Answer and Discussion of Quiz Set: N-019
4. Which of the following genetic alteration is often mutated in diffuse astrocytoma (WHO grade II)?
A. BRAF-KIAA1549 fusion
B. Mutation of isocitrate dehydrogenase (IDH) 1 and 2
C. Deletion of chromosome 1p and 19q
D. Deletion or mutation of hSNF5/INI1
E. Mutation of PTEN/MMAC1 gene on chromosome 10q23
Answer and Discussion: The answer is (B). The correlation of these genetic changes and brain tumors are as follow:
|
Gene |
CNS tumors |
|
BRAF-KIAA1549 fusion |
In pilocytic astrocytoma |
|
IDH 1/2 |
n infiltrating astrocytic and oligodendroglial tumors (WHO grade II and III) but uncommon in glioblastoma ilocytic astrocytoma |
|
1p and 19q Deletion |
In oligodendroglial tumors |
|
hSNF5/INI1 |
In atypical rhabdoid/teratoid tumor |
|
PTEN/MMAC1 gene |
In dysplastic gangliocytoma of the cerebellum (Lhermitte-Duclos disease), meningioima, and, medulloblastoma. Associated with Cowden syndrome |
Positive for BRAF-KIAA1549 fusion and negative for IDH 1/2 mutation is a good way to confirm pilocytic astrocytomas.