RNA SE T2 (ribonuclease T2) is an enzyme belonging to the RNase T2 family, which is highly expressed in the temporal lobe and fetal brain. The RNASET2 gene is a new member of the extracellular ribonuclease Rh/T2/S-glycoproteins class. It is a single copy gene located in the gene map and is a region 6q27 associated with human malignant tumors and chromosomal rearrangements. RNA SE T2 (ribonuclease T2) is an enzyme belonging to the RNase T2 family, which is highly expressed in the temporal lobe and fetal brain. The RNASET2 gene is a new member of the extracellular ribonuclease Rh/T2/S-glycoproteins class. It is a single copy gene located in the gene map and is a region 6q27 associated with human malignant tumors and chromosomal rearrangements. The absence of RNASET2 is the cause of white matter cystic lesions in the brain without macrocephaly, a pediatric syndrome of white matter encephalopathy that can affect the development of neonatal microcephaly and neurological abnormalities, including psychomotor disorders, seizures, and sensorineural hearing impairment. The brain displays multiple white matter lesions, anterior temporal subcortical cyst walls, abnormal myelin development, ventricular enlargement, and intracranial calcification.