Spondylitis refers to as long term inflammation of one or more vertebrate. Also referred to as Spondyloarthritis (SpA).

Two main classifications of disease such as Traditional ApA Classification System and the Newer SpA Classification System.

Six types of diseases under Traditional SpA Classification System.

(1) Ankylosing Spondylitis (AS) is a type of arthritis:

  • Feeling back pain due to inflamed spine or pelvis.
  • Involve in the activities to improve the back pain.
  • Do not sit at one place for prolong period of time.
  • Often the pain occurs in the morning stiff neck and lasts approximately 30 mins.
  • This is due to the genetic variation of the gene HLA-B27 on chromosome 6p21.3. HLA stands for Major Histocompatibility Complex, Class I, B.
  • The research also indicates that the development of this disease also depends on the function of IL-23 pathway. (Ref: Article).
  • IL-23 is essential for the differentiation of Th17 lymphocytes, a subtype of T lymphocyte implicated in chronic inflammatory/autoimmune mediated diseases. (Ref: IL-23)

(2) Enteropathic Arthritis (EnA):

  • In addition to the inflamed back or joint pain, this disease includes intestine inflammation including the bowel (IBD).
  • Symptoms could include abdominal pain, diarrhea, or blood in the stool.
  • The common disease associated with this  EnA includes Crohn’s(ileitis), ulcerative colitis (UC) (colitis ulcerosa), and undifferentiated colitis.
  • Crohn’s(ileitis) : Caused by mutation of gene NOD2 (Nucleotide Binding Oligomerization Domain Containing 2). This could affect any part of the gastrointestinal tract from the mouth to the anus, but most frequently it involves the terminal ileum and colon. While, ulcerative colitis, the inflammation is continuous and limited to rectal and colonic mucosal layers. (Ref: NOD2 GeneCard)
Chromosome 16. NOD2. Located at 16q12.1

(3) Psoriatic Arthritis:

  • Psoriatic is a skin inflammatory disease that causes regular rashes on elbows, knees, and scalp.
  • Due to multiple gene dysfunctions such as HLA-C on chromosome 6p21 and sequence variant of TNFA (Tumor Necrosis Factor Alpha) and LTA (Lymphotoxin Alpha)  genes.
  • The disease associated with LTA(Lymphotoxin Alpha) gene are Psoriatic Arthritis and Leprosy 4.
  • LTA, TNFA & HLA-C genes are located in Chromosome 6, 6p21.33.
Chromosome 6. Location of LTA, TNFA & HLA-C genes. 6p21.33

(4) Reactive Arthritis:

Due to bacteria infection in the other part of the body, Reactive Arthritis arises at joints and swelling. Often at in the knees, ankles, and feet. In some cases, inflammation also occurred in the bowel or genital areas.

(5) Undifferentiated spondyloarthritis (USpA):

When clinicians were unable to find specific symptoms and signs related to a specific category of spondylitis.

(6) Juvenile Spondyloarthritis (JSpA):

  • Also called childhood rheumatic diseases and the disease developed before the age 16.
  • Affects more boys than girls.
  • Exacts genes causes of this disease is unknown. Could be related to both environmental and genetic factors.
  • Could be related to the functioning factor of gene HLA-B27 or the pathway.

Newer SpA Classification System:

(1) Axial Spondyloarthritis (AxSpA):

  • Due to inflammation of spine or pelvis hence the back pain. This disease is divided into 2 categories such as nonradiographic and radiographic sacroiliitis.
  • Nonradiographic sacroiliitis impacts the quality of life and could progress to ankylosing spondylitis.
  • Radiographic sacroiliitis Spine movement is restricted and also reduces the function. (Ref: AxSpA ).

(2) Peripheral Spondyloarthritis (pSpA):

  • Inflammation may occur where the tendons and ligaments are meet with bones including toes or fingers.