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SOX9 gene

Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

SOX9 gene

The SOX9 gene encodes a transcription factor that is critical for skeletal development and sex determination during embryonic growth.

Normal Function

The SOX9 gene provides instructions for making a protein that acts as a transcription factor. By binding to specific regions of DNA, the SOX9 protein regulates the activity of other genes, particularly those responsible for skeletal development and the determination of sex before birth.

Health Conditions Related to Genetic Changes

Campomelic dysplasia

More than 70 mutations in the SOX9 gene have been linked to campomelic dysplasia, a life-threatening disorder affecting skeletal development and sex determination. Genetic changes include:

  • Gene mutations: Most cases are caused by mutations within the gene that prevent the production of the SOX9 protein or impair its function.
  • Chromosome abnormalities: About 5 percent of cases involve abnormalities near the SOX9 gene that disrupt enhancers—regions of DNA that regulate gene activity.

Individuals with milder forms of the condition are more likely to have chromosome abnormalities near the gene rather than mutations within the gene itself.

Isolated Pierre Robin sequence

Genetic changes near the SOX9 gene can cause isolated Pierre Robin sequence. This condition is characterized by:

  • A small lower jaw (micrognathia).
  • A tongue placed further back than normal (glossoptosis), which can block airways.
  • An opening in the roof of the mouth (cleft palate).

These changes disrupt enhancer regions that regulate SOX9 activity during jaw development, leading to the underdevelopment of the lower jaw and subsequent airway and palate issues.

Other conditions

The SOX9 gene is also associated with:

  • 46,XX testicular difference of sex development
  • Swyer syndrome

Frequently Asked Questions

Yes. Prenatal carrier testing or pre‑implantation genetic diagnosis (PGD) can identify pathogenic SOX9 mutations or nearby enhancer deletions in you or your partner. Discuss testing options with a medical geneticist or a reproductive specialist early in the planning process so results can inform pregnancy decisions or IVF‑PGD strategies.
detailed fetal anatomy scan that notes skeletal anomalies should be followed by targeted molecular testing. This can be done via chorionic villus sampling (10‑12 weeks) or amniocentesis (15‑18 weeks) to sequence the SOX9 coding region and assess the surrounding regulatory region for deletions or duplications. Results guide prognosis and perinatal care planning.
Enhancer alterations near SOX9 can reduce its activity during jaw development, causing micrognathia, glossoptosis, and cleft palate. Most children with isolated Pierre Robin sequence have normal growth, cognition, and endocrine function. Management focuses on airway support, feeding assistance, and surgical repair of the palate. Long‑term follow‑up includes monitoring speech development and orthodontic needs; there is typically no increased risk of liver or immune problems linked to SOX9.
First, coordinate care with a multidisciplinary team: pediatric endocrinology, genetics, urology, psychology, and a surgeon experienced in DSD. Hormone evaluation will determine the need for testosterone or estrogen therapy to support appropriate pubertal development. Discuss options for gonadal surgery or preservation based on fertility goals and cancer risk. Provide age‑appropriate counseling and peer support to address gender identity, body image, and psychosocial wellbeing. Regular follow‑up is essential to monitor growth, bone health, and mental health.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.