The world's first genetically enhanced humans are already here. Alternatively you could call them the first true Transhumans or one may go as far as to call them proto-beings for Homo sapiens consectetur.
There are at least 2 humans who have enhanced their Genome via gene therapy
Brian Hanley founder of Butterfly Sciences injected the GHRH plasmid gene to increase Growth hormone–releasing hormone levels.
Results: Increased GHRH levels.
Elizabeth Parrish CEO of Bioviva injected a gene that acts as a myostatin inhibitor and another that acts as a Telomerase reverse transcriptase inducer.
Results: SpectraCell Laboratories indicated that her leukocyte telomeres had lengthened by approximately 20 years, from 6.71kb to 7.33kb. MRI scans taken before and after depict a slight increase in muscle size in conjunction with a noticeable reduction in muscle fat content. C-Reactive Protein, a potent marker of systemic inflammation, was notably decreased from 1.6 mg/dL to <0.2 mg/dL
Sources:
https://www.technologyreview.com/s/603217/one-mans-quest-to-hack-his-own-genes/