Siitonen et al. (2017) also used SKAT-O in their study to analyze variants associated with early onset PD in Finnish patients. The results showed significant associations to PD in the CEL locus which were not previously identified. However, the validity of the result is questioned by the fact that the CEL region has several indel mutations (Taylor et al., 1991; Siitonen et al., 2017). The gene discussed is CEL; the disease is Parkinson disease.