OC23.04: Prenatal imaging of ciliopathies

Human ciliopathies are hereditary conditions caused by defects of proteins expressed at the primary cilium. Disruptions due to mutations in cilia-centrosomal proteins can induce severe alterations in ciliary function, which may be manifest in multiple organ systems. Since the prenatal findings of ciliopathies are subtle, the object of this study is to review diagnostic imaging features in order to facilitate prenatal diagnosis, with the intent to assist in counselling of prospective parents. Prenatal sonographic and MRI records from British Columbia were reviewed to identify fetuses with abnormalities suspected to be due to ciliopathies. Prenatal imaging findings were correlated with postnatal imaging, clinical and/or autopsy diagnoses. A total of 32 fetuses were identified with findings consistent with ciliopathies. One family had two affected pregnancies. The imaging findings most commonly suggestive of ciliopathies were echogenic, enlarged and/or cystic kidneys (27/32 cases); polydactyly (14/32) and midline brain anomalies (12/32). Specific diagnoses included: Meckel syndrome (7); autosomal recessive polycystic kidney disease, nephronophthisis and Bardet-Biedl syndrome (12); skeletal dysplasia (6); autosomal dominant polycystic kidney disease (1); and Joubert syndrome and related disorders (4). Molar tooth sign was see in 4 cases of Joubert syndrome prospectively and retrospectively in 1 case of Meckel syndrome. Ciliopathies are rarely recognised in the fetus but can be appreciated by observing subtle imaging findings in kidneys, brain and extremities. Recognition of one characteristic finding should prompt search for corroborative abnormalities. Since ciliopathies are predominantly autosomal recessive with a recurrence risk of 25%, it is important to recognise antenatal findings in order to counsel prospective parents.