Neurofibromatosis

Question 1

What is neurofibromatosis?

Answer 1

A genetic condition that causes benign nerve tumours (neuromas) to form - causing neurological and structural problems.
There are two types - type 1 is more common.

Question 2

What is the genetics behind neurofibromatosis type 1?

Answer 2

• mutation on chromosome 7
• coding for a tumour supressor protein called neurofibromin
• autosomal dominant inheritance

Question 3

What is the inheritance pattern for neurofibromatosis type 1?

Answer 3

Autosomal dominant

Question 4

What is the diagnostic criteria for neurofibromatosis type 1?

Answer 4

Must meet at least 2 of the 7 features.
Mneumonia = CRABBING

C - cafe-au-lai spots (6 or more >5mm in kids or >15mm in adults)
R - relative with NF1
A - axillary or inguinal freckles
BB - bony dysplasia - e.g. bowing of long bone, scoliosis
I - Iris hamartoma (Lisch nodules) - 2 or more yellow/ brown dots on the iris
N - neurofibromas (2 or more)
G - glioma of the optic nerve

Question 5

Wha are some of the complications of neurofibromatosis type 1?

Answer 5

• migranes
• seizures
• learning and behavioural difficulties
• renal artery stenosis –> hypertension
• vision loss - secondary to optic gliomas
• lots of associated tumours –> brain, GI stromal, spinal cord, breast
• leukaemia
  + others

Question 6

What are the genetics behind neurofibromatosis type 2?

Answer 6

• gene on chromosome 22
• for tumour supressor protein merlin
• mutations in this lead to schwannoma development
• autosomal dominant inheritance

Question 7

What is the mode of inheritance of neurofibromatosis type 2?

Answer 7

Autosomal dominant

Question 8

How does neurofibromatosis type 2 typically present?

Answer 8

Most commonly acoustic neuromas (vestibular schwannomas)
- hearing loss, tinnitus, balance problems
- often bilateral
Can also cause meningiomas in the brain and spinal cord - causing symptoms relevant to its location