Introduction
Ectodermal dysplasia (ED) is a rare heterogenous group of heritable
disorder that manifests as developmental defects of two or more tissues
of ectodermal origin.(1) The skin, hair, nails,
eccrine glands, and teeth are the tissues primarily
affected(2). Other tissues of ectodermal origin that
may be involved are mammary gland, central nervous system, external ear,
cornea, conjunctiva, melanocytes, and lacrimal gland and
duct(3)(4). All patterns of inheritance like autosomal
recessive/dominant, X-linked and mitochondrial have been described. The
ED which is congenital, diffuse and nonprogressive, has an estimated
incidence of around seven cases per 100,000 live
births(1). Traditionally ectodermal dysplasia is
classified into two types based on sweat gland function. The first one
is X-linked hypohidrotic type (Christ-Siemens-Touraine syndrome)
presenting with a classical triad of hypodontia, hypohidrosis (reduced
or absent sweating), and hypotrichosis. In contrast to that, the second
one is the hydrotic type (Clouston syndrome) characterized by normal
sweat gland function with other ectodermal defects and is inherited in
autosomal dominant manner(1). But this simple
classification has failed to address the anomalies associated with nail,
hair and teeth in various forms of ED.