Large heterogenous group of genetic disorders characterized by developmental abnormalities in two or more major ectodermal derivatives - hair, teeth, nails, sweat glands, sebaceous glands.
- All have in common: mutations that affect hair follicles and other cutaneous appendeges (teeth, sweat glands, mammary glands)
- Due to absence of reciprocal signals from ectoderm to mesenchyme
Genetic Etiologies
- Transcriptional regulation
- p63, GATA3, EVC
- Cell-cell communications and signaling
- NFkB pathway
- Ectodysplasin (EDA) & related genes: EDAR, EDARADD
- IKK-gamma; IkB kinase (NEMO)
- Developmental proteins
- Shh, Hox7, Msx, Dlx
- Adhesion and intracellular molecules
- Nectin-1, Plakophilin 1, P-cadherin
- Connexins
- Wnt10A
Classification
- “Pure” forms → involve abnormalities in ectodermal derivatives alone
- Syndromic forms → associated disparate manifestations: ophtalmological signs, cleft lip and palate, limb development abnormalities
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