Tuberous sclerosis

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.

[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] 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.

[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.

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] About 90% of people with TSC develop a range of neurodevelopmental, behavioural, psychiatric, and psychosocial difficulties.

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.

[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.

[citation needed] 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.

[9] 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.

The following table shows the prevalence of some of the clinical signs in individuals diagnosed with TSC.TSC is a genetic disorder with an autosomal dominant pattern of inheritance, variable expressivity, and incomplete penetrance.

Gross deletions affecting both genes may account for the 2% of individuals with TSC who also develop polycystic kidney disease in childhood.

[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.

[24] 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.

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.

[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.

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.

"[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.

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.

A more complete case was presented by von Recklinghausen (1862), who identified heart and brain tumours in a newborn who had only briefly lived.

The neurologist Vogt (1908) established a diagnostic triad of epilepsy, idiocy, and adenoma sebaceum (an obsolete term for facial angiofibroma).

The invention of medical ultrasound, CT and MRI has allowed physicians to examine the internal organs of live patients and greatly improved diagnostic ability.

TSC in MRI
Computed tomography showing multiple angiomyolipomas of the kidney in a patient with lung lymphangioleiomyomatosis on CT: suspected TSC
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.
The frequency of signs in children with TSC, grouped by age [ 15 ]
TSC is inherited in an autosomal dominant fashion.