Identification of the KCNJ2 Mutation in a Korean Family with Andersen-Tawil Syndrome and Developmental Delay

Andersen-Tawil syndrome is a rare autosomal dominant disease characterized by the clinical triad of periodic paralysis, long QT with ventricular arrhythmias, and dysmorphic facial or skeletal features. However, the phenotypic heterogeneity and poor disease awareness of this syndrome can hinder an accurate and timely diagnosis. In this study, we describe a Korean family with Andersen-Tawil syndrome with a G215D mutation of the KCNJ2 gene revealed by diagnostic exome sequencing. Two sisters had severe growth restriction, characteristic facial anomalies, and developmental delay. The father carried the same mutation with similar characteristic facial features and short stature. This family lacked periodic paralysis. This report highlights the importance of an exome study for unusual clinical manifestations, such as preand postnatal growth restriction, developmental delay, and the lack of a critical diagnostic clue, such as periodic paralysis.