Tumors of the central nervous system are the most frequent solid tumors in 
childhood. With 30-40% of this heterogenous group, low-grade astrocytomas 
represent the most common subtype. Neurofibromatosis type 1 (NF1) is strongly 
associated with the development of pilocytic astrocytoma (PA), frequently 
appearing as optic glioma. Neurofibromatosis 1 gene (NF1 ) fulfills the criteria 
of a tumor suppressor gene and is deleted or mutated heterozygously in patients 
with NF1. This suggests an involvement in the development of PA. To clarify 
whether silencing of NF1 by promoter methylation plays a role in PA and 
especially in optic glioma, the authors investigated the methylation status in 
30 PA, 6 of which had optic glioma. However, no methylation was found at the NF1 
promoter region in PA. To rule out that silencing of NF1 by promoter methylation 
is restricted to higher-grade astrocytomas, 15 pediatric WHO II degree and IV 
degree astrocytomas were analyzed: 12 astrocytomas II and 3 glioblastomas 
displayed no NF1 promoter methylation. The authors conclude that NF1 silencing 
by methylation plays no role in low-grade astrocytoma.