Difference between RP2 and RP3 phenotypes in X linked retinitis pigmentosa

Abstract

XLRP is a heterogeneous class of rod degenerative disorders with no clear phenotypic differentiation between the two genetic loci RP2 and RP3. There is a continuum of clinical presentations which can be seen in both RP2 and RP3, but the features within a given family tend to be consistent. However, interfamilial variability is prevalent leading to a wide range of clinical presentations and more than one abnormal allele at each gene locus cannot be excluded.

Mutations ofRPGR in X-linked retinitis pigmentosa (RP3)

“…No obvious difference was noted by Flaxel et al [1999] or Bailey et al [2001]. However, Sharon et al [2000] compared the visual function of patients with identified mutations in RPGR versus RP2 and found that there is a difference in the severity of the retinal degeneration: despite considerable overlap, patients with mutations in RPGR have on average smaller visual fields and more severely reduced full field ERG amplitudes.…”

Retinal Histopathology of an XLRP Carrier with a Mutation in the RPGR Exon ORF15

“…Clinically the XLRP subclass encompasses the most severe forms of RP, with early onset of night blindness, rapid constriction of visual ®elds and eventual loss of central acuity . The presence of genetic heterogeneity and the absence of clear phenotypic differences between retinal degenerations caused by RP2 and RP3 has made it dif®cult to differentiate clinically among the XLRP disease loci (Flaxel et al, 1999;Rosenberg et al, 1999).…”

Gene Augmentation for X-Linked Retinitis Pigmentosa Caused by Mutations in RPGR

“…Carrier females with RPGR mutations also show a wide spectrum of retinal disease expression ranging from asymptomatic with normal electrophysiological and psychophysical test results to very severe retina-wide disease (Andreasson et al 1997;Jacobson et al 1997;Weleber et al 1997;Bauer et al 1998;Fishman et al 1998;Flaxel et al 1999;Ayyagari et al 2002;Lorenz et al 2003;Ebenezer et al 2005;Jin et al 2006;Ruddle et al 2009;Thiadens et al 2011). There tends to be significant interocular asymmetry of disease severity in most carriers (Jacobson et al 1989;Weleber et al 1997;Fishman et al 1998;Lorenz et al 2003;Ebenezer et al 2005).…”

“…There tends to be significant interocular asymmetry of disease severity in most carriers (Jacobson et al 1989;Weleber et al 1997;Fishman et al 1998;Lorenz et al 2003;Ebenezer et al 2005). A distinct golden tapetal-like reflex, hypothesized to be located at cone inner segments (Cideciyan and Jacobson 1994), or peripheral photoreceptor outer segments (Berendschot et al 1996), has been variably described in a subset of female carriers of RPGR mutations (Andreasson et al 1997;Jacobson et al 1997;Weleber et al 1997;Bauer et al 1998;Fishman et al 1998;Flaxel et al 1999;Ayyagari et al 2002;Lorenz et al 2003;Ebenezer et al 2005;Jin et al 2006;Ruddle et al 2009;Thiadens et al 2011).…”