Pycnodysostosis is a rare autosomal recessive disorder whose gene responsible for this phenotype (CTSK), mapped to human chromosome 1q21, code for the enzyme cathepsin K, a lysosomal cysteine protease; with an estimated incidence of 1.7 per 1 million births. This clinical entity includes micromelic
Loricrin is a glycine-, serine-, and cysteine-rich protein expressed very late in epidermal differentiation in the granular layers of normal human epidermis. Subsequently, loricrin becomes cross-linked by the activity of transglutaminases TGK/E as a major component of the cornified cell envelope by