Schimke immuno-osseous dysplasia

Schimke immuno-osseous dysplasia (SIOD), also known as Schimke syndrome or spondyloepiphyseal dysplasia with nephrotic syndrome, is a rare multisystem autosomal recessive disorder caused by mutations in the SMARCAL1 gene, which encodes a chromatin remodeling protein. The disease primarily affects the skeletal system, immune system, and kidneys. It is characterized by spondyloepiphyseal dysplasia resulting in disproportionate short stature with a short neck and trunk, progressive steroid-resistant nephrotic syndrome leading to end-stage renal disease, and T-cell immunodeficiency that predisposes affected individuals to recurrent and often life-threatening infections. The clinical spectrum of SIOD ranges from a severe form with onset in infancy and early death to a milder form with later onset and longer survival. Additional features may include cerebral ischemic events (stroke-like episodes), hyperpigmented macules on the skin, abnormal dentition, hypothyroidism, and bone marrow failure. Facial features may include a broad, depressed nasal bridge and a triangular face. Renal disease typically manifests as focal segmental glomerulosclerosis. There is no cure for Schimke immuno-osseous dysplasia. Treatment is supportive and directed at managing specific symptoms. Kidney transplantation is often necessary for end-stage renal disease, though recurrence of nephrotic syndrome in the transplanted kidney is uncommon. Bone marrow or hematopoietic stem cell transplantation has been attempted to address the immunodeficiency, with variable outcomes. Prophylactic antibiotics and immunoglobulin replacement therapy may be used to manage the immune deficiency. Prognosis varies depending on disease severity, with the severe form often resulting in death in childhood due to infections, stroke, or renal failure.

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