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.