NORD gratefully acknowledges Timothy J. Fete, MD, MPH, NFED Scientific Advisory Council, Professor Emeritus, Department of Child Health, University of Missouri School of Medicine, and the National Foundation for Ectodermal Dysplasias, for assistance in the preparation of this report.
The ectodermal dysplasias (EDs) are a heterogeneous group of nearly 100 inherited disorders characterized by anomalies in at least two of the structures derived from the embryonic ectoderm, with at least one involving the skin appendages (hair, nails, sweat glands) or teeth. Other tissues derived from the primitive ectoderm that can be involved in EDs include the mammary glands, adrenal medulla, central nervous system, inner ear, retina, optic lens, pigment cells, and branchial arch cartilages. Advances in molecular genetics and developmental biology have led to the identification of the causative genes and developmental pathways in at least 80 of the EDs.
Each of the nearly 100 EDs has its own set of clinical signs and symptoms. Commonly, the conditions will have one or more of the following associated findings:
The molecular causes of these diverse conditions involve many genes and multiple developmental pathways that are necessary for normal formation, structure and function of the ectodermal derivatives. This classification scheme does not include all disorders that affect two or more ectodermal derivatives. Genetic alterations of ED-associated genes that affect only one derivative of the ectoderm would be considered non-syndromic traits of the causative gene. Conditions already included as part of other classifications or groups of diseases (vesiculobullous disorders, palmoplantar keratodermas, etc.) are not included in the ED classification. Complex syndromes that have ED signs, but also major non-ED signs, such as trisomy 21, are also excluded from the ED classification scheme.
The genetic causes of greater than 50% of the ED’s have been determined. The classification scheme clusters the disorders based on genotype, molecular pathway and physical characteristics (phenotype). Categories are:
Conditions that meet the definition of ED but of unknown cause are grouped with other EDs that share the most similar phenotype. Once their genetic cause is identified, they can be classified with the appropriate category or become the anchor of a new cluster, depending on molecular etiology.
The reference listed below from Wright, et al provides a full listing of know ED conditions.
ED’s have been reported from essentially all races, ethnic groups and geographic regions.
Treatment depends upon the specific disease manifestations in the affected individual, and is largely aimed at minimizing symptoms. For most of the ED’s, multidisciplinary management is required, with involvement of primary care physicians, geneticists, dermatologists, multiple dental specialists, nutritionists, speech therapists, otolaryngologists, ophthalmologists, orthopedic surgeons and/or plastic surgeons.
There is ongoing research related to therapies for many of the ectodermal dysplasias. Consultation with a medical geneticist is recommended for most current recommendations.
Of note, intra-amniotic administration of a replacement fusion protein in X-linked hypohidrotic ectodermal dysplasia is showing promise in restoring sweat function and possibly increased dentition in ongoing clinical trials.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Toll-free: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]
Some current clinical trials also are posted on the following page on the NORD website:
https://rarediseases.org/for-patients-and-families/information-resources/info-clinical-trials-and-research-studies/
For information about clinical trials sponsored by private sources, contact:
https://www.centerwatch.com/
For more information about clinical trials conducted in Europe, contact:
https://www.clinicaltrialsregister.eu/
RareConnect offers a safe patient-hosted online community for patients and caregivers affected by this rare disease. For more information, visit www.rareconnect.org.
JOURNAL ARTICLES
Wright JT, Fete M, Schneider H, et al. Ectodermal dysplasias: Classification and organization by phenotype, genotype and molecular pathway. Am J Med Genet A. 2019 Mar;179(3):442-447.
INTERNET
Shah KN. Ectodermal Dysplasia. Medscape. Updated: Feb 11, 2019. www.emedicine.com/derm/topic114.htm Accessed March 5, 2020.
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