Significant Hair Regrowth With 5% Topical Minoxidil in a Child With Marie Unna Hereditary Hypotrichosis Caused by a Recurrent HRURF Variant

A 4-year-old girl with Marie Unna hereditary hypotrichosis (MUHH) showed significant hair regrowth after using 5% topical minoxidil. Initially, her hair was sparse and never exceeded 5 cm in length. After 12 weeks of minoxidil treatment, her hair density improved without adverse effects, and by 12 weeks post-resumption of treatment, her hair length exceeded 10 cm. This case suggests that 5% topical minoxidil may be effective in improving hair density in patients with MUHH, supporting its potential use in rare hereditary alopecias. The study highlights the importance of early intervention and individualized treatment approaches for congenital, genetically driven hair loss.