Familial history, age and smoking are important risk factors for disc degeneration disease in Arabic pedigrees

The present study used computed tomography imaging to evaluate the extent and pattern of the intergenerational transmission of spinal disc degeneration disease (DDD) in complex pedigrees. Contribution of a number of the potential covariates was also studied using univariate and multivariate logistic regression analysis, as well as two types of complex segregation analysis models. Among 161 individuals studied, DDD was diagnosed in 60 individuals. The number of protruded discs varied from 1 to 4, mostly in lumbar or lumbosacral regions. The average age at onset of the disease was similar for both women (36.0 years) and men (34.8 years). The proportion of the individuals affected by the DDD status of their parents ranged from 10% in families of two healthy parents to 55.5% of two affected parents (p < 0.01). The results of the logistic regression analyses and complex segregation analysis were qualitatively the same: DDD status of parents, age and smoking were the main risk factors for disc herniation in the Arabic families we examined. All analyses showed a predominating role of the family history as a risk factor for DDD in offsprings. It showed, for example, four times higher risk at age 50 for individuals with two affected parents vs. those who have two non-affected parents. However, the results of models-fitting genetic analysis, did not confirm a monogenic Mendelian pattern of inheritance.