Waardenburg syndrome (WS) is named after the Dutch ophthalmologist Petrus Johannes Waardenburg, who, in 1947, first described a patient with hearing loss, dystopia canthorum (ie, lateral displacement of the inner canthi of the eyes), and retinal pigmentary differences.
Vitamin A Deficiency-Related Disorders (VADD). The most damaging micronutrient deficiencies in the world are the consequence of low dietary intake of iron, vitamin A, iodine and zinc.Vitamin A deficiency (VAD) is prevalent among the poor whose diets are based mainly on rice or other carbohydrate-rich, micronutrient-poor calory sources.itamin A Deficiency-Related Disorders (VADD). The most damaging micronutrient deficiencies in the world are the consequence of low dietary intake of iron, vitamin A, iodine and zinc.
Dietary Forms. You consume vitamin A in one of two forms. Preformed vitamin A, also known as retinoids, is found in animal sources. Provitamin A carotenoids are from plant sources and include beta-carotene, alpha-carotene and beta-cryptoxanthin.Your body doesnât absorb beta-carotene as efficiently as preformed vitamin A because it must covert the former to retinal or retinol.For example, 12 micrograms of beta-carotene from food is equivalent to 1 microgram of retinol in your body.rovitamin A carotenoids are from plant sources and include beta-carotene, alpha-carotene and beta-cryptoxanthin. Your body doesnât absorb beta-carotene as efficiently as preformed vitamin A because it must covert the former to retinal or retinol.