[Scoliosis].

Idiopathic scoliosis (crooked spine) can be a crippling disease in humans. A common form primarily affects adolescent girls. There is clear evidence that idiopathic scoliosis is inherited. However, in humans, the pattern of inheritance is not clear. Several years ago, Dr. L. W. Taylor of this department (Berkeley campus) developed an inbred strain of chickens in which up to 50 percent of the birds developed scoliosis. Subsequent research revealed a number of striking similarities between scoliosis in these birds and man. A more extensive study, with support from an Orthopaedic Research and Education grant and an NIH grant, is underway. Cooperating with the UCD Departments of Orthopaedics, Animal Science and Nutrition, we have found that, in the scoliotic strain, the first spinal curves are detected after birds reach four weeks of age, usually between the fifth and sixth weeks. As these birds mature, progressively more severe curves develop until spontaneous fusion of the thoracic vertebrae occurs. The incidence of curved spines in sexually mature adults is now about 55 percent and is more frequent in males than in females. Thus, in chickens as well as in humans, the homogametic sex is more prone to scoliosis. Our work also shows that abnormalities of growth and development of the spine are not the primary cause of scoliosis, nor is simple muscle imbalance involved.