Response to steroid therapy in autism secondary to autoimmune lymphoproliferative syndrome

We report a child who developed autoimmune lymphoproliferative syndrome (AL PS) secondary to a heterozygous dominant negative mutation in the death dom ain of the Fas receptor. Previously developmentally normal, he had symptoms of autism with rapid regression in developmental milestones coincident wit h the onset of lymphoproliferation and autoimmune hemolytic anemia. Low-dos e steroid therapy induced early and complete remission in the ALPS phenotyp e. There was subjective improvement, followed by objective improvement in s peech and developmental milestones. We propose that autism may be part of t he autoimmune disease spectrum of ALPS in this child, and this case represe nts a novel manifestation and target organ involvement in this disease.