Transient Symptomatic Zinc Deficiency in a Breastfed Infant Associated with Low Zinc Levels in Maternal Serum and Breast Milk Improving after Zinc Supplementation: An Uncommon Phenotype?

Acrodermatitis enteropathica (AE) is a rare, autosomal-recessive disorder of neonatal zinc deficiency due to SLC39A4 (intestinal zinc transporter, Zip4) gene mutation with onset after weaning while breastfeeding during this period will be protective. Transient symptomatic zinc deficiency is also acquired rarely in breastfed infants with increased zinc requirements and/or inadequate concentration of zinc in breast milk. The nursing mothers of transient symptomatic zinc deficiency infants show SLC30A2 (mammary epithelial zinc transporter, ZnT-2) gene mutation and abnormally low zinc levels in the breast milk despite normal serum zinc levels, which do not improve after zinc supplementation. A 2-month-old breastfed male infant had AE-like clinical features of zinc deficiency for two weeks. His symptoms and low serum zinc levels improved rapidly after zinc supplementation. The mother also had low serum and breast milk zinc concentration and both improved after oral zinc therapy indicating a non-heritable phenotype. The relevant literature is reviewed and significance of dietary zinc supplementation during pregnancy/lactation is emphasized.