iRhom1 and iRhom2 are inactive homologues of rhomboid intramembrane serine proteases lacking essential catalytic residues, which are necessary for the maturation of TNFα-converting enzyme (TACE). In addition, iRhoms regulate epidermal growth factor family secretion. The functional significance of iRhom2 during mammalian development is largely unclear. We have identified a spontaneous single gen...

Afro-ethnic hair is different from Caucasian and Asian hair and has unique features. Ethnic hair is more prone to certain conditions or diseases. Such diseases are not only related to the fragile inner structure of the hair, but also to the cultural habits of hairstyles that often exert traction forces upon the pilosebaceous follicle. Women with African hair subject their hair to chemical treat...

The hair coat, which keeps most mammals warm, dry and protected from harmful elements, requires a constant supply of new hairs throughout the lifetime of the animal. To produce new hairs, existing follicles undergo cycles of growth (anagen), regression (catagen) and rest (telogen). During each anagen phase, follicles produce an entire hair shaft from tip to root; during catagen and telogen, fol...

Netherton syndrome is a rare autosomal recessive condition with variable expression. It comprises an ichthyosiform dermatitis and erythroderma of variable intensity associated with hair abnormalities and features of atopy. The pathognomic (required for diagnosis) feature is trichorrhexis invaginata identified by microscopic examination of hair shaft. Ichthyosis linearis circumflexa is ano...

Pili torti also known as 'twisted hairs' (Latin: pili=hair; torti=twisted) is a rare, congenital or acquired clinical presentation, in which the hair shaft is flattened at irregular intervals and twisted 180º along its axis. It is clinically characterized by fragile, brittle, coarse and lusterless hairs, due to uneven light reflection on the twisted hair surface. Pili torti may be associated wi...

Griscelli syndrome is a rare disease characterized by pigment dilution, partial albinism, variable cellular immunodeficiency, and an acute phase of uncontrolled T-lymphocyte, and macrophage activation. Griscelli et al described this syndrome in 1978. Since then, only in approximately 60 cases have been reported, most from the Turkish, and Mediterranean population. In microscopic examination, si...

Although the hair shaft is derived from the progeny of keratinocyte stem cells in the follicular epithelium, the growth and differentiation of follicular keratinocytes is guided by a specialized mesenchymal population, the dermal papilla (DP), that is embedded in the hair bulb. Here we show that the number of DP cells in the follicle correlates with the size and shape of the hair produced in th...

In this paper, we use the method of independent contrasts to study body size relationships between pocket gophers and their chewing lice, a host-parasite system in which both host and parasite phylogenies are well studied. The evolution of body size of chewing lice appears to be dependent only on the body size of their hosts, which confirms the 1991 findings of Harvey and Keymer. We show that t...

Epithelial stem cells (EpSCs) in the hair follicle bulge are required for hair follicle growth and cycling. The isolation and propagation of human EpSCs for tissue engineering purposes remains a challenge. Here we develop a strategy to differentiate human iPSCs (hiPSCs) into CD200(+)/ITGA6(+) EpSCs that can reconstitute the epithelial components of the hair follicle and interfollicular epidermi...