1. Genetics: A piece of the puzzle Michael J. Ombrello, M.D. Senior Clinical Fellow, Inflammatory Disease Section National Human Genome Research Institute National Institutes of Health Michael.Ombrello@nih.gov

2. Genetics: A piece of the puzzle Michael J. Ombrello, M.D. Senior Clinical Fellow, Inflammatory Disease Section National Human Genome Research Institute National Institutes of Health Michael.Ombrello@nih.gov

3. Himmelfarb J. et al. Kidney International (2002) 62: 1524–1538.

4. What is Juvenile Idiopathic Arthritis? Juvenile arthritis Juvenile rheumatoid arthritis Juvenile chronic arthritis Juvenile idiopathic arthritis: Onset of symptoms prior to 16th birthday Arthritis present > 6 weeks without other cause { Juvenile Idiopathic Arthritis Petty R.E. et al. J Rheumatology (2004) 31:390-392.

5. Classification Criteria of JIA International League of Associations for Rheumatology (ILAR) Classification Criteria: Systemic arthritis Oligoarthritis Rheumatoid factor positive polyarthritis Rheumatoid factor negative polyarthritis Psoriatic arthritis Enthesitis related arthritis Undifferentiated arthritis Petty R.E. et al. J Rheumatology (2004) 31:390-392.

6. Review of genetics principles What is DNA? What is a chromosome? What is a gene? What is a protein? Why perform genetic research? What is a simple genetic trait? What is a complex genetic trait?

7. What is DNA? Deoxyribonucleic Acid

8. What is a chromosome? Largest organizational unit of genetic material One cell has 6 feet of DNA Linear DNA folds into chromosomes Normal Human Female Image courtesy of U.S. National Library of Medicine

9. What is a gene? The organizational unit of DNA that produces one specific protein Range of 300 to 4300 genes per human chromosome Humans have 20,000 – 25,000 genes

10. DNA is the template for making proteins Proteins are the things within cells that “do” things Changes in DNA code may change the structure and function of the protein it encodes

11. What can genetics research teach us? We hope to identify: Genetic variants that affect risk Cellular pathways Identification of these things may: Reveal a novel or unrecognized therapeutic target Allow prediction of therapeutic response Uncover a novel biomarker Advance our understanding of disease process

12. Mendelian (Simple) Genetics Simple Genetic Trait GregorMendel first described in garden peas A trait (phenotype) caused by variation in a single gene Dominant trait caused by 1 copy of genetic variant Recessive trait caused by 2 copies of genetic variant

14. Hemophilia

15. Duchenne Muscular Dystrophy

17. Complex Genetics Complex genetic traits in humans Eye color Hair color Blood type (ABO) Tongue rolling Complex genetic diseases in humans Cancer Lung cancer Autoimmune Diseases Rheumatoid arthritis Inflammatory bowel disease Type 1 diabetes mellitus Atherosclerosis Parkinson’s disease Autism Juvenile Idiopathic Arthritis

18. Types of Genetic Studies Candidate gene studies Investigator chooses gene Variants/markers in the region are typed Compare frequency of markers Advantages of candidate gene studies Low cost study design Relatively easy to perform Limitations of candidate gene studies Selection bias for genes studied Differences in ethnic composition of cases and control groups Sampling bias unless many individuals studied Results are inconsistently replicated

19. Types of Genetic Studies Genome-wide association studies Performed using commercial arrays that type variants/markers across the entire genome (usually over 1 million markers) Compare frequency of many more markers Advantages of genome wide association studies Genome wide data allows exclusion of ethnically dissimilar subjects Unlimited ability to detect Limitations of genome wide association studies Require very large numbers of cases and controls Relatively expensive to perform Arrays only examine common variants

20. Manolio T. N Engl J Med 2010; 363:166-176.

21. Genetics of juvenile arthritis

22. “Lumping” studies of Juvenile Arthritis ARGUMENT AGAINST “LUMPING” STUDIES The seven JIA subtypes are different diseases We should not expect the same genetic causes ARGUMENT FOR “LUMPING” STUDIES JIA is rare, and lumping increases statistical power Though different, all subtypes involve arthritis developing at a young age All JIA subtypes appear to be complex diseases Some genes are bound to overlap among types

