**Neurofibromatosis Type 1 (NF1)**

**Overview:**
Neurofibromatosis type 1, often abbreviated as NF1, is one of the most common genetic disorders affecting the nervous system. It's characterized by the growth of tumors along nerves, which can affect nearly any organ system in the body. NF1 is an autosomal dominant condition, meaning only one copy of the altered gene is needed for the disease to manifest, though in about half of cases, it arises from a new mutation rather than being inherited.

**Genetics:**
- **Gene Involved**: NF1 gene located on chromosome 17.
- **Function**: The NF1 gene produces a protein called neurofibromin, which regulates cell growth. Mutations in this gene lead to reduced or nonfunctional neurofibromin, allowing cells to grow uncontrolled.

**Symptoms and Features:**
- **Café-au-lait Spots**: Light brown, flat spots on the skin, usually present at birth or appearing in early childhood.
- **Neurofibromas**: Benign tumors that can grow anywhere on or in the body, including under the skin, along nerves, or in the brain and spinal cord.
- **Freckling**: In the armpits or groin area.
- **Lisch Nodules**: Hamartomas in the iris of the eye.
- **Skeletal Abnormalities**: Scoliosis, bone deformities, or thinning of long bones.
- **Optic Gliomas**: Tumors that can affect vision, occurring in the optic pathway.
- **Learning Disabilities**: Cognitive issues, including ADHD or learning disabilities, can be more common.
- **Hypertension**: Due to vascular issues like renal artery stenosis.

**Diagnosis:**
- Clinical diagnosis based on the presence of two or more of the following:
  - Six or more café-au-lait spots of more than 5 mm in greatest diameter in prepubertal individuals and over 15 mm in postpubertal individuals.
  - Two or more neurofibromas of any type or one plexiform neurofibroma.
  - Freckling in the axillary or inguinal regions.
  - Optic glioma.
  - Two or more Lisch nodules.
  - A distinctive osseous lesion like sphenoid dysplasia or thinning of the cortex of long bones.
  - A first-degree relative (parent, sibling, or child) with NF1.

**Management and Treatment:**
- **Regular Monitoring**: For tumor growth, especially in the brain, spine, or eyes.
- **Surgical Removal**: Of symptomatic or cosmetically concerning neurofibromas.
- **Medical Management**: For associated conditions like hypertension, learning disabilities, or skeletal issues.
- **Genetic Counseling**: For family planning.