Multiple Endocrine Neoplasia, Type IIB
Patient Information
Characteristics
Background and History
This is an inherited disorder in which tumors form in nerves and certain glands in various parts of the body. There are several forms of the disease but a single gene mutation seems to be responsible.
Clinical Correlations
This disease can have its onset in early childhood. The most obvious signs of this disease (MEN 2) are thickened lips and eyelids with small tags or lumps protruding. The tongue and other tissues of the eye and mouth may also be involved. The benign nerve tumors may cause serious dysfunction of the colon and esophagus. Malignant tumors of the thyroid gland can be life threatening. Tumors of the adrenal gland (pheochromocytomas) also are often present. The facial features are distinctive and many patients are tall with scoliosis, a highly arched palate, and inward turning of the feet. Brown spots often appear on the trunk and the hands and feet may have an excess of pigmentation.
Genetics
Inheritance
This is an autosomal dominant disorder in which affected parents can expect that half of their children will have the same disease. About half of patients with this disorder do not have a family history of it and it is presumed that new mutations are responsible. The same genetic mutation is responsible for both the familial and sporadic cases however.
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
Cancer of the thyroid gland is the most serious feature of MEN2. There is good evidence that early treatment of the thyroid cancer can increase longevity. Pediatricians, internists, and endocrinologists can make the diagnosis and surgical treatment of lesions may be indicated.
Web Resources
Printer Friendly Version: Ctrl/Cmd+P