V. Familial Tumor Syndromes
This group of inherited diseases is characterized by the development of hamartomas (proliferations of normal cellular elements without progressive growth) and tumors throughout the body with particular involvement of the nervous system. Seizure disorders or mental retardation may be associated. The pattern of inheritance is variable. Many of the disorders are autosomal dominant and have been linked to tumor suppressor genes.
A. Neurofibromatosis Type 1 (NF1)
This autosomal dominant disorder is one of the more common genetic disorders. Characteristic nervous system lesions include neurofibromas and gliomas of the optic nerve. The gene, which encodes a protein termed neurofibromin, is a tumor suppressor gene.
B. Neurofibromatosis Type 2 (NF2)
In this autosomal dominant disorder, patients develop a range of tumors, including bilateral acoustic schwannomas and multiple meningiomas. The NF2 gene encodes a protein called merlin.
C. Tuberous sclerosis
Tuberous sclerosis is an autotomal dominant syndrome characterized by the development of hamartomas and benign neoplasms involving the brain and other tissues. Several distinct genetic loci have been identified at which mutations can cause tuberous sclerosis.