Hereditary hypercarotenemia and vitamin A deficiency

Hereditary hypercarotenemia and vitamin A deficiency is a rare genetic metabolic disorder caused by mutations in the BCO1 (beta-carotene oxygenase 1) gene, which encodes the enzyme responsible for converting beta-carotene (provitamin A) into retinal (vitamin A). Because this enzymatic conversion is impaired, affected individuals accumulate beta-carotene in the blood and tissues, leading to hypercarotenemia, which manifests as a yellowish-orange discoloration of the skin (carotenoderma), particularly noticeable on the palms, soles, and nasolabial folds. Importantly, unlike jaundice, the sclerae (whites of the eyes) remain white. Despite adequate dietary intake of carotenoid-rich foods, affected individuals may develop vitamin A deficiency because they cannot efficiently convert beta-carotene into its active form. Vitamin A is essential for vision, immune function, skin integrity, and reproduction. Consequently, patients may experience symptoms related to vitamin A deficiency, including night blindness, dry eyes (xerophthalmia), impaired immune responses, and skin changes. The severity of symptoms can vary depending on the degree of enzyme impairment and whether preformed vitamin A (retinol) from animal sources is present in the diet. Management of this condition focuses on ensuring adequate intake of preformed vitamin A (retinol) from dietary sources such as liver, dairy products, eggs, and fish, or through direct retinol supplementation, thereby bypassing the defective beta-carotene conversion pathway. With appropriate dietary modification and supplementation, the consequences of vitamin A deficiency can generally be prevented or reversed. Genetic counseling is recommended for affected families. The condition is considered very rare, and awareness among healthcare providers is important to avoid misdiagnosis.

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