Familial gliomas: cases in two pairs of brothers.

The majority of gliomas are sporadic in origin. Familial gliomas have been reported, though they are exceptionally rare. Several familial cancer syndromes are associated with autosomal dominant glioma risk, typically with incomplete penetrance. When two siblings are affected in the absence of a known dominantly inherited cancer syndrome, an autosomal recessive condition may be suspected (e.g. constitutional mismatch repair syndrome). We present two separate sets of siblings, one set with low grade gliomas, and the other with high grade gliomas. Histology for all tumors were either oligodendroglioma or had features of oligodendroglioma. Interestingly, there is a nearly identical histopathology and anatomical localization noted in these clinical presentations. For one family, genetic testing and family inquiry have resulted in no identifiable genetic pattern of disease. High-penetrance familial mutations and common low-penetrance susceptibility loci (e.g. single-nucleotide polymorphism (SNPs)) may contribute to familial glioma risk. We present two instances of familial glioma without an identifiable genetic cause. These cases implicate a potential heritable etiology for glioma families in which Mendelian disorders have not been identified. Further investigation should focus on identifying the potential genetic links involved with cases such as the ones presented here.