the face and upper trunk in over 80% of people with BHD over the age of 40. Pulmonary cysts are equally common (84%) and 24% of people with BHD eventually experience a collapsed lung. Kidney tumors, both cancerous and benign, occur in 14–34% of people with BHD; the associated kidney cancers are often rare hybrid tumors.

<span class="mw-page-title-main">Lymphangioleiomyomatosis</span> Medical condition

Lymphangioleiomyomatosis (LAM) is a rare, progressive and systemic disease that typically results in cystic lung destruction. It predominantly affects women, especially during childbearing years. The term sporadic LAM is used for patients with LAM not associated with tuberous sclerosis complex (TSC), while TSC-LAM refers to LAM that is associated with TSC.

<span class="mw-page-title-main">Hamartoma</span> Tumour-like overgrowth due to a systemic genetic condition

A hamartoma is a mostly benign, local malformation of cells that resembles a neoplasm of local tissue but is usually due to an overgrowth of multiple aberrant cells, with a basis in a systemic genetic condition, rather than a growth descended from a single mutated cell (monoclonality), as would typically define a benign neoplasm/tumor. Despite this, many hamartomas are found to have clonal chromosomal aberrations that are acquired through somatic mutations, and on this basis the term hamartoma is sometimes considered synonymous with neoplasm. Hamartomas are by definition benign, slow-growing or self-limiting, though the underlying condition may still predispose the individual towards malignancies.

Phakomatoses, also known as 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.

Tuberous sclerosis complex (TSC) tumor suppressors form the TSC1-TSC2 molecular complex. Under poor growth conditions the TSC1-TSC2 complex limits cell growth. A key promoter of cell growth, mTORC1, is inhibited by the tuberous sclerosis complex. Insulin activates mTORC1 and causes dissociation of TSC from the surface of lysosomes.

<span class="mw-page-title-main">Angiomyolipoma</span> Medical condition

Angiomyolipomas are the most common benign tumour of the kidney. Although regarded as benign, angiomyolipomas may grow such that kidney function is impaired or the blood vessels may dilate and burst, leading to bleeding.

<span class="mw-page-title-main">Timeline of tuberous sclerosis</span>

The history of tuberous sclerosis (TSC) research spans less than 200 years. TSC is a rare, multi-system genetic disease that can cause benign tumours to grow on the brain or other vital organs such as the kidneys, heart, eyes, lungs, and skin. A combination of symptoms may include seizures, developmental delay, behavioural problems and skin abnormalities, as well as lung and kidney disease. TSC is caused by mutations on either of two genes, TSC1 and TSC2, which encode for the proteins hamartin and tuberin respectively. These proteins act as tumour growth suppressors and regulate cell proliferation and differentiation. Originally regarded as a rare pathological curiosity, it is now an important focus of research into tumour formation and suppression.

<span class="mw-page-title-main">TSC1</span>

Tuberous sclerosis 1 (TSC1), also known as hamartin, is a protein that in humans is encoded by the TSC1 gene.

<span class="mw-page-title-main">TSC2</span> Mammalian protein found in Homo sapiens

Tuberous sclerosis complex 2 (TSC2), also known as tuberin, is a protein that in humans is encoded by the TSC2 gene.

<span class="mw-page-title-main">Angiofibroma</span> Medical condition

Angiofibroma (AGF) is a descriptive term for a wide range of benign skin or mucous membrane lesions in which individuals have:

  1. benign papules, i.e. pinhead-sized elevations that lack visible evidence of containing fluid;
  2. nodules, i.e. small firm lumps usually >0.1 cm in diameter; and/or
  3. tumors, i.e. masses often regarded as ~0.8 cm or larger.

Kun-Liang Guan, is a Chinese and American biochemist. He won the MacArthur Award in 1998.

<span class="mw-page-title-main">Perivascular epithelioid cell tumour</span> Medical condition

Perivascular epithelioid cell tumour, also known as PEComa or PEC tumour, is a family of mesenchymal tumours consisting of perivascular epithelioid cells (PECs). These are rare tumours that can occur in any part of the human body.

<span class="mw-page-title-main">Koenen's tumor</span> Medical condition

Koenen's tumor (KT), also commonly termed periungual angiofibroma, is a subtype of the angiofibromas. Angiofibromas are benign papule, nodule, and/or tumor lesions that are separated into various subtypes based primarily on the characteristic locations of their lesions. KTs are angiofibromas that develop in and under the toenails and/or fingernails. KTs were once considered as the same as another subtype of the angiofibromas viz., acral angiofibromas. While the literature may still sometimes regard KTs as acral angiofibromas, acral angiofibromas are characteristically located in areas close to but not in the toenails and fingernails as well as in the soles of the feet and palms of the hands. KTs are here regarded as distinct from acral angiofibromas.

Tuberous sclerosis proteins 1 and 2, also known as TSC1 (hamartin) and TSC2 (tuberin), form a protein-complex. The encoding two genes are TSC1 and TSC2. The complex is known as a tumor suppressor. Mutations in these genes can cause tuberous sclerosis complex. Depending on the grade of the disease, intellectual disability, epilepsy and tumors of the skin, retina, heart, kidney and the central nervous system can be symptoms.

<span class="mw-page-title-main">Subependymal giant cell astrocytoma</span> Medical condition

Subependymal giant cell astrocytoma is a low-grade astrocytic brain tumor (astrocytoma) that arises within the ventricles of the brain. It is most commonly associated with tuberous sclerosis complex (TSC). Although it is a low-grade tumor, its location can potentially obstruct the ventricles and lead to hydrocephalus.

<span class="mw-page-title-main">Multifocal micronodular pneumocyte hyperplasia</span>

Multifocal micronodular pneumocyte hyperplasia (MMPH) is a subtype of pneumocytic hyperplasia.

References

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  3. 1 2 Rendtorff ND, Bjerregaard B, Frödin M, Kjaergaard S, Hove H, Skovby F, Brøndum-Nielsen K, Schwartz M (October 2005). "Analysis of 65 tuberous sclerosis complex (TSC) patients by TSC2 DGGE, TSC1/TSC2 MLPA, and TSC1 long-range PCR sequencing, and report of 28 novel mutations". Human Mutation. 26 (4): 374–83. doi: 10.1002/humu.20227 . PMID   16114042. S2CID   10571695.
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