Researchers from the RIKEN Center for Integrative Medical Sciences in Japan have identified the first gene to be associated with adolescent idiopathic scoliosis (also called AIS) across Asian and Caucasian populations. The gene is involved in the growth and development of the spine during childhood.
Their study is published today in the journal Nature Genetics.
AIS is the most common pediatric skeletal disease, affecting approximately 2% of school-age children. The causes of scoliosis remain largely unknown and brace treatment and surgery are the only treatment options. However, many clinical and genetic studies suggest a contribution of genetic factors.
To understand the causes and development of scoliosis, Dr Ikuyo Kou, Dr Shiro Ikegawa and their team have tried to identify genes that are associated with a susceptibility to develop the condition.
By studying the genome of 1,819 Japanese individuals suffering from scoliosis and comparing it to 25,939 Japanese individuals, the team identified a gene associated with a susceptibility to develop scoliosis on chromosome 6. The association was replicated in Han Chinese and Caucasian populations.
The researchers show that the susceptibility gene, GPR126, is highly expressed in cartilage and that suppression of this gene leads to delayed growth and bone tissue formation in the developing spine. GPR126 is also known to play a role in human height and trunk length.
Scoliosis is a condition in which the spine- in addition to the normal front to back curvature- has an abnormal side- to- side “S- ” or “C”- shaped curvature. The spine is also rotated or twisted, pulling the ribs along with it to form a multidimensional curve.
The Scoliosis Research Society defines scoliosis as a curvature of the spine measuring 10 degrees or greater on x- ray. The condition isn’t rare. It mainly affects girls- many of whom have mild forms of scoliosis, are never even aware of it, and never need treatment.
Three to five children out of every 1,000 develop spinal curves that are considered large enough to require treatment. Idiopathic scoliosis does tend to run in families, although no one genetic link has been confirmed.
Scoliosis occurs, and is treated, as three main types:
idiopathic scoliosis: the most common form, with no definite cause, mainly affecting adolescent girls, but existing in three age groups:
adolescent idiopathic scoliosis
juvenile idiopathic scoliosis
infantile (early- onset) idiopathic scoliosis
neuromuscular scoliosis: associated with a neuromuscular condition such as cerebral palsy, myopathy or spina bifida
congenital scoliosis: present at birth, caused by a failure of the vertebrae to form normally- the least common form
About idiopathic scoliosis
“Idiopathic” simply means that there is no definite cause for a given disease or condition. Idiopathic scoliosis isa condition in which the child’s spine- in addition to the normal front to back curvature- has an abnormal side- to- side “S- ” or “C”- shaped curvature. The spine is also rotated or twisted, pulling the ribs along with it to form a multidimensional curve.
Idiopathic scoliosis is the most common form of the condition, and it mainly affects adolescent girls.
“Our finding suggest the interesting possibility that GPR126 may affect both AIS susceptibility and height through abnormal spinal development and growth,” explain the authors.
“Further functional studies are necessary to elucidate how alterations in GPR126 increase the risk of AIS in humans,” they conclude.
Idiopathic scoliosis Statistics
Frequency of scoliosis:
Scoliosis curves measuring at least 10° occur in 1.5% to 3.0% of the population
Curves exceeding 20° occur in 0.3% to 0.5% of the population
Curves exceeding 30° occcur in 0.2% to 0.3% of the population
Small spinal curves occur with similar frequency in boys and girls, but girls are more likely to have a progressively larger scoliotic curve that will require treatment.
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A picture and a copy of the paper are available on request.
Picture caption: Girl with adolescent idiopathic scoliosis (left) and posterior-anterior standing x-ray of spine (right).
“Genetic variants in GPR126 are associated with adolescent idiopathic scoliosis.” Kou et al. Nature Genetics 2013, DOI: 10.1038/ng.2639
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