Last reviewed: May 12, 2026 Last updated: May 12, 2026

Written by: Jay Hastings , CEO of PlexusDx

Jay Hastings is the CEO of PlexusDx, a precision health company focused on genetic testing, blood biomarker insights, and personalized wellness recommendations. He has more than 20 years of experience across healthcare innovation, genomics, laboratory operations, healthcare investing, and strategic finance. His work has included scaling healthcare startups, leading CLIA lab integrations, and helping expand consumer access to precision health tools.

Medically reviewed by: Jayden Lee, PharmD, EMBA

Jayden Lee, PharmD, EMBA, is the PlexusDx Medical Science Liaison with a PharmD and MBA specializing in pharmacogenomics and clinical product development, with a proven ability to bridge the gap between genomic research and practical patient outcomes. Dr. Lee has more than 10 years of professional experience in clinical pharmacy, academia, and research.

This article is part of the PlexusDx Education Hub — your resource for evidence-based, DNA-driven health insight. Browse all Genetics & Health education.

Ankylosing spondylitis (AS) is a form of inflammatory arthritis that primarily affects the spine and the sacroiliac joints where the spine meets the pelvis. It causes chronic back pain and stiffness that is typically worse in the morning or after rest and eases with movement — a pattern that distinguishes it from ordinary mechanical back pain. Of all the rheumatic diseases, AS has one of the strongest genetic signatures, which is why understanding the genes involved is so central to understanding the condition.

What happens in ankylosing spondylitis

In AS, the immune system drives inflammation at the entheses — the sites where ligaments and tendons attach to bone — especially along the spine. Over time, chronic inflammation can prompt new bone formation, gradually reducing spinal flexibility and, in some people, fusing vertebrae. Symptoms usually begin in late adolescence or early adulthood. This is a description of the disease process for education only; diagnosis and management are the domain of a rheumatologist, not a genetic report.

HLA-B27: the strongest genetic link

The gene most associated with AS is HLA-B27, part of the human leukocyte antigen system that helps the immune system distinguish self from foreign invaders. The large majority of people with AS carry HLA-B27, and carrying it substantially raises risk. Yet the relationship is not deterministic: most people who carry HLA-B27 never develop AS at all. The gene shapes how immune cells present protein fragments, which is thought to contribute to the misdirected inflammation seen in the disease.

Beyond HLA-B27: ERAP1 and the IL-23/IL-17 pathway

HLA-B27 is necessary background for many cases but not the whole story. The gene ERAP1 trims protein fragments before HLA molecules present them, and certain ERAP1 variants appear to interact specifically with HLA-B27 to modify risk. Meanwhile, variants in IL23R and related genes point to the IL-23/IL-17 immune signaling pathway, a driver of the inflammation that characterizes AS. This pathway has become a major focus of research into the biology behind the disease.

Why not everyone with HLA-B27 develops AS

Because most HLA-B27 carriers never develop AS, genetics clearly sets the stage without writing the script. Additional genes, sex, gut microbiome differences, and environmental triggers all appear to influence whether inflammation actually takes hold. This incomplete penetrance is why a positive HLA-B27 result is meaningful in the context of symptoms but is not, by itself, a diagnosis. Clinical evaluation and imaging remain essential.

Understanding your genetics and working with a rheumatologist

If you have persistent inflammatory back pain — especially with morning stiffness that improves with activity — a rheumatologist can evaluate you using symptom history, physical examination, imaging of the sacroiliac joints, and blood tests that may include HLA-B27 typing and inflammatory markers. Management is individualized and clinician-led, spanning exercise and physical therapy, posture care, and medications a specialist prescribes. Genetic education can inform these conversations but never replaces professional diagnosis or treatment.

What genetic insight can and can’t do

A consumer genetic report does not diagnose ankylosing spondylitis, confirm HLA-B27 clinical status, or replace a rheumatologist. What pathway-level insight can do is help you understand the inflammatory and immune biology involved. The Precision Peptide Genetic Test analyzes 14 pathways, 49 peptides, 150+ genetic insights, including immune and inflammatory pathways relevant to genes like those discussed here. Treat it as educational context to bring to your provider — genetics as a guide, not a guarantee.

Frequently Asked Questions

What gene is most linked to ankylosing spondylitis?

HLA-B27 is by far the strongest genetic link. Most people diagnosed with ankylosing spondylitis carry it, and carrying it raises risk substantially. However, most HLA-B27 carriers never develop the condition, so the gene sets the stage without determining who actually develops the disease.

If I carry HLA-B27, will I get ankylosing spondylitis?

Almost certainly not just from the gene. Most HLA-B27 carriers never develop ankylosing spondylitis. Additional genes like ERAP1 and IL23R, sex, gut microbiome, and environmental factors all influence risk. A positive result matters only in the context of symptoms evaluated by a rheumatologist.

Can a genetic test diagnose ankylosing spondylitis?

No. Diagnosis requires a rheumatologist who combines symptom history, physical examination, imaging of the sacroiliac joints, and blood tests. A consumer genetic test offers pathway-level educational context about immune and inflammatory biology, not a diagnosis, treatment plan, or clinical HLA-B27 status.

What helps manage spine stiffness in ankylosing spondylitis?

Management is individualized and clinician-led. Rheumatologists commonly emphasize regular exercise and physical therapy, posture care, and medications they prescribe based on your case. Staying active is especially important for maintaining spinal mobility. Always follow a qualified provider’s guidance rather than self-managing.

Want pathway-level context on the immune and inflammatory genes researchers study? Take the Precision Peptide Genetic Test to explore 14 pathways, 49 peptides, 150+ genetic insights at the DNA level. PlexusDx tells you about your biology — your provider helps you decide what to do with it.

Disclaimer: The Precision Peptide Genetic Test analyzes how your genes influence peptide-related biological pathways. It does not recommend, prescribe, or determine which peptides you should use, and it does not diagnose, treat, cure, prevent, or manage any disease or condition. Genetics is a guide, not a guarantee. Consult a qualified healthcare provider before beginning any peptide protocol or making changes to your health plan.

Medical and Editorial Standards

Medical review process: This article was reviewed for medical accuracy, scientific clarity, evidence alignment, and appropriate discussion of genetics, medications, supplements, biomarkers, and health-related claims.

Sources and evidence: PlexusDx educational content is developed using peer-reviewed research, clinical literature, reputable medical references, and, where applicable, public health or regulatory guidance. References are included at the end of the article when scientific, medical, or health-related claims are discussed.

Commercial transparency: PlexusDx offers genetic testing, blood biomarker testing, personalized supplement recommendations, and related precision wellness services. Product mentions are intended to help readers understand available options and should not be interpreted as medical advice.

Important disclaimer: PlexusDx educational content is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about medications, supplements, genetic testing, lab testing, or health-related care.

This article is part of the PlexusDx Education Hub. Browse all Genetics & Health education.