INTRODUCTION

1. INTRODUCTION What is your name? Where are you from? What was your motivation to attend JPEMS? Do you know already what medical profession you choose? What are your first impressions on Medical (Clinical) Genetics? Medical (Clinical) Genetics as your future profession?

2. Genetics of multifactorial diseases MártaSzéll September 16, 2014. (late morning lecture) JPEMS Lecture, Nantes

3. Cystic fibrosis Xeroderma pigmentosum Monogenic diseses • rare diseases • Mendelian traits • rare genetic variations (mutations) in the background

4. Multifactorial diseases

5. Gene-environment interactions Gene-gene interactions Gene-gene interactions Multifactorial diseases • much more frequent (common) diseases • show familial aggregation BUT are not Mendelian traits • frequent genetic variations (polymorphisms) are in the background • BOTH genetic and environmental factors contribute to the pathogenesis Symptomes of common diseases

6. Classical example = diabetes of Pima indians Same genetic backround, different life style

7. Polygenic inheritance Phenotypes determined by several genes at different loci show a CONTINOUS DISTRIBUTION in a given population (height, intelligence etc.) Distribution of phenotypic values for a trait influenced by four genes

8. accumulation of disease causing gene variants Liability The liability/treashold model of multifactorial inheritence: a good model for the explanation why ceratin common diseses are more frequent in ceratain families

9. Frequency and heritability of multifactorial diseases in a population Frequency: 0.1 – 4% (congenital dislocation of the hip - asthma) Heritability: 35 – 85 % (congenital heart disease – schizopheria)

10. Multifactorial human diseases Multifactorial ethology: • Environmental factors • Genetic background Genetic heterogeneity: different genes and gene groups cause similar symptoms symptoms

11. Aggravating circumstances of genetic examination • Symptoms often change, different appearance forms may occur in time • Multifactorial diseases often occur together, establishment of homogeneous patients’ groups is very complicated

12. Examinations of the inheritance of multifactorial disorders Segregation analysis: Whether a phenotype (observable characteristic of a disease) does descendstogether with genetic markers in families Twin studies: concordance of diseases (collective occurrence in monozygotic twins) depends on environmental conditions example: allergic asthma 75% - under highly predisposing conditions 26% - under less predisposing conditions Examination of„founder” populations inspection of isolated homogenous populations due to geographical (islands) or society (religious groups) barriers. Genetic imprinting example: atopic dermatitis is inherited mainly from the mother (intrauterine influences, brest feeding?) Answer: epigenetics

13. Genetic examinations • Hypothesis-drivenexaminations (case-controlstudies): • Basedonresults of pathophysiology, molecularmedicine/biologyresearchweknowif a certain protein playsroleinthepathogenesis a givendisorder • Wecomparethefrequency of thegeneticalterations (SNP, VNTR, CNV) of thegivengeneencodingforthe protein bothinhealthy and affectedpopulations • Example: promoterpolymorphisms (SNPs) of the TNFA geneinvariousinframmatorydiseases • Investigationswithoutpreconceptions: - genome-wide association studies (GWAS): comparation of 100 thousand - 1 milliongeneticvariationsbothinhealthy and affectedpopulations - partialgenomeassociationstudies: examinations of restrictedchromosomalregionsbasedon GWAS results

14. Susceptibility genetic factors of Type II diabetes in the Chinese population 6952 T2D patients 11 865 healthy controls 1 934 619 SNP (single nucleotide polymorphism) Manhattan plot Functional and clinical relevance of the identified genes and polymorphisms

15. Genetics of Diabetes

16. Genetics of Diabetes Type 1 Diabetes (IDDM) 15-fold increased risk for 1st degree relatives Strong HLA associations: DRB1-DQB1 haplotypes determine the risk of IDDM. High risk haplotypes: • DQA1*0501-DQB1*0201 • DQA1*0301-DQB1*0302 Other associated HLA regions: HLA B8, B15, DR3, DR4 Caused by the destruction of pancreatic beta cells. (www.hindawi.com)

