SSTR5 and Exotropia: In the background of choosing low-frequency (<1%) or non-registered SNVs/InDels in the narrowing-down process, the allele frequency of the 13-nucleotide deletion of SSTR5-AS1, estimated from the heterozygote and homozygote, was high in both patients with idiopathic superior oblique muscle palsy and patients with esotropia or exotropia.