title: Joubert syndrome and related disorders, prenatal diagnosis with ultrasound and magnetic resonance imaging.
abstract: Joubert syndrome (JBTS) is an autosomal recessive disorder characterized by intellectual disability, hypotonia, ataxia, tachypnea/apnea, and abnormal eye movements. A pathognomonic midbrain-hindbrain malformation seen on cranial magnetic resonance imaging (MRI), which consists of hypoplasia of the midline cerebellar vermis that resembles the cross-section through a molar tooth, has been described previously. The molar tooth sign is defined by a peculiar appearance resembling a molar tooth secondary to an abnormally deep interpeduncular fossa and enlarged superior cerebellar peduncles on axial images at the pontomesencephalic level. The term Joubert Syndrome and Related Disorders (JSRD) has recently been adopted to describe all disorders presenting the "molar tooth sign" (MTS) on brain imaging. JSRD is characterized by lack of decussation of the superior cerebellar peduncles, central pontine tracts and corticospinal tracts suggesting defective axon guidance. Prenatal sonographic findings in fetuses with JSRD are relatively nonspecific and include increased nuchal translucency, enlarged cisterna magna, cerebellar vermian agenesis, occipital encephalocele, ventriculomegaly and polydactyly. We report a case of JSRD detected prenatally at 23 weeks of gestation. The fetus in the present case had a normal karyotype. Sonographic features of the fetus included polydactyly, partial vermian hypoplasia, dilated 4(th) ventricle and mild ventriculomegaly which were also confirmed by prenatal MRI. MTS was demonstrated in a postnatal MRI after pregnancy termination.
authors.affiliation: Department of Gynecology and Obstetrics, Faculty of Medicine, Başkent University, Adana, Turkey.
authors.forename: Can Tekin
authors.initials: CT
authors.lastname: Iskender
authors.affiliation: Department of Gynecology and Obstetrics, Faculty of Medicine, Başkent University, Adana, Turkey.
authors.forename: Ebru
authors.initials: E
authors.lastname: Tarım
authors.affiliation: Department of Radiology, Faculty of Medicine, Başkent University, Adana, Turkey.
authors.forename: Ozlem
authors.initials: O
authors.lastname: Alkan
keywords: Joubert syndrome; cerebellar vermian agenenesis; polydactyly; prenatal diagnosis; ultrasonography