Iron Deficient Toxic Milk Leads to the Mask Phenotype in Hephaestin Knockout Mice

The study investigated the effects of iron deficiency in hephaestin knockout (Hp KO) mice, focusing on a specific hair loss phenotype known as the "mask" phenotype. Hephaestin is crucial for intestinal iron transport, and its absence leads to iron accumulation in the intestine. Researchers observed that neonates born to Hp KO dams exhibited truncal hair loss, which resolved after weaning. This phenotype was also present in pups born to mothers with an intestine-specific knockout of Hp, indicating that maternal intestinal Hp deficiency was responsible. Cross-fostering studies showed that wild-type pups nursed by Hp KO dams developed the hair loss phenotype, while those nursed by wild-type dams did not. Histological analysis revealed disorientation and keratinization of hair follicles in affected pups. The findings suggested that low iron levels in the milk, described as a "toxic milk" phenotype, were responsible for the observed hair loss.