2.5 Variant validation
Clinically relevant small variants were validated by Sanger sequencing. The CNVs were confirmed by gap-polymerase chain reaction (PCR) and quantitative PCR (qPCR). The primer sequence is available on request. The LOH was validated by Multiplex Ligation-dependent Probe Amplification (MLPA) using SALSA MLPA Probemix ME028 Prader Willi/Angelman (MRC Holland, Amsterdam, the Netherlands).