Discussion
The EDs are hereditary genetic disorders characterized by primary developmental defects of two or more ectodermal structures, one of which is either hair, teeth, nail or sweat glands. X-linked hypohidrotic form (Christ Touraine Syndrome) with absent or reduced sweat production is the most common ED.(5) However autosomal dominant/recessive cases of hypohidrotic EDs have been reported.(3) Clinically they present with hypotrichosis i.e, fine, slow growing scalp and body hair and sparse eyebrows with hypodontia and nail anomalies.(6) Both deciduous and permanent teeth are typically peg-shaped and reduced sweat production results into dry skin and heat intolerance.(5)(6)
Hydrotic ectodermal dysplasia (Clouston syndrome) with autosomal dominant inheritance affects the teeth, hair and nails but sweating is normal. The pathophysiology usually involves mutations in connexin gene leading to hypotrichosis (partial or total alopecia), brittle hair, dystrophic nails, clubbing, finger pulp dermal ridges and keratoderma. Eye lashes and eye brows are sparse or absent. Paronychial infections are commonly observed. (7) The management involves keratolytics and emollients for palmoplantar keratoderma. Minoxidil has been used to enlarge miniaturized hair follicles while wigs can be used in cases of total alopecia. Nail dystrophy can be addressed with professional pedicures and manicures. (8)
The other features commonly observed in EDs are frontal bossing, sunken cheeks, depressed nasal bridge, thick everted protuberant lips, wrinkled hyperpigmented periorbital skin, and a large low set of ears.(5) The most common oral sign is hypodontia or anodontia of deciduous and permanent dentition associated with conical teeth. The pathophysiology of ED involves the genetic defect in complicated network of signalling pathways that coordinates the formation and function of ectodermal structures. Some of these important molecular pathways are Hedgehog, Wingless, TNF-α, NF-kB, ED and p63 signalling pathways, Gap junctions-connexin pathway and Axin pathway.(3)(4)
The diagnosis of ED can be made based on family history, thorough clinical evaluation, molecular analysis and imaging studies. In our case, permanent central incisor and canine teeth are missing in lower jaw along with dry, rough skin. There was absence of distal phalanx of right middle finger with missing nail plate. Molecular analysis couldn’t be done in our resource constrained settings. OPG and hand radiographs were taken to confirm the clinical diagnosis. These clinical features and imaging studies were suggestive of hypohidrotic ED.