Immuno-osseous dysplasia

Immuno-osseous dysplasia (also known as Schimke immuno-osseous dysplasia or Schimke type immunoosseous dysplasia, SIOD) is a rare multisystem disorder characterized by the combination of skeletal dysplasia and immune deficiency. The condition is caused by mutations in the SMARCAL1 gene, which encodes a chromatin remodeling protein involved in DNA repair and replication. The disease primarily affects the skeletal, immune, and renal systems. Key clinical features include spondyloepiphyseal dysplasia resulting in disproportionate short stature with a short trunk, T-cell immunodeficiency leading to recurrent and often life-threatening infections, and progressive steroid-resistant nephrotic syndrome that frequently advances to end-stage renal disease. Additional features may include hyperpigmented macules on the skin, cerebral ischemic events, hypothyroidism, and bone marrow failure. Facial features can include a broad nasal bridge and a triangular face. The severity of the disease is variable, ranging from a severe infantile-onset form with early mortality to a milder form with later onset and longer survival. Treatment is primarily supportive and symptomatic, including renal transplantation for end-stage kidney disease, immunoglobulin replacement therapy, prophylactic antibiotics for immune deficiency, and growth hormone therapy (though response is typically poor). Hematopoietic stem cell transplantation has been attempted to address the immune deficiency, with variable outcomes. Prognosis in the severe form is often poor, with many patients succumbing to infections or renal failure in childhood or early adulthood.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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