Independent segregation of fundus albipunctatus and the transthyretin (prealbumin) gene

A defect in the visual cycle has been suspected in patients with fundus albipunctatus (FALB), rendering genes encoding visual cycle components etiologic candidates. One such component is the retinoid and thyroxine transport protein transthyretin (TTR, prealbumin) which in the eye is synthesized only in the retinal pigment epithelium and is believed to play a role in retinal retinoid transport. The authors established polymerase chain reaction conditions that allow rapid assay of TTR alleles as defined by Msp1 and Fnu4H1 restriction fragment length polymorphisms. In a candidate gene analysis of an affected family, they demonstrate independent segregation of the TTR and FALB disease loci. These results exclude the possibility that a TTR gene defect causes FALB in this family.