[1] NIH, Ctr Clin, Clin Res Ctr, Bethesda, MD 20892 USA
[2] Eunice Kennedy Shriver Natl Inst Child Hlth & Hum, NIH, Bethesda, MD 20892 USA
[3] Hosp Ninos Dr Ricardo Gutierrez, Ctr Invest Endocrinol, Div Endocrinol, Buenos Aires, DF, Argentina
[4] Childrens Hosp Los Angeles, Los Angeles, CA 90027 USA