Biallelic mutations in the BiP co-chaperone SIL1 cause Marinesco–Sjögren syndrome (MSS) in humans, a condition characterized by cataracts, early-onset cerebellar ataxia, cognitive deficits, short stature, and progressive vacuolar myopathy (Anttonen et al., 2005; Senderek et al., 2005; Krieger et al., 2013). The gene discussed is HSPA5; the disease is aceruloplasminemia.