Neurofibromatosis
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Neurofibromatosis
Genetics
Population genetics
Mendelian genetics and punnett squares
Hardy-Weinberg equilibrium
Inheritance patterns
Independent assortment of genes and linkage
Evolution and natural selection
Genetic disorders
Down syndrome (Trisomy 21)
Edwards syndrome (Trisomy 18)
Patau syndrome (Trisomy 13)
Fragile X syndrome
Huntington disease
Myotonic dystrophy
Friedreich ataxia
Turner syndrome
Klinefelter syndrome
Prader-Willi syndrome
Angelman syndrome
Beckwith-Wiedemann syndrome
Cri du chat syndrome
Williams syndrome
Alagille syndrome (NORD)
Achondroplasia
Polycystic kidney disease
Familial adenomatous polyposis
Familial hypercholesterolemia
Hereditary spherocytosis
Huntington disease
Li-Fraumeni syndrome
Marfan syndrome
Multiple endocrine neoplasia
Myotonic dystrophy
Neurofibromatosis
Treacher Collins syndrome
Tuberous sclerosis
von Hippel-Lindau disease
Albinism
Polycystic kidney disease
Cystic fibrosis
Friedreich ataxia
Gaucher disease (NORD)
Glycogen storage disease type I
Glycogen storage disease type II (NORD)
Glycogen storage disease type III
Glycogen storage disease type IV
Glycogen storage disease type V
Hemochromatosis
Mucopolysaccharide storage disease type 1 (Hurler syndrome) (NORD)
Krabbe disease
Leukodystrophy
Niemann-Pick disease types A and B (NORD)
Niemann-Pick disease type C
Primary ciliary dyskinesia
Phenylketonuria (NORD)
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Tay-Sachs disease (NORD)
Alpha-thalassemia
Beta-thalassemia
Wilson disease
Fragile X syndrome
Alport syndrome
X-linked agammaglobulinemia
Fabry disease (NORD)
Glucose-6-phosphate dehydrogenase (G6PD) deficiency
Hemophilia
Mucopolysaccharide storage disease type 2 (Hunter syndrome) (NORD)
Lesch-Nyhan syndrome
Muscular dystrophy
Ornithine transcarbamylase deficiency
Wiskott-Aldrich syndrome
Mitochondrial myopathy
Autosomal trisomies: Pathology review
Muscular dystrophies and mitochondrial myopathies: Pathology review
Miscellaneous genetic disorders: Pathology review
Assessments
Neurofibromatosis
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External References
First Aid
2016
Café-au-lait spots
neurofibromatosis type 1 as cause p. 71, 495
Lisch nodules
neurofibromatosis type 1 as cause p. 71, 495
NF1 gene
neurofibromatosis type 1 and p. 71, 495
Optic gliomas
neurofibromatosis type 1 as cause p. 71, 630
neurofibromatosis type I as cause p. 495
Pheochromocytomas p. 320, 645
neurofibromatosis type 1 as cause p. 71, 495
External Links
Transcript
Contributors
Harry Delaney, MBChB
Gil McIntire
Tanner Marshall, MS
With neurofibromatoses, neuro refers to the nerves, fibro- refers to fibrous tissue, and -oma means growth, or tumor.
So neurofibromatosis refers to fibrous tumors originating from the nervous system.
The body’s central nervous system is made up of the brain and the spinal cord, which are surrounded by three protective layers called the meninges.
Part of the central nervous system are the cranial nerves, which originate in the brainstem and innervate the head and neck, and the spinal nerves, which originate in the spinal cord, and supply the rest of the body.
Each nerve is surrounded by a nerve sheath, which is produced by cells called fibroblasts.
Inside, each nerve there are several fascicles, and each fascicle, in turn, is made up of several axons.
The axons are the long projections of neurons, that carry the information as electrical signals running up and down their length.
Along the axon there are cells called Schwann cells, which produce a myelin cover for the axon.
The myelin helps electrical signals travel along the axon faster.
Now, neurofibromatoses are genetic diseases which cause non-cancerous growths to form in the body’s nerve tissue, and there are two types - type I and type II.
They’re caused by inheriting faulty copies of either the NF1 or NF2 gene, which are found on chromosomes 17 and 22, respectively.
Just remember, NF1 goes with chromosome 17 and NF2 goes with chromosome 22.
Both of these have an autosomal dominant inheritance pattern, so a child only needs one faulty copy from either parent to get the disease.
Normally, these are tumor suppressor genes, which means they stop cells from dividing uncontrollably.
So when there’s a mutation in the gene, it leads to uncontrolled growth of fibromas which are growths that have multiple cell types including neurons, Schwann cells, and other supporting connective tissue.
Summary
Neurofibromatosis is a genetic disorder characterized by fibrous tumors that affect the development and function of the nervous system. There are three known types of neurofibromatosis: neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), and schwannomatosis.
NF1 is due to a mutation in the NF1 gene on chromosome 17, and generally affects the skin and extremities. NF1 causes cutaneous neurofibromas (benign tumors that grow from the nerve sheath), caf-au-lait spots (flat patches with milky-coffee color), and Lisch nodules (small tan colored bumps). NF2 is caused by a mutation in the NF2 gene on chromosome 22, and is associated with bilateral acoustic neuromas that can cause tinnitus, and bilateral gradual loss of hearing. NF2 is also associated with multiple meningiomas in the brain and spinal cord.
Schwannomatosis is a rare form of neurofibromatosis, characterized by multiple schwannomas, pain, and numbness in the affected areas. Unlike NF2, schwannomatosis spare the vestibular nerve.
Sources
- "Robbins Basic Pathology" Elsevier (2017)
- "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
- "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
- "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
- "Neurofibromatosis" Orthopaedics and Trauma (2015)
- "Review Article : Molecular and Cellular Mechanisms Underlying the Cognitive Deficits Associated With Neurofibromatosis 1" Journal of Child Neurology (2002)
- "The Neurofibromatosis 2 Tumor Suppressor Gene Product, Merlin, Regulates Human Meningioma Cell Growth by Signaling through YAP" Neoplasia (2008)
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