Pili Trianguli et Canaliculi Is a Defect of Inner Root Sheath Keratinization

Congenital woolly hair without P2RY5 mutation

Congenital woolly hair is a disorder with structural defects of the hair shafts. Curled hairs are noticed at birth or soon after birth and often improve with age. Some cases of woolly hairs are associated with systemic or other skin diseases. Congenital woolly hair without any associated disorder is inherited in an autosomal dominant or autosomal recessive manner. Recently, mutations in P2RY5 gene, encoding a G-protein coupled receptor, have been shown to be responsible for autosomal recessive woolly hair. Here, we report the second Japanese case of congenital woolly hair, showing no P2RY5 gene mutation.

Uncombable hair syndrome, mental retardation, single palmar crease and arched palate in a patient with neurofibromatosis type I

A 2-year-old girl presented with hair that naturally stood out from her scalp. Her mother reported that the girl's hair had been impossible to comb since the first month of life. The child's eyebrows and lashes were normal. Scanning electron microscopy confirmed the presence of grooving on the hair shaft. Moreover, eight cafè-au-lait macules larger than 5 mm on the trunk and the limbs, and freckles in the axillary regions were observed. Neurologic examination showed some difficulties in motor organization and dyslalia. Magnetic resonance imaging illustrated multiple cerebral hamartomas. Molecular analysis disclosed microdeletion of gene 17q.11.2. Additional features included arched palate, a single palmar crease on one hand and low-set ears, which, together with bone abnormalities, have been previously associated with uncombable hair. This is the first report, to the best of our knowledge, of uncombable hair syndrome in a patient with neurofibromatosis type I.

K25 (K25irs1), K26 (K25irs2), K27 (K25irs3), and K28 (K25irs4) represent the type I inner root sheath keratins of the human hair follicle

The recent elucidation of the human type I keratin gene domain allowed the completion of the so far only partially characterized subcluster of type I keratin genes, KRT25-KRT28 (formerly KRT25A-KRT25D), representing the counterparts of the type II inner root sheath (IRS) keratin genes, KRT71-KRT74 (encoding proteins K71-K74, formerly K6irs1-K6irs4). Here, we describe the expression patterns of the type I IRS keratin proteins K25-K28 (formerly K25irs1-K25irs4) and their mRNAs. We found that K25 (K25irs1), K27 (K25irs3), and K28 (K25irs4) occur in the Henle layer, the Huxley layer, and in the IRS cuticle. Their expression extends from the bulb region up to the points of terminal differentiation of the three layers. In contrast, K26 (K25irs2) is restricted to the upper IRS cuticle. Apart from the three IRS layers, K25 (K25irs1), K27 (K25irs3), and K28 (K25irs4) are also present in the hair medulla. Based on previous, although controversial claims of the occurrence in the IRS of various "classical" epithelial keratins, we undertook a systematic study using antibodies against the presently described human epithelial and hair keratins and show that the type I keratins K25-K28 (K25irs1-K25irs4) and the type II keratins K71-K74 (K6irs1-K6irs4) represent the IRS keratins of the human hair follicle.