Mothers with missense or nonsense mutations in the ZNT2 gene secrete zinc-deficient milk (75–95% reduction), and thus infants exclusively breast-fed by mothers carrying the mutation experience transient neonatal zinc deficiency (TNZD; OMIM 608118) [87,128,129,130,131]. Here, SLC30A2 is linked to zinc deficiency, transient neonatal.