schimke immuno osseous dysplasia is a rare autosomal recessive multisystem disorder with the main clinical features of disproportionate growth deficiency defective cellular immunity and progressive renal disease it is caused by mutations of smarcal1 a gene encoding a putative chromatin remodeling protein of unknown function because a detailed description of the clinical features is an essential first step in elucidating the function of smarcal1 we present the first detailed anthropometric data for schimke immuno osseous dysplasia patients by comprehensive anthropometric examination 28 parameters of 8 patients 3 females with the typical findings of schimke immuno osseous dysplasia mean age 14 8 years range 4 9 30 5 years and 304 patients 117 females with congenital and hereditary chronic kidney disease mean age 10 7 4 8 years range 3 21 8 years we show that schimke immuno osseous dysplasia patients differ significantly from those with other forms of chronic kidney disease z scores were calculated with reference limits derived from 5155 healthy children 2591 females aged 3 to 18 years the key finding was that in the latter group median leg length was significantly more reduced than sitting height whereas in schimke immuno osseous dysplasia patients the reduction of sitting height was significantly more pronounced than for leg length therefore the ratio of sitting height leg length might be a simple tool for the clinician to distinguish schimke immuno osseous dysplasia from other chronic kidney disease patients schimke immuno osseous dysplasia is very likely if this ratio is 0 83 however other forms of chronic kidney disease have to be discussed in case of a ratio 1 01.