Footnotes Source of Support: Nil Conflict of Interest: None

Footnotes Source of Support: Nil Conflict of Interest: None declared.
Ectodermal dysplasia (ED) is a term used to describe a heterogeneous group of rare, inherited disorders mainly characterized by dysplasia of ectodermal tissues and occasionally of mesodermal tissues of the developing embryo.[1,2,3] ED is characterized by the triad of signs comprising of sparse hair (atrichosis or hypotrichosis) [Figure 1], abnormal or missing teeth (anodontia or hypodontia) [Figure 2], and inability to sweat due to lack of sweat glands (anhidrosis or hypohidrosis).[3,4] In addition, nail dystrophy and palmoplantar hyperkeratosis is usually present.[5,6] The sensorineural and adrenal tissues are also affected at various degrees.[1] Figure 1 Extra oral photographs of patients with ectodermal dysplasia Figure 2 Intra oral photographs of patients with ectodermal dysplasia.

Note- partial anodontia and conical-shaped teeth ED was first reported in 1792 by Danz.[7] In 1838, Wedderburn documented ED in a letter to Charles Darwin; describing 10 cases of Hindu male family members.[8] Nicolle and Hallipre in 1895 first described hydrotic ED in a French-Canadian family.[9] In 1913, Christ characterized hypohydrotic ectodermal dysplasia as a congenital ectodermal defect.[7] In 1921, Siemens described the X-linked nature of inheritance. The term ED was coined in 1929 by Weech.[3] In 1936, Touraine described the wide range of features in ED. Thus, hypohydrotic ED is also known as Christ-Siemens-Touraine syndrome.[10] Clouston in 1939 used the term anhydrotic ED.

[11] Felsher in 1944 changed the adjective anhydrotic to hypohydrotic because the persons termed as anhydrotic were not truly devoid of sweat glands.[12] Clouston in 1939 and Lowry et al. in 1966 described ED as a genetic entity.[13] Autosomal dominant disorder. Hydrotic ED is also known as Clouston’s syndrome.[11] ED is thought to occur in approximately 1 of 1,00,000 live births with a mortality rate of 28% in males up to 3 years of age.[1,14,15] They represent a large and complex group of diseases comprising more than 170 different clinical conditions.[2,15,16] There are two major types of ED depending on the number and functionality of the sweat glands; Hypohydrotic and Hydrotic.[15,17] Hypohydrotic type, also called as anhydrotic type, is the most common ED (80%) and is often inherited as an X-linked disorder (XLEDA).

[14] It is characterized by the classical triad of hypodontia, hypohidrosis and hypotrichosis with characteristic dysmorphic facial features.[10] In this type, the sweat glands are either absent or significantly reduced in number. It is also termed as Christ-Siemens-Tauraine syndrome.[10,15] The hydrotic form usually has normal sweat glands and the condition is inherited as autosomal dominant. This form also affects teeth, nails and hair. But the hereditary patterns and nail and sweat gland manifestations tend to differ from hypohydrotic type. It is termed Drug_discovery as Clouston’s syndrome.

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