Blog Post: February 29th is Rare Disease Day
February 29th is Rare Disease Day. According to rarediseaseday.org, a disease is rare when is effects fewer than 1 in 2000 people; but other groups classify “rare diseases” as 1 in 50,000. There are more than 6000 rare diseases identified--nearly 70% start in childhood, 72% are genetic, and only 5% have an FDA-approved treatment. Examples include cystinosis, turner syndrome, cystic fibrosis, von Willebrand disease, osteogenesis imperfecta, and sickle cell anemia. Many of us will encounter these diseases only within the confines of textbooks or board exam questions--or we may have a family member or patient who has navigated the difficult path of diagnosing and establishing management strategies for these scarce medical entities. Many of these diseases have cutaneous involvement, but specific rare skin diseases include epidermolysis bullosa (EB), hypohidrotic ectodermal dysplasia (HED), basal nevus syndrome, and xeroderma pigmentosa, among others.
EB is a group of mechano-bullous disorders with one common feature: skin fragility. Extracutaneous involvement can also complicate the clinical manifestations of EB. Four majority categories have been classified based on molecular subtypes: simplex, hemidesmosomal, junctional, and dystrophic. Historically, the precise classification required light microscopy to determine the level of tissue separation, but recent molecular-testing advancements help significantly with precise diagnoses.
Often discovered in early childhood, hypohidrotic ectodermal dysplasia (HED) presents with the inability to sweat and cool down body temperature. This condition prevents school-age children from participating in physical education and sports because they must avoid overheating. Access to cool temperatures, light clothing, and air conditioning often requires letters to be written to schools and daycare programs. Extra cutaneous manifestations include frontal bossing, absent eyebrows, and saddle nose deformities.
Basal nevus syndrome, also known as Gorlin-Goltz syndrome, involves mutations of the PTCH1 tumor suppressor gene, which encodes the hedgehog transmembrane receptor protein. This defect promotes the growth of multiple skin-toned basal cell carcinomas on the face, neck, extremities, and trunk. Extracutaneous features include jaw cysts, hypertelorism, cataracts, frontal bossing, and bifid ribs. Individuals with xeroderma pigmentosa (XP) have a 1000-fold increases for BCCs, SCCs, and malignant melanoma due to defective DNA repair when exposed to ultraviolet radiation. XP young children present with acute sensitives and sunburn-like reactions, leading to pigmented macules, severe photodamage, and telangiectasia.
While this list is not exhaustive, mastering genodermatoses can take years; dermatology PAs and NPs often act as important team members managing these rare diseases. Elevate-Derm conferences hope to provide opportunities to discuss, connect, and share experiences with colleagues and experts who treat rare skin diseases.
References:
https://www.rarediseaseday.org/what-is-a-rare-disease/
Sptiz, Joel L. Genodermatoses. Lippincott Williams & Wilkens, 2004
Justin Love, MPAS, PA-C, resides in the blue zone of Loma Linda, CA. He works for Loma Linda University Department of Dermatology. In his spare time, he enjoys any ocean-related activities and spending time with his family.