“…Multiple studies reporting clinical features of XLRS in a series of families have been reported world-wide (Apushkin et al, 2005b; Atchaneeyasakul et al, 2010; Eksandh et al, 2000; Forsius et al, 1963; George et al, 1995, 1996; Hewitt et al, 2005; Kellner et al, 1990; Lesch et al, 2008; Pimenides et al, 2005; Renner et al, 2008; Riveiro-Alvarez et al, 2009; Shinoda et al, 2000; Shukla et al, 2007; Simonelli et al, 2003; Vainio-Mattila et al, 1969; Xu et al, 2011). The penetrance of XLRS is almost complete but clinical expression is highly variable (Sieving, 1998).…”