Top 20 HLA Associations for MRCP Part 1
- Crack Medicine
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TL;DR
List: Top 20 HLA Associations (B27, DR3, DR4) is one of the highest-yield immunology topics in MRCP Part 1, frequently tested as direct recall and clinical vignette questions. Rather than memorising isolated facts, candidates should understand the pattern linking specific HLA types with autoimmune, inflammatory and endocrine disorders. This guide summarises the most examinable associations, common traps, memory tips and a practice MCQ to strengthen exam recall.
Core sections
Understanding the HLA groups
Before memorising diseases, remember the broad classification.
Class I: HLA-A, HLA-B, HLA-C
Present antigens to CD8 T cells
Class II: HLA-DP, DQ, DR
Present antigens to CD4 T cells
For MRCP Part 1, B27, DR3, DR4, DQ2 and DQ8 are by far the most frequently tested.
The Top 20 High-Yield HLA Associations
HLA | Disease | Exam importance |
B27 | Ankylosing spondylitis | Extremely high |
B27 | Reactive arthritis | Very high |
B27 | Psoriatic arthritis (axial type) | High |
B27 | Enteropathic arthritis | High |
B27 | Acute anterior uveitis | High |
DR3 | Type 1 diabetes | Very high |
DR4 | Type 1 diabetes | Very high |
DR3 | Graves' disease | High |
DR3 | Hashimoto thyroiditis | High |
DR3 | Myasthenia gravis | High |
DR3 | Addison's disease | High |
DR3 | Coeliac disease (also DQ2) | High |
DQ2 | Coeliac disease | Very high |
DQ8 | Coeliac disease | High |
DR4 | Rheumatoid arthritis | Very high |
DR4 | Giant cell arteritis | Moderate |
DR2 | Multiple sclerosis | Moderate |
DR2 | Goodpasture syndrome | Moderate |
B8 | Myasthenia gravis | Moderate |
B51 | Behçet disease | High |
The five most tested HLA associations
1. HLA-B27
This is the single most frequently examined HLA.
Think:
Ankylosing spondylitis
Reactive arthritis
Enteropathic arthritis
Psoriatic spondyloarthritis
Acute anterior uveitis
Whenever an MRCP question mentions:
inflammatory back pain
sacroiliitis
recurrent uveitis
enthesitis
you should immediately think HLA-B27.
2. HLA-DR4
The classic association is:
Rheumatoid arthritis
It is also associated with:
Type 1 diabetes
Giant cell arteritis
Remember:
DR4 = Destructive joints
This mnemonic helps distinguish it from DR3.
3. HLA-DR3
One HLA linked with multiple autoimmune endocrine diseases.
Common associations include:
Graves' disease
Addison's disease
Type 1 diabetes
Hashimoto thyroiditis
Myasthenia gravis
Coeliac disease
Think of DR3 as the "autoimmune endocrine" HLA.
4. HLA-DQ2 and DQ8
Although technically not DR antigens, these are commonly tested.
Nearly all patients with coeliac disease possess:
DQ2
DQ8
Remember:
Presence supports diagnosis.
Absence makes coeliac disease unlikely.
Presence alone does not confirm disease.
5. HLA-B51
Behçet disease remains a favourite examination association.
Clinical clues include:
recurrent oral ulcers
genital ulcers
uveitis
pathergy
Think:
Behçet → B51
Numbered revision list: Highest-yield memory points
B27 = Ankylosing spondylitis
B27 = Reactive arthritis
B27 = Acute anterior uveitis
DR4 = Rheumatoid arthritis
DR3 = Graves' disease
DR3 = Addison's disease
DR3 + DR4 = Type 1 diabetes
DQ2 = Coeliac disease
DQ8 = Coeliac disease
B51 = Behçet disease
DR2 = Multiple sclerosis
DR2 = Goodpasture syndrome
Practical examples / mini-cases
Mini-case
A 27-year-old man presents with inflammatory back pain, morning stiffness lasting more than one hour and recurrent episodes of painful red eyes. MRI demonstrates bilateral sacroiliitis.
Which HLA type is most strongly associated with this condition?
A. HLA-B8
B. HLA-B27
C. HLA-DR2
D. HLA-DR3
E. HLA-DR4
Answer: B. HLA-B27
Explanation
The combination of inflammatory back pain, sacroiliitis and recurrent anterior uveitis strongly suggests ankylosing spondylitis. Over 85–90% of affected patients carry HLA-B27, making it one of the strongest genetic disease associations tested in MRCP Part 1.
Practise more examination-style questions in the Crack Medicine Free MRCP MCQs:https://www.crackmedicine.com/qbank
Practical study-tip checklist
✔ Learn HLA associations in disease groups rather than individually.
✔ Memorise B27 first before learning rarer associations.
✔ Pair DR3 with autoimmune endocrine disease.
✔ Pair DR4 with rheumatoid arthritis.
✔ Remember DQ2 and DQ8 for coeliac disease.
✔ Revise using flashcards every few days.
✔ Attempt timed practice questions after revision.
✔ Reinforce learning with full-length exam simulations:https://www.crackmedicine.com/mock-tests
Five common examination traps
Trap 1: Confusing DR3 and DR4 in rheumatoid arthritis. The classic answer is DR4.
Trap 2: Assuming HLA positivity is diagnostic. It only increases disease susceptibility.
Trap 3: Forgetting that Type 1 diabetes is associated with both DR3 and DR4.
Trap 4: Missing DQ2 and DQ8 when asked about coeliac disease genetics.
Trap 5: Mixing Behçet disease (B51) with HLA-B27-associated disorders.
FAQs
Which HLA association is tested most often in MRCP Part 1?
HLA-B27 is by far the most frequently examined association because of its strong relationship with ankylosing spondylitis, reactive arthritis and anterior uveitis.
Is HLA-B27 diagnostic of ankylosing spondylitis?
No. Many healthy individuals carry HLA-B27. Diagnosis depends on the clinical picture together with imaging findings rather than HLA status alone.
Which HLA is associated with rheumatoid arthritis?
The classical association is HLA-DR4. Although multiple genetic factors contribute to rheumatoid arthritis, DR4 remains the key examination answer.
Which HLA types are linked to coeliac disease?
Most patients possess HLA-DQ2, while the remainder usually carry HLA-DQ8. These markers support diagnosis but are not diagnostic on their own.
How should I memorise HLA associations for MRCP Part 1?
Group diseases into patterns instead of learning isolated facts. Focus first on B27, DR3, DR4, DQ2 and DQ8, then reinforce knowledge through repeated MCQ practice and spaced revision.
Ready to start
Strong recall of HLA associations can convert difficult immunology questions into straightforward marks. Consolidate this topic by revising the MRCP Part 1 overview, completing the Free MRCP MCQ Bank, and testing your progress with full-length mock examinations. Regular retrieval practice is far more effective than passive reading.
Sources
MRCP(UK). https://www.mrcpuk.org/
Abbas AK, Lichtman AH, Pillai S. Basic Immunology. Elsevier.
Kumar, Abbas & Aster. Robbins & Cotran Pathologic Basis of Disease. Elsevier.
Davidson's Principles and Practice of Medicine. Elsevier.
NICE Clinical Knowledge Summaries. https://cks.nice.org.uk/
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