2.3 |. Identification of genetic variants

We isolated each genomic DNA sample from peripheral blood using the QIAamp DNA Blood Kit (Qiagen, Hilden, Germany). Coding regions were amplified with SureSelect (Agilent Technologies, Santa Clara, CA, USA), and paired-end sequencing of base pairs was performed on an Illumina HiSeq2500 Platform (Illumina Cambridge, Cambridge, UK) as described previously (Yi et al., 2017). We aligned sequence data using a BWA-MEM algorithm and analyzed it using SureCall 2.1 (Agilent Technologies). Exome data were analyzed with an average coverage depth of 4× to identify rare variants. To confirm the rare variants identified by PDE3A exome sequencing, we amplified PDE3A exons using the polymerase chain reaction (PCR). We purified PCR products using a PCR purification kit (NucleoGen, Ansan, South Korea) and directly sequenced purified samples using an ABI Prism 3700Xi Genetic Analyzer (Applied Biosystems, Waltham, MA, USA) to confirm the mutation. All primers used in PDE3A exome sequencing are described in Supplement Table 1.