However, like the term “recurrent infections,” most reports fail to provide a clear definition of the term “developmental delay.” Since some patients living with CLD display normal intelligence prior to metreleptin substitution (formal IQ testing for 1 patient at our center was 116; data not published), leptin deficiency itself might not be the cause of this delay. The gene discussed is LEP; the disease is congenital secretory chloride diarrhea 1.