Renal agenesis is a complete absence of one (unilateral) or both (bilateral) kidneys, whereas in renal aplasia the kidney has failed

1: Hage D, Iwanaga J, Dumont AS, Tubbs RS. Caudal regression syndrome and a pelvic kidney: case report. Anat Cell Biol. 2020 Dec 31;53(4):509-511. doi: 10.5115/acb.20.057. PMID: 32647073; PMCID: PMC7769103.

2: Shaheen R, Mark P, Prevost CT, AlKindi A, Alhag A, Estwani F, Al-Sheddi T, Alobeid E, Alenazi MM, Ewida N, Ibrahim N, Hashem M, Abdulwahab F, Bryant EM, Spinelli E, Millichap J, Barnett SS, Kearney HM, Accogli A, Scala M, Capra V, Nigro V, Fu D, Alkuraya FS. Biallelic variants in CTU2 cause DREAM-PL syndrome and impair thiolation of tRNA wobble U34. Hum Mutat. 2019 Nov;40(11):2108-2120. doi: 10.1002/humu.23870. Epub 2019 Jul 29. Erratum in: Hum Mutat. 2021 Feb;42(2):219. PMID: 31301155.

3: Maeda H, Go H, Sakuma J, Imamura T, Sato M, Momoi N, Hosoya M. Myelomeningocele with Unilateral Right Renal Agenesis: A Case Report. AJP Rep. 2018 Jan;8(1):e1-e3. doi: 10.1055/s-0037-1615818. Epub 2018 Jan 9. PMID: 29321944; PMCID: PMC5760242.