Agenesis of the Corpus Callosum (ACC) can result in multiple neurological deficits including social and behavioural issues. However, the underlying aetiology, clinical co-morbidity and the contributing risk factors remain elusive, resulting in inaccurate prognosis and delayed therapy. The main objective of this study was to comprehensively describe the epidemiology and clinical co-morbidity associated with patients diagnosed with ACC. The secondary objective was to identify the factors that contribute towards increased risk for ACC. For this, we analysed 22 years (1998–2020) of clinical data across the whole of Wales, UK collected through the Congenital Anomaly Register & Information Service (CARIS) and Public Health Wales (PHW). Our results demonstrate that complete ACC (84.1%) was the prevalent subtype, in comparison to partial ACC. Further, ventriculomegaly/hydrocephalus (26.37%) and ventricular septal defect (21.92%) were identified to be the most prevalent neural malformation (NM) and congenital heart disorder (CHD) in our cohort. Although 12.7% of subjects with ACC had both an NM and CHD, we found no significant association between them (χ2(1,n= 220) = 3.84,p= 0.33). We found socioeconomic deprivation and increased maternal age contributed towards an increased risk for ACC. To the best of our knowledge, this study for the first time defines the clinical phenotypes and the factors that contribute to ACC within the Welsh population. These findings will be of value to both patients and healthcare professionals, who may take preventative or remedial measures.