Family 1 comprises two healthy parents and an affected son. Their DNA was sent to Complete Genomics, Inc. for whole genome sequence analysis. The genomics data was analyzed under a de novo model where we identified two high-quality private missense mutations in the affected individual, which are homozygous-reference genotypes in both parents (data obtained from the masterVar file from each genomic data set http://www.completegenomics.com/customer-support/documentation/100357139.html); both mutations were absent in the 1,000 Genomes project, dbSNP and in the ESP 6,500 project. The first de novo mutation in gene MYO1H altersaminoacid (aa) 83 of protein NP_001094891.3 from an Alanine to Valine, however there are no known human disorders associated with aa changes in MYO1H (according to OMIM). The second de novo mutation, in gene MAGEL2, generates a 1-base frameshift in protein NP_061939.3 (1,249 aa) starting at aa 551 and continuing until the new frame reaches a termination codon at aa 701. The MAGEL2 mutation was validated by Sanger sequencing using PCR reactions with primers Val1_Fw and Val1_Re (Supplementary Table 2). The change in the protein is biologically significant and given the fact that MAGEL2 is located in a maternally imprinted region 15q11.2, we proceeded to determine the phase of the mutation.
