Evidence of an inherited predisposition for cervical spondylotic myelopathy.

STUDY DESIGN: A retrospective, population-based study cross-referencing a genealogic database of over 2 million Utah residents with 10 years of clinical diagnosis data from a large tertiary hospital.

OBJECTIVE: The objective of this study is to determine the presence or absence of an inherited predisposition to the development of cervical spondylotic myelopathy (CSM).

SUMMARY OF BACKGROUND DATA: A genetic predisposition for the development of cervical spondylosis has been discussed in the literature with low-quality evidence. Families with a high incidence of disease or early-onset disease in monozygotic twins have both been reported. However, these suggestions of an inherited predisposition for disease have never been rigorously studied. The purpose of this study is to determine a genetic predisposition among patients diagnosed with CSM.

METHODS: The Utah Population Database combines health and genealogic data on over 2 million Utah residents. International Classification of Diseases, Ninth Revision (ICD-9) codes were used to identify 486 patients in the database with a diagnosis of CSM (ICD-9 code 721.1). The hypothesis of excessive familial clustering was tested using the Genealogical Index of Familiality (GIF), and relative risks (RRs) in relatives were estimated by comparing rates of disease in relatives with rates estimated in the relatives of five matched controls for each case. This methodology has been previously reported and validated for other disease conditions but not for CSM.

RESULTS: The GIF analysis for patients with CSM showed significant excess relatedness for disease (P < 0.001). RRs were significantly elevated in both first- (RR = 5.21, CI = 2.1-13.2, P < 0.001) and third-degree relatives (RR = 1.95, CI = 1.04-3.7, P < 0.05).

CONCLUSION: Excess relatedness of cases and significantly elevated RRs to both close and distant relatives supports an inherited predisposition to CSM.