Pure hair and nail ectodermal dysplasia is characterized by the association of onychodystrophy and severe hypotrichosis, which is mainly limited to the scalp but may also affect the eyelashes and eyebrows. Less than 20 cases have been reported so far. The mode of transmission is autosomal dominant. The disease is MONDO_0019071 (pure hair and nail ectodermal dysplasia). Also known as: HNED, PHNED, hair-nail ectodermal dysplasia.