17. Genetics of Diabetes Genome Screens for IDDM

18. Genetics of Diabetes IDDM2 IDDM12 • Cytotoxic T Lymphocyte Associated-4 (CTLA-4)gene • Chr2q33, OMIM: 123890 • Encodes a T cell receptor that plays role in T cell apoptosis • c.A49G, p.Thr17AlaSNP • Relative increase in risk ~ 1.2 • Dysfunction of CTLA-4plays a pivotalroleinthe development of IDDM. • Insulin (INS) gene • Chr 11p15, OMIM: 176730 • 5’ UTR of the INS gene contains VNTR: • Class I: 26-63 repeats • Class II: ~80 repeats • Class III: 141-209 repeats • Relative increase in risk is ~2-fold with class I alleles

19. Genetics of Diabetes Elucidating the genetic background of NIDDM: Type 2 Diabetes (NIDDM) Individuals with a positive family history are about 2-6 times more likely to develop NIDDM than those with a negative family history. • Selected candidategenesinvolved in • Pancreatic beta cell function • Insulin action / glucose metabolism • Energy intake / expenditure • Lipid metabolism • Genome wide association studies • Current approach based on thousands of cases and controls

20. Genetics of Diabetes Type 2 Diabetes (NIDDM) (Herder et al., 2011)

21. (Herder et al., 2011)

22. Genetics of Diabetes PPARγ TCF7L2 • Transcription factor 7-like 2 (TCF7L2) gene • Chr 10q25, OMIM 602228 • Related to impaired insulin release, reduced β-cell mass or β-cell dysfunction • Genetic variant: rs7901695 • Estimated relative risk ~ 1.4 Peroxisome proliferator-activated receptor-γ (PPARγ) gene Chr 3p25, OMIM: 601487 Transcription factor in adipocyte differentiation Associated with decreased insulin sensitivity Genetic variant: p.Pro12Ala, Pro is risk allele Estimated relative risk = 1 – 3 May be responsible for ~25% of NIDDM cases

23. Genetics of Diabetes Monogenic forms of diabetes Maturity-onset diabetes of theyoung (MODY) Main features: • Prevalence: <0.01% • Age of onset: adolescence • Autosomal dominant inheritance • Absence of obesity, no ketosis,noautoimmunity • Pathophysiology: β-cell dysfunction (Barry et al., 2008)

24. Genetics of Diabetes Monogenic forms of diabetes Neonatal diabetes Main features: • Prevalence: <0.001% • Age of onset: before 6 months • Autosomaldominantorautosomalrecessive • Transientorpermanent • Pathophysiology: β-cell dysfunction (Pearson et al., 2006)

25. Pathomechanism of psoriasis genetic factors environmental conditions ? keratinocyte hyperproliferation and inflammation

26. Psoriasis is an inherited disease Monozygotic twins Dizygotic twins 60-70% (concordance) 10-15% when both have or both lack a given trait (in this case psoriasis)

27. Psoriasis is an inherited disease PARENTS P+ P- P+ P+ CHILDREN 51% 83% Swanbeck at al., 1997

28. Classical linkage group examinations = Analysis of predisposing chromosomal regions

29. Classical linkage group examinations = Analysis of predisposing chromosomal regions

30. PSORS1 locus

31. genes pseudogenes distance Narrowing the PSORS1 locus and identifying the predisposing genes

32. Genes with variations of the narrowed PSORS1 locus NOB4, NOB5, HCGII-2 – pseudogenes, out of interest HLA-C gén – antigene presentation OTF3 – octamer binding factor TCF19 – potential trans-activating factor that could play an important role in cell cycle progression HCR – α-helix coiled coil rod homolog transcription factor CDSN - corneodesmosin, required for desquamation SPR1, SEEK1 és STG1 – genes with yet unknown function

33. Some psoriasis susceptibility-related genetic factors affect the immune regulation, others influence keratinocytefunctions corneodesmosin HLA-C ZNF750 INV, SPRR3, PRR9 IRF-2 cystatin A MUC16 IL-23R MMP-2? IL-15? IL-12B

