Clinical features: Tuberous sclerosis is a multi-system disorder which vary greatly in the degree and severity of its signs and symptoms even within a family. It is important to take a detailed family history and examine relatives at risk- particularly before assuming someone is the only person affected in the family. Diagnostic criteria have been established and should always be used when assessing individuals. A person has definite TSC if he or she has two major features, or one major feature plus two minor features, probable TSC if he or she has one major feature plus one minor feature, and possible TSC if he or she has one major feature or two or more minor features. The major features are:
Identifying affected individuals enables monitoring for early detection of problems associated with TSC, thus leading to earlier treatment and better outcomes. It is also recommended that parents of an individual with TSC are evaluated for signs of the disorder, including renal ultrasonography and cranial CT scanning.
Incidence: The incidence of TSC is now thought to be as high as one in 5,800 live births.
Inheritance: Autosomal dominant, two-thirds of affected individuals have TSC as the result of a new mutation.
Gene: Two genes are known to cause tuberous sclerosis, TSC1 (hamartin) on chromosome 9 and TSC2 (tuberin) on chromosome 16.
DNA testing: Yes, is available but complicated and a mutation is detected by current technology approximately in 70% of cases.
Prenatal diagnosis: May be possible by DNA testing (gene tracking or mutation analysis) if appropriate studies have been carried out on the family. High-resolution ultrasound examination or fetal MRI may be helpful in the assessment of fetuses known to be at 50% risk of tuberous sclerosis, but their usefulness has not been evaluated. If a family is considering prenatal diagnosis, referral should be made to the local clinical genetics service prior to a pregnancy. This ensures family members are offered appropriate advice and investigations, to confirm whether or not prenatal diagnosis is possible.
Head of Development and Support Services
Tuberous Sclerosis Association
PO Box 13938 Birmingham B45 5BF
Telephone 05602 420809 (Tues-Friday 0800-1500)