This rare condition, also known as “spun-glass hair” and cheveux incoiffables, normally arises between the ages of 3 months and 12 years. It’s well named — patients develop dry, wiry, frizzy hair that’s impossible to comb. The cause is genetic, and the symptoms tend to resolve by adolescence.

The condition is also known as Struwwelpeter syndrome, after the 19th-century German children’s book Der Struwwelpeter, whose title character is “Shock-Headed Peter.”