Absence of otoconia in a human infant.

Temporal bone specimens were obtained at autopsy from a six-week-old victim of sudden infant death syndrome. The inner ears were microdissected and studied by a combination of light and scanning electron microscopy. Otoconia were completely absent from the sensory organs of the saccule and utricle on both sides. However, the gelatinous otoconial membranes, neuroepithelia, and innervation were normal. In parallel with unusually light pigmentation of the skin in this Negro infant, relatively few melanocytes were found in the membranous walls of the saccule and utricle. No abnormalities were present in other inner ear structures. This anomaly, which we believe was congenital in nature, is strikingly similar to a genetically determined inner ear defect which has been extensively studied in experimental animals.