Biallelic variants were identified in PDSS1 (6 families, 6 affected individuals), COQ2 (3 families, 4 affected individuals), COQ4 (1 family, 1 affected individual) and COQ5 (2 families, 2 affected individuals) genes (Fig. 1, Table 1) in patients with simplex or syndromic RP (Table 2). Here, COQ2 is linked to retinitis pigmentosa 1.