The SIX1 gene, also known as sine oculis homeobox homolog 1, encodes a transcription factor (Six1) that functions as a DNA-binding protein in combination with Eya1, leading to 3.0–4.5% of BOR/BOS cases (Ruf et al., 2004; Wang et al., 2018). The gene discussed is SIX1; the disease is Buschke-Ollendorff syndrome.