Evaluation of Phenotypic and Genetic Properties in Male Subjects Affected By Hypohidrotic Ectodermal Dysplasia (ECP-012)

Inclusion Criteria: Subjects must meet all of the following criteria to be enrolled in this study. * Attending the 2012 Spanish Association for those Affected by Ectodermal Dysplasia Annual Reunion; * One year of age or greater; * Conform to one of the following requirements for providing informed consent/assent: * If more than 18 years of age, subjects must provide signed informed consent; * If less than 18 years of age and it is determined that the subject is capable of providing assent, both the assent of the subject and consent of the parent(s) or guardian of that subject must be granted. Under this condition, both parents of the subject should give their permission, unless 1 parent is deceased, unknown, incompetent, or not available; * If the subject is incapable of providing assent, the consent of the parent(s) or guardian of the subject must be granted. Under this condition, both parents should give their consent, unless 1 parent is deceased, unknown, incompetent, or not available. * Can provide documentation of genetic testing results positive for an EDA gene mutation /deletion; * As described in Section 3.2 above, subjects must meet one of the following criteria: * Documented diagnosis of XLHED confirmed via genetic testing; * Unaffected male controls. Exclusion Criteria: * Known hypersensitivity to pilocarpine or pilocarpine-like muscarinic agonists; * Presence of pacemakers; * Subjects who are not able or are not willing to comply with the procedures of this protocol; * Subjects with any major medical problem that will prevent them from participating in this study.