A rare, genetic neurological disease in which the cause of the disease is a 5q31.3 deletion encompassing all or part of PURA gene. The disease is severe neonatal hypotonia-seizures-encephalopathy syndrome due to 5q31.3 microdeletion (MONDO_0017811). Also known as: 5q31.3 microdeletion syndrome, Del(5)(q31.3), monosomy 5q31.3.