Lumbar spondylolysis: A report of four cases from two generations of a family.

Spondylolysis is a major cause of back pain in children and adolescents. The prevalence of spondylolysis depends on the sex, race, and congenital abnormality. These biases suggest hereditary predisposition as an etiology of spondylolysis. However, no conclusive evidence still exists regarding the inheritance for spondylolysis. Herein, we report rare cases with familial occurrence of lumbar spondylolysis. In two generations of a Japanese family, three brothers including identical twins complained of back pain related to sports activities. Clinical, radiographic, and computed tomographic examinations identified spondylolysis at L4 and L5 in all these boys. The father experienced long-term back pain and had spondylolisthesis at L4-L5 and healed spondylolysis at L5. The daughter and mother did not show any lumbar spondylolysis. The frequent development of spondylolysis at L4, a rarely affected segment, in four of six family members (66.7%) support that lumbar spondylolysis has an underlying genetic etiology, primarily autosomal dominant inheritance.