Neurology: Neurofibromatosis

Question 1

Neurofibromatosis type 1 is caused by…

Answer 1

A mutation in the neurofibromin-1 gene
It is autosomal dominant
Can occur de novo in 50% cases

Question 2

To make a diagnosis 2 or more of the following need to be present…

Answer 2

Six or more cafe au lait spots greater than 5mm in size before puberty, greater than 15mm after
More than 1 neurofibroma- firm nodular overgrowth of any nerve
Axillary freckling
Optic glioma
Lisch nodule
Bony lesions from sphenoid dysplasia - can cause eye protrusion
First degree relative with condition

Question 3

Is the expression of NF1 variable even within a family?

Answer 3

Yes

Question 4

Do the cafe au lait spots predispose to skin cancer?

Answer 4

No

Question 5

What are Lisch nodules?

Answer 5

Small brown mounds (hamartomas) on the iris

Question 6

What complications are associated with NF1

Answer 6

Mild learning disability common
Local effect of neurofibromas- nerve root compression 
Scoliosis
Cystic bone lesions 
HTN due to renal artery stenosis 
Epilepsy sometimes seen

Question 7

Is NF1 or NF2 more common?

Answer 7

NF1

Question 8

What is associated with NF2?

Answer 8

Bilateral acoustic neuromas = predominant feature
Cafe au lait spots fewer
Multiple inherited schwannomas, meningiomas, ependymomas

Question 9

Both NF1 and 2 are associated with …

Answer 9

The multiple endocrine neoplasia syndromes
Phaeochromocytoma
Pulmonary HTN
Renal artery stenosis with HTN