Different growth patterns in two siblings with Schimke immuno-osseous-dysplasia

Schimke immuno-osseous-dysplasia (SIOD) is an autosomal recessive systemic disease due to pathogenic variants in SMARCAL1. Manifestations include nephrotic syndrome (NS), kidney failure, T-cell dysfunction, vaso-occlusive disease, and disproportionate short stature, a general feature of this disease. Here, we present a markedly different growth pattern in two brothers with SIOD sharing the same homozygous R561C missense variant. The index patient presented at the age of 11 years with NS and severely disproportionate short stature, followed by kidney failure at the age of 16, and severely reduced adult height (z-score - 8.0). In contrast, the younger brother showed normal growth until the age of 8 years. Mild proteinuria was noted at the age of 4.5, followed by NS at 9.5 years, kidney failure at 11 years, progressive disproportionate stature, and reduced adult height (z-score - 4.5). Both brothers had comparable disproportion in adulthood (sitting height index z-score - 0.88 and - 1.44, respectively).