Contributor: Gordon K. Klintworth
Hermansky-Pudlak syndrome (Hermansky-Pudlack syndrome, oculocutaneous albinism type 6A, albinism-hemorrhagic diathesis, OMIM #203300) is a specific type of  tyrosinase-positive oculocutaneous albinism with an autosomal recessive mode of inheritance caused by a mutation in the HPS gene but locus heterogeneity may occur. At least 11 mutations in the HPS gene have been identified in this syndrome. One is a frame shift (c.1189delC) Affected individuals have a  mild to severe bleeding diathesis that results from storage, pool-deficient platelets that lack dense bodies. Patients are susceptible to bruising and bleeding.  They also have a ceroid storage disease in the lung and many other tissues. Platelets lack normal levels of adenine nucleotides, calcium and serotonin. Repiratory fibrotic restrictive disease, gingivitis, granulomatous colitis [colitis - granulomatous] and a cardiomyopathy occur. The central nervous system is apparently not involved. Oculocutaneous albinism type VIA is one of at least 10 distinct types with diminished pigmentation of the skin, hair, and eyes. Individuals with oculocutaneous albinism type VIA . These serious and potentially lethal manifestations are unrelated to melanin pigmentation. Affected persons have an abnormal macula (macular hypoplasia [hypoplasia - macula] with abnormal vascular pattern), nystagmus, transparent irises, photophobia and a defective decussation of nerve fibers in the optic chiasm. Visual acuity is impaired and factors that probably contribute to visual impairment include light scatter, light-induced retinal damage, macular hypoplasia, and abnormal retinogeniculostriate projections. Visual acuity is impaired and the retina of each eye has an underdeveloped fovea. The optic fibers are misrouted.