A 5-year-old boy was admitted to the hospital with failure to thrive since he was 2 years old, with weakness in his legs and a waddling gait. He has normal mental development. His parents are normal phenotypically and are unrelated. In analyzing his pedigree only a grandfather is described to have waddling gait. He has a normal craniofacial appearance but a disproportionate body with normal trunk and short extremities with height below the 3rd percentile. The diagnosis of pseudoachondroplasia was made on clinical, radiological and laboratory findings. He also had immune deficiency characterized by low T-lymphocyte populations and a low level of serum immunoglobulin A.