GH1 and isolated congenital growth hormone deficiency: This report aimed to reveal a novel homozygous large deletion of approximately 1.6 kb spanning the GH1 gene in a male patient who achieved the criteria for severe IGHD, presented with growth retardation (−4SD) at 4 months old, and due to novel mutations considered as the etiology, antibody production interfering with treatment, and various phenotypes and responses to treatment, more research is needed to improve the prognosis, management, quality of life, and provide methods with lower costs.