34. Some psoriasis susceptibility-related genetic factors affect the immune regulation, others influence keratinocytefunctions corneodesmosin HLA-C ZNF750 IRF-2 INV, SPRR3, PRR9 cystatin A MUC16 IL-23R MMP-2? IL-15? IL-12B

35. Some psoriasis susceptibility-related genetic factors affect the immune regulation, others influence keratinocytefunctions corneodesmosin HLA-C ZNF750 INV, SPRR3, PRR9 IRF-2 cystatin A MUC16 IL-23R MMP-2? IL-15? IL-12B

36. Results of genome wide association studies (GWAS) in psoriasis

37. Gene-environment interactions in multifactorial diseases

38. Synthesis of cis-urocanic acid and its role in skin immune suppression Histidine ammonia-lyase (histidase, HAL) trans-urocanic acid (trans-UCA) cis-urocanic acid (cis-UCA) L-histidine Pleiotrop effects on skin immune functions: • alteration of tumor antigen presentation by Langerhans cells • release of histamine and cytokines etc.

39. HAL specific staining isotype control staining Barresi, 2010 1317 ATT Isoleucine (I) 439 Valin (V) 1317 GTT Expression of HAL protein in human skin HAL protein is encoded by the HAL gene localized on human chromosome 12q22 it has only one non-synonimous coding polymorphism

40. The effect of HAL I439V polymorphism on susceptibility to non-melanoma skin cancer (NMSC) 914 BCC patients 702 SCC patients 848 healthy controls all New Hampshire Caucasians detailed questionnaries – sunbathing habits, medications etc. Examination of genotype frequencies (AA vs. AG vs. GG) in the study population Welsh, 2008

41. Results • the HAL I439V polymorphism ITSELF does not have an effect on non-melanoma skin cancer (NMSC) susceptibility BUT • when controls, BCC patients and SCC patients were stratified according to their SUNBURN history, a significant sunburn-genotype interaction was apparent for SCC p=0.040 for BCC p=0.018 • HAL genotype – SCC association was observed primarily among women OR = 1.5 (CI 1.1-2.2) Welsh, 2008

42. estrogen, glukocorticoids Histidine ammonia-lyase (histidase, HAL) trans-urocanic acid (trans-UCA) cis-urocanic acid (cis-UCA) L-histidine Pleiotrop effects on skin immune functions: • alteration of tumor antigen presentation by Langerhans cells • release of histamine and cytokines etc. Regulation of HAL gene expression

43. Results interaction between AG/GG HAL genotypes AND oral contraceptive use increased risk to SCC OR 3.7 (CI 1.9-7.5) interaction between AG/GG HAL genotypes AND oral glucocorticoid use increased risk to BCC OR 2.3 (CI 0.9-5.6) increased risk to SCC OR 6.6 (CI 2.8-15.8) Welsh, 2008

44. HAL I439V polymorphism SUMMARY Welsh, 2008 BCC SCC

45. The multifactorial nature of common dental diseases

46. Susceptibility genes investigated in periodontal disease – hypothesis driven approach

47. Treashold theory for periodontal diseases

48. Genome wide association study ( GWAS) – investigation without preconception Control population N= 1909 Severe chronic periodontitis N= 958 Moderate chronic periodontitis N= 2293 Number of examined SNPs: 906 600

49. Genome wide association study ( GWAS) – investigation without preconception The identified genes: Severe CP: WNT5A: wingless-type MMTV integration site family, member 5A: Secreted signalling protein playing a role in cell fate regulation, embryogenesis and oncogenesis NPY: neuropeptide Y: influences many physiological processes, including cortical excitability, stress response, food intake, circadian rhythms and cardiovascular function NIN: ninein: this protein is important for positioning and anchoring the microtubules minus-ends in epithelial cells

50. Genome wide association study ( GWAS) – investigation without preconception The identified genes: Moderate CP: NCR2: natural cytotoxicity triggering receptor 2 CELF2: Elav-like family member 2: an RNA binding protein playing role in various RNA-related cellular functions EMR1: egf-like module containing, mucin-like, hormone receptor-like 1