Some ectodermal dysplasias are here classified as congenital disorders characterized by abnormal development in 2 or more ectodermal structures (hair, nails, teeth, and sweat glands) without other systemic findings.
Hypohidrotic, or anhidrotic, ectodermal dysplasia is characterized ... Some ectodermal dysplasias are here classified as congenital disorders characterized by abnormal development in 2 or more ectodermal structures (hair, nails, teeth, and sweat glands) without other systemic findings. Hypohidrotic, or anhidrotic, ectodermal dysplasia is characterized by a triad of signs comprising sparse hair (hypotrichosis), abnormal or missing teeth (anodontia or hypodontia), and inability to sweat (anhidrosis or hypohidrosis). Typical clinical manifestations also include dryness of the skin, eyes, airways, and mucous membranes presumably due to the defective development of several exocrine glands. Hypohidrotic ectodermal dysplasia can be associated with dysmorphic features (forehead bumps, rings under the eyes, everted nose, and prominent lips) and occasionally with absent nipples (summary by Cluzeau et al., 2011). For a discussion of genetic heterogeneity of hypohidrotic/anhidrotic ectodermal dysplasia, see 305100.
Munoz et al. (1997) identified 5 families with possible autosomal recessive HED on the basis of the presence of severely affected females and unaffected parents in single sibships and in highly consanguineous families with multiple affected family members. ... Munoz et al. (1997) identified 5 families with possible autosomal recessive HED on the basis of the presence of severely affected females and unaffected parents in single sibships and in highly consanguineous families with multiple affected family members. The disorder was excluded from the EDA locus on the X chromosome (305100) by the lack of its cosegregation with polymorphic markers flanking the EDA locus in 3 of the 5 families. No mutations of the EDA gene (300451) were detected by SSCP analysis in the 2 families not excluded by haplotype analysis. The appearance of affected males and females in autosomal recessive HED was clinically indistinguishable from that seen in males with X-linked HED. The findings of equally affected males and females in single sibships, as well as the presence of consanguinity, supported an autosomal recessive mode of inheritance. The fact that phenotypically identical types of HED can be caused by mutations at both X-linked and autosomal loci is analogous to the situation in the mouse, where indistinguishable phenotypes are produced by mutations at both X-linked ('Tabby') and autosomal ('crinkled' and 'downless') loci.