Monarch Disease Ontology identifier MONDO_0018631 (Marie Unna hereditary hypotrichosis) is a rare autosomal dominant hair loss disorder characterized by the absence or scarcity of scalp hair, eyebrows, and eyelashes at birth; coarse and wiry hair during childhood; and progressive hair loss beginning around puberty. Also known as: HR hypotrichosis, MUHH, Marie Unna congenital hypotrichosis, hypotrichosis caused by mutation in HR, hypotrichosis, Marie Unna type.