Mer tyrosine kinase (MERTK) is essential for the efficient engulfment of POS by RPE (Finnemann and Nandrot, 2006) and mutations in Mertk have been identified in patients with retinitis pigmentosa (Gal et al., 2000; Al-khersan et al., 2017; Tagawa et al., 2021). Here, MERTK is linked to retinitis pigmentosa.