Inheritance: complex autosomal recessive
Genes which may be affected: HPS1, HPS2/AP3B1, HPS3, HPS4, HPS5, HPS6, HPS7/DTNBP1
Clinical features:
(1) oculocutaneous albinism (see below)
(2) mild bleeding disorder associated with absent or deficient platelet dense bodies (storage granules) on electron microscopy, with absence of irreversible secondary aggregation on platelet function testing
(3) ceroid storage disease
(3a) accumulates in many organs, especially the lung and gastrointestinal tract
(3b) presence in the urine
Clinical criteria for oculocutaneous albinism:
(1) hypopigmentation of hair and skin
(1a) freckles in sun-exposed skin that may coalesce
(1b) white to olive skin that does not tan
(1c) hair color ranges from white to brown
(2) ocular findings:
(2a) nystagmus
(2b) reduced iris pigment
(2c) reduced retinal pigment
(2d) reduced visual acuity secondary to foveal hypoplasia
(2e) decreased decussation (crossing over) of the optic nerve fibers
Complications:
(1) pulmonary fibrosis, which may be fatal
(2) granulomatous colitis
(3) rarely major bleeding
