Because many presume pigment dispersion syndrome (PDS) and pigmentary glaucoma (PG) are inherited in an autosomal dominant manner, researchers in Iowa examined relatives of patients with PDS and PG to determine the diseases’ heritability. The prospective, cross-sectional study found the risk of a first-degree family member developing PDS or PG was 10.10%.

Researchers began by recruiting 101 patients with PDS, of whom four had PDS without ocular hypertension (OHT) or glaucoma, six had PDS and OHT and 91 had PG. The criteria for PDS were two of three signs: Krukenberg spindle, mid-peripheral iris trans-illumination defects (TIDs) and heavy trabecular meshwork (TM) pigmentation. Criteria for PG included PDS and two of three signs: intraocular pressure greater than 21mm Hg, glaucomatous optic nerve damage and glaucomatous visual field loss.

After examining 99 first-degree relatives to determine the probability of familial transmission, 10 were diagnosed with PDS (one with PDS alone, two with PDS and OHT and seven with PG). Eight of the 10 affected family members showed moderate to heavy TM pigmentation and either Krukenberg spindle or TIDs. 

The study identified seven families with at least two affected members. Specifically, it noted transmission of PDS from father-to-daughter (one family), father-to-son (three families), mother-to-son (two families) and mother-to-daughter (one family). The frequent vertical transmission of disease in these pedigrees suggested that some cases of PDS may have an autosomal dominant mode of inheritance.

Researchers noted that the risk for the predominantly Caucasian Iowa population may not be the same in all other populations. They also suggested that they may have missed some cases of PDS/PG because some relatives were too young to develop the disease or old enough to have have lost signs of PDS.