It was first characterized in 1965, in Oslo, by prof. Roar Theodor Bjørnstad (1908–2002).
It has been mapped to BCS1L. Hearing disabilities related to Björnstad syndrome are congenital, and the severity of the deafness varies from person to person. Pili torti is recognized in early childhood and is characterised by twisted hair shafts and brittle hair.The hearing loss usually becomes evident very early in life, often in the first year. It is caused by mutations in the BCS1L gene which also cause GRACILE syndrome.