The developmental and genetic etiology of most congenital vertebral malformation disorders remains unknown. The objective of this study was to evaluate and classify congenital vertebral defect cases into groupings based on developmental etiology for clinical genetic studies. This classification is intended to be distinct from but complementary to traditional groupings based on spinal curvature or progression. hi the first step of this analysis, the authors identified 84 cases of vertebral segmentation disorders by radiologic screening and prospectively recruited 39 of these patients into a clinical genetic study. Next, the authors quantified the extent of contiguous defects and organized cases by craniocaudal localization. Finally, the authors used available clinical association data to identify syndromic and nonsyndromic subcategories, and identified a high rate of orthopaedic and neurologic associations in nonsyndromic patients. This type of analysis has identified subgroups of patients with multiple, contiguous segmental defects and orthopaedic associations that are particularly suitable for further genetic analysis.