23. “Juvenile Idiopathic Arthritis” Autoimmunity susceptibility genes TNF-a: Inflammatory cytokine with broad effects Numerous therapeutics are widely used in JIA CTLA-4: Signaling molecule that protects “self” from T cells Therapeutic in use as second line agent in JIA PTPN22: Signaling molecule that affects adaptive immune system Variants can influence autoimmunity STAT4: Transcription factor for inflammatory genes

25. Arthritis

26. Fever

27. One or more of the following:

28. Rash

29. Generalized lymphadenopathy

30. Organomegaly

31. Serositis

32. Causes are poorly understood

33. Innate immune involvement

34. Unclear role of adaptive immunity

35. Autoimmune vs. autoinflammatorySir George Frederick Still

36. Adaptive vs. Innate Immune Systems Innate Immunity Innate immune cells Macrophage/monocyte Neutrophil Mast cell Receptors (sensors) Detect products of pathogens Detect host danger signals NOT variable Inflammatory cytokines Adaptive Immunity Adaptive immune cells B lymphocyte (antibodies) T lymphocyte Receptors (sensors) Detect pieces of protein VARIABLE (via recombination) Inflammatory cytokines

37. Genetic Studies of Systemic Arthritis Receptor for inflammatory cytokines Inflammatory cytokines Receptors for inflammatory cytokines Inflammatory cytokine Anti-inflammatory cytokine Inflammatory cytokine Ion channel Antigen recognition

39. Small, specific “binding cleft”

41. Genome Wide Association Study of Systemic Arthritis

42. Oligoarthritis Oligoarticular JIA is characterized by: Arthritis present in 4 or less joints at presentation Persistent oligoarthritis: Arthritis “persists” in 4 or less joints Extended oligoarthritis: Arthritis “extends” to involve >4 joints High rate of inflammatory eye disease (uveitis) Very strong association with specific MHC types Functional importance is not clear

43. Polyarthritis (RF negative) RF negative polyarticular JIA is characterized by: Arthritis present in 5 or more joints at presentation Typically more large joint involvement Often asymmetrical involvement Absent rheumatoid factor Rate of eye disease comparable to oligoarthritis

44. Polyarthritis (RF positive) RF positive polyarticularJIA is characterized by: Arthritis present in 5 or more joints at presentation Typically involves large and small joints Clinical course is comparable to rheumatoid arthritis

45. Psoriatic Arthritis Psoriatic JIA is characterized by: Arthritis and psoriasis Arthritis PLUS 2 of the following: Dactylitis (sausage-like swelling of a digit) Characteristic fingernail changes Psoriasis in a first degree relative Much genetic work in adult form of the disease Interleukin 23 receptor plays a central role Therapeutic against this already FDA approved for psoriasis Still under consideration for psoriatic arthritis

46. Enthesitis Related Arthritis Enthesitis-related JIA (ERA) is characterized by: Arthritis and enthesitis, OR Arthritis OR enthesitis, AND 2 or more of the following Sacro-iliac joint tenderness or inflammatory back pain HLA-B*27 antigen positive Arthritis in male over 6 years of age Acute anterior uveitis History of similar disease in first degree relative HLA-B*27 is strongest association (MHC gene) Other genes have been identified in adult form of disease

47. Summary State of the art genetic studies are coming to JIA In the past  candidate gene studies Today  genome wide association studies Tomorrow  whole genome sequencing studies The scale and scope of the studies are expanding Larger numbers of patients being enrolled (collaboration) Larger numbers of markers being checked (technology) Separate investigations of different JIA subtypes

48. Questions or Comments? If you are interested in more information about our ongoing genome wide association study of systemic juvenile idiopathic arthritis, please ask me or send an email to: Michael.Ombrello@mail.nih.gov