Akademik

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Under this heading are grouped two distinct hereditary disorders, formerly labeled peripheral and central n., but now entitled n. type 1 and type 2. Type 1 (peripheral) n., [MIM*162200] by far the most common of the two types, is characterized clinically by the combination of patches of hyperpigmentation and cutaneous and subcutaneous tumors. The hyperpigmented skin areas, present from birth and found anywhere on the body surface, can vary markedly in size and color—the dark brown ones are called café-au-lait spots. The multiple cutaneous and subcutaneous tumors, nerve sheath neoplasms, called neurofibromas, can develop anywhere along the peripheral nerve fibers, from the roots distally. Neurofibromas can become quite large, causing a major disfigurement, eroding bone, and compressing various peripheral nerve structures; a small hamartoma (Lisch nodule) can be found in the iris of almost all patients. Type 1 n., also called von Recklinghausen disease, has autosomal dominant inheritance, with the gene locus on chromosome 17q11, and is caused by mutation in the NF1 gene that encodes neurofibromin. Type 2 (central) n. [MIM*101000] has few cutaneous manifestations, and consists primarily of bilateral (less often, unilateral) acoustic neuromas, causing deafness, often accompanied by other intracranial and paraspinal neoplasms, such as meningiomas and gliomas. Type 2 n. also has autosomal dominant inheritance, but the gene locus is on 22q11, caused by mutation in the NF2 gene encoding the product merlin. SYN: elephant man's disease (2).

- abortive n. SYN: incomplete n..

- central type n. type 2 n.. See n..

- incomplete n. multiple neurofibromas with minimal manifestations, perhaps limited to café-au-lait spots; individuals with minimal lesions may have offspring with severe involvement. SYN: abortive n..

neu·ro·fi·bro·ma·to·sis -fī-.brō-mə-'tō-səs n, pl -to·ses -.sēz a disorder inherited as an autosomal dominant trait and characterized by brown spots on the skin, neurofibromas of peripheral nerves, and deformities of subcutaneous tissues and bone abbr. NF called also Recklinghausen's disease, von Recklinghausen's disease

a congenital disease, inherited as a dominant characteristic, that is typified by numerous benign tumours growing from the fibrous coverings of nerves (see neurofibroma). Tumours may occur in the spinal canal, where they may press on the spinal cord. The tumours can be felt beneath the skin along the course of the nerves; they sometimes (but rarely) become malignant, giving rise to neurofibrosarcomas. Pigmented patches on the skin (see café au lait spots) are commonly found. Neurofibromatosis is sometimes associated with fibrous dysplasia and occasionally with the adrenal tumour phaeochromocytoma, acoustic neuroma, glioma, or meningioma.