Tuberous Sclerosis 2
Patient Information
Characteristics
Background and History
Tuberous sclerosis consists of a complex of signs and symptoms with multiple, usually benign, tumors that occur throughout the body and in numerous organs, including the skin, eye, brain, kidneys and heart. The clinical effects of these vary widely based on the size and location of the tumors.
Clinical Correlations
The most obvious lesions are located in the skin where growths in the form of nodules appear between 3 and 5 years of age around the nose and in the eyelids in about 50% of patients. Pale patches known as ‘ashleaf’ patches are also commonly seen in the skin. Growths also may be found in the heart, and kidneys and gastrointestinal tract. Those in the brain along with other anomalies contribute to seizures, learning difficulties, behavioral problems, and sometimes mental retardation. Growths are also found in the retina and optic nerve of the eye. Those individuals more mildly affected may not be diagnosed until adulthood and often have few symptoms. In most cases the tumors are benign but cancer of the kidneys has been noted in a few patients.
Genetics
Inheritance
The majority of cases occur sporadically, that is, without a family history of the disease. However, familial cases do occur and in affected families the pattern is that of an autosomal dominant disorder with transmission from parent to child. In such families, the risk is 50% for recurrence for each child. Mutations in two genes have been associated with this disease.
Pedigree
Autosomal dominant
Autosomal dominant disorders require only one mutation for the disease to be expressed. Since an affected parent has two chromosomes, only one of which has the mutant gene, parents can expect that half (50%) of their children will receive that one and inherit the disease. It is common for individuals that inherit the mutation, however, to not have evidence of the disease (nonpenetrance).
Autosomal dominant inheritance leads to a vertical pattern of transmission
Diagnosis and Prognosis
The diagnosis requires a multidisciplinary approach, especially in persons with a mild form of the disease. Dermatologists, pediatricians, medical geneticists and other specialists often collaborate to make the diagnosis. The prognosis is highly variable depending upon the location and size of the tumors. Many patients are only mildly affected but others have more serious disease which may even be life-threatening. The tumors may need to be removed surgically but this is uncommon. Lifelong monitoring is important for early detection of malignancies, especially those of the kidney. No preventative treatment is available.
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