Neurofibromatosis Type 1

Question 1

NF1 Incidence

Answer 1

1/3500

Question 2

Common NF1 features

Answer 2

Multiple cafe au lait spots, axillary and inguinal freckling, multiple cutaneous neurofibromas, Lisch nodules, learning disabilities

Question 3

Less common NF1 features

Answer 3

Plexiform neurofibromas, optic nerve gliomas, other nervous system gliomas, malignant peripheral nerve sheath tumors, scoliosis, tibial dysplasia, vasculopathy

Question 4

NF1 clinical diagnostic criteria

Answer 4

(Need at least 2)
Six or more cafe au lait macules >5mm prepubertal, >15mm postpubertal
Two or more neurofibromas or one plexiform neurofibroma
Axillary or inguinal freckling
Optic glioma
Two or more Lisch nodules
A distinctive osseous lesion (sphenoid dysplasia or tibial pseudarthrosis)
First degree relative with NF1

Question 5

Age by which most patients with NF1 meet criteria

Answer 5

8

Question 6

When molecular testing is indicated for those thought to have NF1

Answer 6

When a patient doesn’t meet NIH criteria but appears to have NF1

Question 7

NF1 mode of inheritance

Answer 7

Autosomal dominant

Question 8

NF1 de novo rate

Answer 8

50%

Question 9

Number of NF1 mutations

Answer 9

500 (most unique to families, 80% truncating)

Question 10

Recurrence risk for sibs of a patient with apparently de novo NF1 mutation

Answer 10

Slightly greater than population risk (chance for germline mosaicism)

Question 11

Purpose of neurofibromin

Answer 11

Regulator of intracellular processes including activation Ras GTPase (to control cell proliferation)

Question 12

NF1 sequencing detection rate

Answer 12

90%

Question 13

NF1 del/dup detection rate

Answer 13

4-5%

Question 14

NF1 treatment/management

Answer 14

Surgical removal of plexiform neurofibromas, ophthalmology surveillance, monitor blood pressure, annual physicals