Correlation of visual acuity and ocular pigmentation with the 16-bp duplication in the HPS-1 gene of Hermansky-Pudlak syndrome, a form of albinism

Objective: Patients with the Hermansky-Pudlak syndrome (HPS), a form of alb inism, were studied. The first purpose of this investigation was to determi ne if visual acuity was related to the presence or absence of the 16-bp dup lication in the HPS-1 gene. The second was to study the correlation between the degree of ocular pigmentation and visual acuity within the two genetic groups described above. Design: Cross-sectional study of a series of consecutive patients. Participants: Forty-nine patients with HPS with or without the 16-bp duplic ation in HPS-1. Methods: Best corrected visual acuity (VA) using Early Treatment Diabetic R etinopathy Study (ETDRS) charts, photographic gradings of iris transillumin ation and of visibility of choroidal Vessels in the macula (macular transpa rency). Main Outcome Measures: Association between VA and the presence or absence o f the 16-bp duplication in HPS-1 and correlation between VA and the degree of iris transillumination (iris score) and macular transparency (fundus sco re), as determined by masked reading of photographs, with respect to the pr esence or absence of the 16-bp duplication in HPS-1 were the main outcome m easures. Results: The VA of the better eye did not differ between the two genetic gr oups (P = 0.322, two-sided t test), Spearman's rank correlation between VA and iris scores in 39 eyes of 20 patients with the duplication was not stat istically significant (P = 0.698) but was statistically significant in 36 e yes of 19 patients without the duplication (P < 0.001). Among all patients, the correlation was statistically significant (r = -0.36 in RE and r = -0. 51 in LE). Spearman's rank correlation between VA and fundus scores in 36 e yes of 19 patients with and 34 eyes in 18 patients with and without the dup lication was statistically significant (P = 0.035 and P = 0.008, respective ly). Among all patients, it was also statistically significant (r = -0.39 i n RE and r = -0.45 in LE). Conclusions: The mean VA of the better eye did not differ in patients with the 16-bp duplication compared with those without the duplication. There we re statistically significant associations between VA and the iris score and the fundus score except for the VA and iris scores in patients with the 16 -bp duplication. However, because of the variability of VA, these associati ons were not large enough for useful prediction of VA based on the degree o f ocular pigmentation. (C) 2000 by the American Academy of Ophthalmology.