Schimke immunoosseous dysplasia (SIOD) is characterized by spondyloepiphyseal dysplasia (SED) resulting in short stature, nephropathy, and T-cell deficiency. Radiographic manifestations of SED include ovoid and mildly flattened vertebral bodies, small ilia with shallow dysplastic acetabular fossae, and small deformed capital femoral epiphyses. Nearly all affected individuals have progressive steroid-resistant nephropathy, usually developing within five years of the diagnosis of growth failure and terminating with end-stage renal disease. The majority of tested individuals have T-cell deficiency and an associated risk for opportunistic infection, a common cause of death. SIOD involves a spectrum that ranges from an infantile or severe early-onset form with a greater risk of death during childhood to a juvenile or milder later-onset form with likely survival into adulthood if renal disease is appropriately treated.

Autosomal dominant severe congenital neutropenia-8 (SCN8) is a pleiotropic disorder with the consistent feature of decreased neutrophils associated with recurrent bacterial infections apparent from early infancy. Other hematologic parameters are usually normal, although some patients may have mild anemia. Bone marrow examination shows hypocellularity with arrested maturation of the granulocyte lineage at the level of promyelocytes or myeloblasts. Treatment with granulocyte colony-stimulating factor (GCSF; 138970) is usually ineffective or only partially effective, whereas hematopoietic bone marrow transplantation is effective. A subset of patients have additional features, including exocrine pancreatic insufficiency, which resembles Shwachman-Diamond syndrome (see SDS1, 260400), and/or neurologic deficits, including developmental delay, impaired intellectual development, speech delay, and/or autistic features (summary by Carapito et al., 2017 and Bellanne-Chantelot et al., 2018). For discussion of genetic heterogeneity of severe congenital neutropenia, see SCN1 (202700).