IGFBP1 and obesity due to melanocortin 4 receptor deficiency: Rahman et al. applied a bead-based multiplex immunoassay to measure plasma levels of IGFBP1, IGFBP3, and IGFBP7 in a cohort of 420 adolescents aged 11–14 years, identifying IGFBP1 as a sensitive biomarker of obesity-related metabolic complications [55].