Acrodermatitis enteropathica

Acrodermatitis enteropathica (AE) is a rare inherited disorder of zinc metabolism caused by mutations in the SLC39A4 gene, which encodes a zinc transporter protein (ZIP4) primarily expressed in the small intestine. This defect leads to impaired intestinal absorption of zinc, resulting in severe zinc deficiency that affects multiple body systems. The condition was first described by Brandt in 1936 and further characterized by Danbolt and Closs in 1942. Without treatment, the disease can be life-threatening, particularly in infancy. The classic clinical triad of acrodermatitis enteropathica includes dermatitis (skin inflammation), diarrhea, and alopecia (hair loss). The characteristic skin lesions are erythematous, scaly, and often vesiculobullous or psoriasiform plaques that typically appear around body orifices (perioral, perianal, periocular) and on the extremities (hands, feet, elbows, knees). These lesions are prone to secondary infection with bacteria and Candida. Additional features include nail dystrophy (ridging, paronychia), irritability, failure to thrive, photophobia, delayed wound healing, and immune dysfunction leading to increased susceptibility to infections. Neuropsychiatric symptoms such as emotional disturbances and cognitive impairment may also occur. In breastfed infants, symptoms typically manifest after weaning, as breast milk contains zinc-binding ligands that facilitate absorption. The diagnosis is confirmed by demonstrating low serum zinc levels (typically below 50 µg/dL) and low serum alkaline phosphatase (a zinc-dependent enzyme), along with molecular genetic testing of the SLC39A4 gene. Treatment consists of lifelong oral zinc supplementation, usually in the form of zinc sulfate or zinc gluconate, at doses of 1–3 mg/kg/day of elemental zinc. With appropriate zinc replacement therapy, symptoms resolve rapidly and completely, and patients can lead normal lives. Regular monitoring of serum zinc levels is essential to ensure adequate supplementation and prevent toxicity.

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