Sanger sequencing of RTEL1 (RefSeq accession number NM_032957.4) in the index case, her unaffected sibling, and her parents confirmed the presence and segregation of mutations c.2288G>T (p.Gly763Val) and c.3791G>A (p.Arg1264His) (this latter mutation is based on the alternative splice variant uc021wge.1 from the UCSC Genome Browser; DCR family 129 in Table 1 and Figure 1A) with disease. This suggests that these mutations could be causal in this family.