There are more than 100 genetic syndromes with cutaneous manifestations that are referred to as genodermatoses. There are disorders of: pigmentation (e.g., albinism), cornification (e.g., the ichthyoses and Darier disease), vascularization (e.g., Sturge-Weber syndrome), connective tissue (e.g., Ehlers-Danlos syndrome), metabolism (e.g., phenylketonuria), immune system (e.g., Wiskott-Aldrich syndrome), and DNA repair (e.g., xeroderma pigmentosa). Some textbooks are dedicated to the topic of genodermatoses alone.1 This chapter introduces the topic and illustrates several genodermatoses. We will focus our discussion on Darier disease and pachyonychia congenita as an introduction to the genodermatoses.
A 12-year-old girl presents to her pediatrician with a scaling rash around her neck. A family history reveals that her mother, maternal grandmother, maternal aunt, and uncle all have Darier’s disease. Because this genodermatosis is inherited as an autosomal dominant trait, the pediatrician states that this is likely to be the onset of her Darier disease. The pediatrician prescribes a low potency steroid cream to help the occasional itching that occurs with this new rash. She suggests that the patient also see a local dermatologist. Years later, the young woman returns and her rash is much worse. Upon examination she had red greasy scale around the neck and over the anterior chest (Figures 169-1 to 169-3). The patient states that she was given the diagnosis of Darier disease by the dermatologist but was unable to get an appointment during this acute flare-up. She asked the pediatrician if she could prescribe some 0.1 percent triamcinolone cream because that is what has helped her in the past and she ran out of it 1 month ago. The pediatrician agrees to give her a prescription but encourages her to make an appointment with her dermatologist to see what else can be done. She also notes that the nails have the distinctive red-and-white striping seen in Darier disease (Figure 169-4).
Darier disease with greasy hyperkeratotic scale in a seborrheic distribution involving the face, neck, and chest. As this is an autosomal dominant genodermatosis, many members of her mother’s family have this condition. (Used with permission from Yoon Cohen, MD.)
Darier disease flared up on the posterior neck and upper back in the same patient from Figure 169-1. Note the erythema and greasy yellow hyperkeratotic scale in the seborrheic area. (Used with permission from Yoon Cohen, MD.)
Darier disease on the chest in any seborrheic distribution over the sternum and around the breasts in the same patient from Figure 169-1. (Used with permission from Yoon Cohen, MD.)