Clinical Features of Affected Individuals of Families A and B
Table 1 presents a summary of the clinical features of the four individuals with POC1B mutations. Fundus and OCT images are depicted in Figure 2. The proband (A-II:1) of family A presented with reduced visual acuity in early infancy and mild nystagmus. The diagnosis of incomplete ACHM was contemplated on the basis of ERG showing absent cone function but normal rod responses at the age of 9 years. In the following years, however, visual acuity seemed to deteriorate, and a few years later, her two younger siblings experienced a rapid loss of central vision, suggesting COD (Figures 2A and 2B) in two siblings and CRD in one sibling. No long-term data are available on these three persons. In contrast, B-II:1 was followed for more than 40 years. He was also diagnosed with ACHM in childhood on the basis of the classical signs of reduced visual acuity, photophobia, nystagmus, very poor color vision, and matching ERG responses. In his fifth decade, visual acuity began to drop slowly, and in his sixth decade, degenerative changes consisting of RPE atrophy and bone-spicule pigmentations were noted in the periphery of the inferior quadrant (Figures 2C and 2D). On OCT, changes at the inner-segment ellipsoid zone were observed, suggesting the loss of junctions between inner and outer segments (Figure 2E). ERG at 55 years of age showed absent cone and significantly reduced rod responses. Altogether, the diagnosis changed from isolated cone dysfunction to progressive cone-rod disease. Systematically, he was treated for hypertension and had normal renal function.