Childhood-onset autoimmune cytopenia as the presenting feature of biallelic ACP5 mutations.

Childhood-onset chronic and refractory cytopenias are rare and may be genetic in etiology. We report three pediatric cases of severe autoimmune thrombocytopenia or anemia associated with growth retardation and spastic diplegia with intracranial calcification. The identification of platyspondyly and metaphyseal lesions suggested a potential diagnosis of spondyloenchondrodysplasia (SPENCD), which was confirmed with the identification of biallelic ACP5 mutations. Two patients demonstrated elevated serum interferon alpha levels. Our report highlights ACP5-associated disease as a cause of childhood-onset autoimmune cytopenia, particularly combined with growth retardation and/or spasticity. Furthermore, a role for type I interferon in the pathogenesis of autoimmune cytopenias is supported.