Background. In children, many inherited or acquired neurological disorders may cause bilateral symmetrical signal intensity alterations in the basal ganglia and thalami.

Objective. To determine the genetic causes of basal ganglia and thalamus lesions in children, and to describe new clilical-MRI-Genetic entities

Methods and material. Retrospective study in Psmmc, Riyadh. 5000 pediatric Brain MRI were reviewed. Patients with toxic, hypoxic, or infectious/autoimmune origin were excluded.

Results. In a period of 7 years, 5000 brain MRI were reviewed, and 250 patients with genetic basal ganglia and thalamus involvement were identified. the ages varied between birth and 14 years. the main causes include biotin thiamine responsive basal ganglia disease (42 patients), mitochondrial diseases (40 patients), inborn error of metabolism (40 patients), genetic non metabolic diseases (40 patients), and non-identified clear etiology in the remaining patients.

several new phenotype are reported for the first time, and a framework for making the appropriate diagnosis and management of basal ganglia involvement is developed.

Conclusion. Recognition and correct evaluation of basal ganglia abnormalities, together with a proper neurological examination and labolratory findings, may enable the identification of each of these clinical entities and lead to early diagnosis and management.