Kagami-Ogata Syndrome: An Anomaly of the Ribs as a Pathognomonic Feature for the Clinical Diagnosis of an (epi)Genetic Syndrome

Abstract

Within 4 years (2014-2017), we genetically diagnosed 2 newborns with Kagami-Ogata syndrome (OMIM #608149). As fetuses they exhibited prenatal polyhydramnios and in 1 case hepatomegaly. After birth, the newborns suffered from respiratory distress. Typical phenotypic features, such as muscular hypotonia, a protruding philtrum, full cheeks and a depressed nasal bridge, were present. Chest X-rays revealed coat-hanger ribs and a bell-shaped thorax, suggestive of the entity. Kagami-Ogata syndrome is caused by an aberrant gene expression of chromosome 14 and was first described in 1991. Possible causes are paternal uniparental disomy of chromosome 14, epimutations and microdeletions. Approximately 70 cases have been reported in the literature, with 34 comprising the original cohort of M. Kagami and T. Ogata. The incidence of the disease is unknown. Patients often manifest a developmental delay and an intellectual disability, although in the meantime cases with milder clinical courses have been described. In the cohort of Kagami and Ogata 3 patients developed hepatoblastoma, which is a common feature in another imprinting disorder, namely the Beckwith-Wiedemann syndrome. Therefore, hepatoblastoma should be considered in follow-up examinations.