The nephrotic syndrome occurs infrequently prior to the second year of life. When nephrosis does develop during the first year, the course differs from that of older children with nephrosis, being characterized by an extremely poor prognosis and an almost complete refractoriness to therapy. Despite its low incidence, infantile nephrosis is important, not only because of the severity of the disorder itself but also because the occurrence of nephrosis in this age group raises questions regarding the etiology of the disease.
Since 1952, we have studied 12 patients who developed nephrosis during the first year of life. These cases illustrate the characteristic clinical and laboratory features of the disease, the difficulties in management, and the inordinately high mortality rate of infantile nephrosis. The purpose of this paper is to present a clinical and laboratory analysis of these cases, together with morphologic observations obtained by kidney biopsy and autopsy material, studied