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Questions and Answers
What is the estimated incidence of Neurofibromatosis 1 (NF1) in the general population?
What percentage of patients with NF1 have de novo mutations?
What is the approximate percentage of de novo mutations in NF1 that are paternal in origin?
What is the approximate size of the NF1 gene?
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What is the primary function of neurofibromin, the protein encoded by the NF1 gene?
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What is the estimated number of mutations in the NF1 gene that have been identified?
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What is the estimated percentage of mutations in the NF1 gene that cause protein truncation?
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What percentage of individuals diagnosed with NF1 can be identified with a disease-causing mutation?
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What is the characteristic of NF1 that is probably caused by a combination of genetic, nongenetic, and stochastic factors?
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What type of mutations are more common in NF1 patients with neurodevelopmental difficulties?
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Study Notes
Disease Overview
- Neurofibromatosis 1 (NF1) is a panethnic autosomal dominant condition.
- Symptoms of NF1 are most frequently expressed in the skin, eye, skeleton, and nervous system.
Incidence and Genetics
- The incidence of NF1 is 1 in 3500 persons, making it one of the most common autosomal dominant genetic conditions.
- Approximately half of patients have de novo mutations.
- The mutation rate for the NF1 gene is approximately 1 mutation per 10,000 live births.
- Around 80% of de novo mutations are paternal in origin.
Gene Structure and Function
- The NF1 gene is large, with 350 kb and 60 exons.
- The gene encodes neurofibromin, a protein widely expressed in almost all tissues, but most abundantly in the brain, spinal cord, and peripheral nervous system.
- Neurofibromin regulates several intracellular processes, including the activation of Ras GTPase, controlling cellular proliferation and acting as a tumor suppressor.
Mutations and Clinical Manifestations
- Over 500 mutations in the NF1 gene have been identified, with most being unique to an individual family.
- The clinical manifestations result from a loss of function of the gene product.
- 80% of mutations cause protein truncation.
- A disease-causing mutation can be identified for more than 95% of individuals diagnosed with NF1.
Clinical Variability
- NF1 is characterized by extreme clinical variability, both between and within families.
- This variability is likely caused by a combination of genetic, nongenetic, and stochastic factors.
- No clear genotype-phenotype correlations have been recognized, although large deletions are more common in NF1 patients with neurodevelopmental difficulties.
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Description
This quiz covers the basics of Neurofibromatosis 1 (NF1), a genetic condition affecting the skin, eye, skeleton, and nervous system. Learn about the incidence, genetic mutations, and other key facts about NF1.
