A phenome-wide association study of 26 mendelian genes reveals phenotypic expressivity of common and rare variants within the general population.

The clinical evaluation of a genetic syndrome relies upon recognition of a characteristic pattern of signs or symptoms to guide targeted genetic testing for confirmation of the diagnosis. However, individuals displaying a single phenotype of a complex syndrome may not meet criteria for clinical diagnosis or genetic testing. Here, we present a phenome-wide association study (PheWAS) approach to systematically explore the phenotypic expressivity of common and rare alleles in genes associated with four well-described syndromic diseases (Alagille (AS), Marfan (MS), DiGeorge (DS), and Noonan (NS) syndromes) in the general population. Using human phenotype ontology (HPO) terms, we systematically mapped 60 phenotypes related to AS, MS, DS and NS in 337,198 unrelated white British from the UK Biobank (UKBB) based on their hospital admission records, self-administrated questionnaires, and physiological measurements. We performed logistic regression adjusting for age, sex, and the first 5 genetic principal components, for each phenotype and each variant in the target genes (JAG1, NOTCH2 FBN1, PTPN1 and RAS-opathy genes, and genes in the 22q11.2 locus) and performed a gene burden test. Overall, we observed multiple phenotype-genotype correlations, such as the association between variation in JAG1, FBN1, PTPN11 and SOS2 with diastolic and systolic blood pressure; and pleiotropy among multiple variants in syndromic genes. For example, rs11066309 in PTPN11 was significantly associated with a lower body mass index, an increased risk of hypothyroidism and a smaller size for gestational age, all in concordance with NS-related phenotypes. Similarly, rs589668 in FBN1 was associated with an increase in body height and blood pressure, and a reduced body fat percentage as observed in Marfan syndrome. Our findings suggest that the spectrum of associations of common and rare variants in genes involved in syndromic diseases can be extended to individual phenotypes within the general population.

Loss of function, missense, and intronic variants in NOTCH1 confer different risks for left ventricular outflow tract obstructive heart defects in two European cohorts.

Loss of function variants in NOTCH1 cause left ventricular outflow tract obstructive defects (LVOTO). However, the risk conferred by rare and noncoding variants in NOTCH1 for LVOTO remains largely uncharacterized. In a cohort of 49 families affected by hypoplastic left heart syndrome, a severe form of LVOTO, we discovered predicted loss of function NOTCH1 variants in 6% of individuals. Rare or low-frequency missense variants were found in 16% of families. To make a quantitative estimate of the genetic risk posed by variants in NOTCH1 for LVOTO, we studied associations of 400 coding and noncoding variants in NOTCH1 in 1,085 cases and 332,788 controls from the UK Biobank. Two rare intronic variants in strong linkage disequilibrium displayed significant association with risk for LVOTO amongst European-ancestry individuals. This result was replicated in an independent analysis of 210 cases and 68,762 controls of non-European and mixed ancestry. In conclusion, carrying rare predicted loss of function variants in NOTCH1 confer significant risk for LVOTO. In addition, the two intronic variants seem to be associated with an increased risk for these defects. Our approach demonstrates the utility of population-based data sets in quantifying the specific risk of individual variants for disease-related phenotypes.

Substantial Cardiovascular Morbidity in Adults With Lower-Complexity Congenital Heart Disease.

BACKGROUND: Although lower-complexity cardiac malformations constitute the majority of adult congenital heart disease (ACHD), the long-term risks of adverse cardiovascular events and relationship with conventional risk factors in this population are poorly understood. We aimed to quantify the risk of adverse cardiovascular events associated with lower-complexity ACHD that is unmeasured by conventional risk factors. METHODS: A multitiered classification algorithm was used to select individuals with lower-complexity ACHD and individuals without ACHD for comparison among >500 000 British adults in the UK Biobank. ACHD diagnoses were subclassified as isolated aortic valve and noncomplex defects. Time-to-event analyses were conducted for the primary end points of fatal or nonfatal acute coronary syndrome, ischemic stroke, heart failure, and atrial fibrillation and a secondary combined end point for major adverse cardiovascular events. Maximum follow-up time for the study period was 22 years with retrospectively and prospectively collected data from the UK Biobank. RESULTS: We identified 2006 individuals with lower-complexity ACHD and 497 983 unexposed individuals in the UK Biobank (median age at enrollment, 58 [interquartile range, 51-63] years). Of the ACHD-exposed group, 59% were male, 51% were current or former smokers, 30% were obese, and 69%, 41%, and 7% were diagnosed or treated for hypertension, hyperlipidemia, and diabetes mellitus, respectively. After adjustment for 12 measured cardiovascular risk factors, ACHD remained strongly associated with the primary end points, with hazard ratios ranging from 2.0 (95% CI, 1.5-2.8; P<0.001) for acute coronary syndrome to 13.0 (95% CI, 9.4-18.1; P<0.001) for heart failure. ACHD-exposed individuals with ≤2 cardiovascular risk factors had a 29% age-adjusted incidence rate of major adverse cardiovascular events, in contrast to 13% in individuals without ACHD with ≥5 risk factors. CONCLUSIONS: Individuals with lower-complexity ACHD had a higher burden of adverse cardiovascular events relative to the general population that was unaccounted for by conventional cardiovascular risk factors. These findings highlight the need for closer surveillance of patients with mild to moderate ACHD and further investigation into management and mechanisms of cardiovascular risk unique to this growing population of high-risk adults.