Cluster Phenotypes - Background Phenotypes such as “asthma” are difficult to define, variable over time and/or are subject to recall bias and are “syndromic”. Subtypes of asthma are known to exist - –Eosinophilic, neutrophilic, paucigranulocytic, atopic, occupational. There are intermediate phenotypes – –IgE, atopy, AHR, FEV1, eNO Phenotypes do not “capture” “asthma” Ho: Clusters will capture phenotypes that more strongly associate with genetic variation than “asthma”

Cluster Phenotypes Cluster Analysis (SAS) Busselton Health Survey All adults with: –Age, Sex, FEV1, FVC, eNO, eosinophil count, BMI, airway hyper-responsiveness (AHR), atopy (skin tests) n = 1,970 7 clusters (each with n > 100)

Cluster Phenotypes Cluster n Doctor-diagnosed Hay Fever (%) Doctor-diagnosed Asthma (%)

Cluster Phenotypes Cluster n Cluster Variables Outcome Variables “Descriptors” High eNO, high eosinophils, low BHR, high atopy Smoke low, HF high, asthma Allergic sneezing, wheezing twitchers Females, obese, no AHR, low atopyFat Freewheelers Reduced lung function, all AHR, moderate atopy High asthmaChronic wheezers Males, no AHR, very atopicHFBlotchy blokes Males, poor lung function, no AHRSmoke highPuffing Old Blokes Younger females, no AHR, low eNO, low eosinophils, low atopy Smoke low, asthma low Sanctimonious shielas Older, good lung function, no AHR, low atopy Smoke low, HF low, asthma very low Survivors

Cluster Phenotypes - Questions How many clusters? –? Sub-clusters What other variables to collect? Include exposure? Include questionnaire data? Include treatment? Do clusters suggest pathways? Best gene association strategy –GWAS, candidate (from lit. or pathways)?

Cluster Phenotypes ClusternAge Sex (%F) FEVPPRFEVFVCeNOEOSINBMIAHRATOPY

Excessive Airway Narrowing in a General Population n = 201 James et al. ARRD 1992;146:895-9

Airway Compartments Lumen area Smooth muscle Inner wall area Outer wall area Basement membrane perimeter

Excessive Airway Narrowing

Airway smooth muscle in asthma: collaborative study James et al AJRCCM (rejected), Thorax (rejected), ERJ (submitted)

Decline in lung function - the Busselton Health Study Females James et al AJRCCM 2005;171:109

Sears M et al. N Engl J Med 2003;349: FEV1/FVC Mean (SE) from 9-26 Yrs in Males and Females, by Pattern of Wheezing A Longitudinal Study of Childhood Asthma Followed to Adulthood

Asthma (ever) (p <0.001)* *1981 vs 2005/07 Q. “Have you ever had asthma?” Q. “Has a doctor ever told you that you had asthma?”

Current Asthma (AHR + recent wheeze)

Wheeze (ever) (p <0.001)* (p <0.029)* (p <0.001)* Q. “Has your chest sounded wheezy on most days or nights?” Q. “Has your chest ever made a wheezing or whistling sound ?” *1981 vs 2005/07

Recent Wheeze Wheeze <12 months

Shortness of Breath

Cough/Phlegm (p <0.02)* *1981 vs 2005

Smoking

Bronchitis Q. “Have you ever had bronchitis? Q. “Has your doctor ever told that you had bronchitis?”