Heritage characteristics reported by a group of African-Americans who exhibit the pigment dispersion syndrome: A case-control study

Purpose: To investigate the racial heritage of a group of African-Americans who exhibit the pigment dispersion syndrome (PDS). Subjects and methods: Ten unrelated African-American PDS patients (age range 13-59) from a primary eye care population in Chicago, Illinois, USA, were interviewed to determine their racial heritage. Since Caucasian and Native American heritage were commonly reported, 101 unaffected African-American control subjects (age range 18-55) were also interviewed to determine the reported frequency of these specific racial heritage characteristics. Results: Some degree of Caucasian heritage was reported by 100% of the PDS subjects and by 46.5% of controls. Native American heritage was reported by 90% of the PDS subjects and by 71.3% of controls. Based on these data, the PDS subjects were significantly more likely to report Caucasian heritage (Fisher's exact test, P=0.001) but they were not significantly more likely to report Native American heritage (P=0.282). In addition, the PDS subjects were significantly more likely to report Caucasian heritage from both parents (P=0.024) and more likely to report a combination of both Caucasian and Native American heritage (P=0.0006) than corresponding controls. In general, the PDS subjects had 'light' or 'medium' complexions. Conclusion: Results from this analysis are consistent with the hypothesis that non-African heritage, particularly Caucasian, is likely to be prevalent in the background of African-Americans who exhibit PDS. It is suggested that non-African heritage may not only be important for the transference of PDS causing genes, but it may also influence factors such as degree of iris pigmentation and rigidity which could influence iris contour and the subsequent expression of PDS in those who are genetically predisposed. Further investigation is needed to study the factors that influence the expression and severity of PDS among African-Americans, a population which traditionally has been considered to be rarely affected by this condition.