Symptomatic lumbar disc disease caused by degeneration of the discs of the lower spine could be inherited, indicates a new study.
"The results of this study provide evidence based on a population of more than 2 million people, indicating that there likely is a genetic component in the development of this disease. Additionally, the factors that differentiate a symptomatic disc from a non-painful disc may also be affected by genetics," said study author Alpesh A. Patel, FACS, assistant professor of orthopaedic surgery at the University of Utah School of Medicine.
To measure how closely patients were related, the researchers used the Genealogical Index of Familiaity, which compares the average relatedness of affected individuals with expected relatedness in the general population. Relatedness is measured by generations or degrees:
first-degree relatives (or immediate family) including parents, offspring and siblings;
second-degree including grandchildren, grandparents, uncles, aunts, nieces, nephews, and half-siblings; and
third-degree comprising great-grandchildren, great-grandparents, great-aunts and great-uncles, grandnieces and grandnephews and first cousins.
In this study, only patients with at least three generations of genealogical data in the database were included.
The researchers also determined and calculated the Relative Risk (RR) for relatives. This measure defines the risk of lumbar disc disease among family members of patients compared to individuals without disease. Important Findings:
Individuals with lumbar disc disease were more likely to have family members with disc disease.
Relative risk for lumbar disc disease was significantly elevated in both close and distant relatives.
The combination of the two findings, given the large patient population, strongly supports a genetic basis to symptomatic lumbar disc disease.
"Although excess risk in the immediate family might indicate evidence of a genetic contribution, it could also simply indicate shared environment risks or household exposure that may be contributing to the disease," Patel noted.
The study has been published in the Journal of Bone and Joint Surgery (JBJS).