Kagami-Ogata syndrome

Kagami-Ogata syndrome (KOS), also known as paternal uniparental disomy of chromosome 14 (UPD(14)pat) syndrome, is a rare imprinting disorder caused by overexpression of paternally expressed genes and loss of maternally expressed genes in the chromosome 14q32 imprinted region. The underlying molecular mechanisms include paternal uniparental disomy of chromosome 14, microdeletions of the maternal differentially methylated region (DMR), or epimutations (hypermethylation) at the MEG3/DLK1 intergenic DMR. The condition is characterized by distinctive features that are apparent from the prenatal and neonatal periods. Key clinical features include a characteristic facial appearance with full cheeks, a depressed nasal bridge, a short nose with anteverted nares, and a protruding philtrum. Affected individuals typically present with a bell-shaped thorax with coat-hanger appearance of the ribs, abdominal wall defects (omphalocele or diastasis recti), polyhydramnios, and placentomegaly during the prenatal period. Severe respiratory difficulties at birth are common due to the small, bell-shaped thorax and may be life-threatening in the neonatal period. Hepatoblastoma is a recognized complication, and developmental delay of variable degree is frequently observed. Joint contractures, particularly of the fingers, and feeding difficulties are also commonly reported. There is no specific curative treatment for Kagami-Ogata syndrome. Management is supportive and multidisciplinary, focusing on respiratory support in the neonatal period (which may require mechanical ventilation), surgical correction of abdominal wall defects, nutritional support for feeding difficulties, and developmental therapies. Surveillance for hepatoblastoma with regular abdominal ultrasound and alpha-fetoprotein monitoring is recommended. With appropriate neonatal intensive care, survival beyond the critical neonatal period has improved, though long-term outcomes vary depending on the severity of thoracic and respiratory involvement.

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