Causes Autosomal-Recessive Mental Retardation with Retinitis Pigmentosa

brain magnetic resonance imaging (MRI) data for the oldest (male) and the youngest (female)affected members of the Mianwali family were used to initially diagnose the patients with nonsyndromic mentalretardation. Although the molar tooth sign (MTS) was observed in the MRI of the female, suggesting a Joubertsyndrome-related disorder (JSRD, MIM 213300), a diagnosis of JSRD was overruled because of the lack of any otherobvious JSRD features. We have since reviewed the MRI images with D. Doherty (University of Washington), and mid-hindbrainfeaturestypicalofJSRD,includingtheMTS,arepresentinbothoftheseindividuals(Figure4EinGordenetal.,this issue