Neurofibromatosis

Question 1

What is it?

Answer 1

a genetic condition causing the formation of neuromas throughout the nervous system. They are benign however can cause neurological problems. NF type 1 is more common than type 2.

Question 2

pathophysiology of type 1?

Answer 2

• NF1 gene found on chromosome 17, important for the production of neurofibromin which is a tumour suppressor protein
• autosomal dominant inheritance

Question 3

Diagnosis of NF1?

Answer 3

must have AT LEAST 2/7 of following:

Cafe au lait spots: >5mm in children, >15mm in adults

Relative with NF1

Axillary or inguinal freckling

Bony dysphasia ie Bowing of long bones

Iris hamartomas ie Lysch nodules - must 2 or more

Neurofibromas - 2 or more

Glioma in optic nerve

Diagnosis based on clinical criteria alone, genetic testing can be done if there is uncertainty

Question 4

Complications?

Answer 4

• renal artery stenosis –> HT
• vision loss due to optic nerve glioma
• malignant peripheral nerve sheath tumours
• GI stromal tumour
• increased risk of malignancy in general

Question 5

Pathophysiology of NF2 and what is it associated with?

Answer 5

• NF2 gene is found on chromosome 22
• codes for protein merlin, a tumour suppressor protein especially important in Schwann cells
• therefore, mutation leads to formation of Schwannoma
• autosomal dominant inheritance
• association with acoustic neuroma