B9D1 and cerebellar ataxia: In 2015, a genetic analysis performed of a 22-year-old patient with MTS, OMA, hypotonia, ataxia, congenital clubfoot, and dysphasia identified two variants in B9D1 predicted to be damaging: a maternally inherited nonsense mutation (c.493C>T; p.Gln165*) and a de novo missense mutation (c.151T>C; p.Ser51Pro) [24].