What is the basic defect in a particular genetic disease? On the most elementary level, it may be a conversion of a single base in the DNA, a guanine changed to an adenine, a thymine to a cytosine. These most basic defects can now be studied with techniques performed on cellular DNA, such as restriction enzyme digestion. With most genetic skin diseases, direct study of the defective gene has not been undertaken because the defective molecules, particularly those primarily defective, have not yet been identified. Articles in the Journal of Investigative Dermatology have reported progress on two diseases: (1) a disorder of keratinization, ichthyosis vulgaris, and (2) a disorder of dermoepidermal adhesion, recessive dystrophic epidermolysis bullosa.
A markedly thinned-to-absent granular layer characterizes the involved epidermis in ichthyosis vulgaris. The keratohyalin granules that characterize this layer are decreased in number. The amino acid histidine is incorporated in the granular layer of
What Is the Basic Defect in Genetic Disease?. Arch Dermatol. 1986;122(3):337-338. doi:10.1001/archderm.1986.01660150117029