Neurofibromatosis Type 1

WHAT IS IT? 

Neurofibromatosis type 1 (NF1): Neurocutaneous autosomal dominant genetic disorder with highly variable manifestations. This is also called von Recklinghausen disease. Caused by a mutation in the NF1 gene that codes for a Ras GTPase activating protein (neurofibromin). This gene is a tumor suppressor!

WHY IS IT A PROBLEM?

The loss of this tumor suppressor gene leads to the formation of neurofibromas in the skin derived from neural crest cells (uncontrolled cellular proliferation)

WHAT MAKES US SUSPECT IT?

Risk factors:  family history (race, ethnicity and gender are NOT risk factors).

Cafe au lait macules: patients present with these very commonly for this condition.

Cafe au last spots in a patient with NFN1 (source)
Cafe au last spots in a patient with NF1 (source)

Neurofibromas: Short, sessile, or pedunculated lesions that vary in size. They are commonly multiple and distributed throughout the body.  A hallmark of this disease.

Neurofibromas in a patient with NF1 (source)
Neurofibromas in a patient with NF1 (source)

Lish nodules: pigmented, asymptomatic hamartomas (focal malformation) of the iris.

Typical clincial presentation of multiple lish nodules (source)
Typical clincial presentation of multiple lish nodules (source)
HOW DO WE CONFIRM A DIAGNOSIS?

Diagnosis made clinically using National Institutes of Health (NIH) diagnostic criteria for neurofibromatosis type 1, comprised of ≥ 2 of following:

  •  neurofibromas
  • ≥ 6 cafe au lait macules/spots
  • freckling in axillary or inguinal areas
  • optic glioma
  • ≥ 2 Lisch nodules
  • distinctive osseous lesion which include sphenoid dysplasia or bowing of long bones with or without pseudoarthrosis
  • first degree relative with neurofibromatosis type 1 (diagnosed using above criteria)
HOW DO WE RULE OTHER DIAGNOSES OUT?

Mutation analyses is rarely indicated, but can be used to confirm diagnosis definitely by identifying casual mutation in gene NF1

HOW DO WE TREAT IT? 

Depending on the number or localization of tumors, treatment options include: surgery, chemotherapy, imatnib, and sometimes radiation therapy.

HOW WELL DO THE PATIENTS DO?

Life expectancy in patients with neurofibromatosis type 1 may be 8-20 years shorter than general population

WAS THERE A WAY TO PREVENT IT? 

No this is a genetic condition.

WHAT ELSE ARE WE WORRIED ABOUT? 

Pheochromocytoma (tumor of chromatin cells) is associated with Neurofibromatosis type 1

OTHER HY FACTS?

Chromosme 17 houses the NF1 gene

ARCHIVE OF STANDARDIZED EXAM QUESTIONS 

This archive compiles standardized exam questions that relate to this topic.

FURTHER READING

DynaMed

UpToDate

Page Updated: 02.04.2016