obsolete_Joubert syndrome and related disorders true JSRD Replaced with Mondo term. 3.41.0 orphanet http://purl.obolibrary.org/obo/MONDO_0015369 Joubert syndrome (JS) and related disorders (JSRD) are a group of developmental delay/multiple congenital anomaly syndromes in which the mandatory feature is the ``molar tooth sign'' (MTS), a complex midbrain-hindbrain malformation recognizable on brain imaging. The MTS is characterized by cerebellar vermis hypodysplasia, thickening and malorientation of the superior cerebellar peduncles and abnormally deep interpeduncular fossa.