IDH3A and glioma: High-grade gliomas in children, particularly in infants younger than 3 years old, have better life prognoses than high-grade gliomas in older children and adults, and do not have alterations of the histone H3.1 or H3.3 gene, which are found in tumors in older children at a high frequency, or of the isocitrate dehydrogenase (IDH) 1 or IDH2 gene, which are found in tumors in young adults at a high frequency.