ACP5 and autoimmune disease: Furthermore, Lausch et al., [8] described a 10 year old patient with a p.Gly215Arg homozygous ACP5 mutation in whom the only extra-skeletal feature was of intracranial calcification, i.e. a patient with ‘SPENCD’, whilst, we and Lausch et al., [8] observed the same mutation in three unrelated patients, from two families, all of whom had autoimmune disease.