title: Heritability and GWAS Studies for Monocyte-Lymphocyte Ratio.
abstract: The monocyte-lymphocyte ratio (MLR) is a useful biomarker for disease development, but little is known about the extent to which genetic and environmental factors influence MLR variation. Here, we study the genetic architecture of MLR and determine the influence of demographic and lifestyle factors on MLR in data from a Dutch non-patient twin-family population. Data were obtained in 9,501 individuals from the Netherlands Twin Register. We used regression analyses to determine the effects of age, sex, smoking, and body mass index (BMI) on MLR and its subcomponents. Data on twins, siblings and parents (N = 7,513) were analyzed by genetic structural equation modeling to establish heritability and genome wide single nucleotide polymorphism (SNP) data from a genotyped subsample (N = 5,892) and used to estimate heritability explained by SNPs. SNP and phenotype data were also analyzed in a genome-wide association study to identify the genes involved in MLR. Linkage disequilibrium (LD) score regression and expression quantitative trait loci (eQTL) analyses were performed to further explore the genetic findings. Results showed that age, sex, and age × sex interaction effects were present for MLR and its subcomponents. Variation in MLR was not related to BMI, but smoking was positively associated with MLR. Heritability was estimated at 40% for MLR, 58% for monocyte, and 58% for lymphocyte count. The Genome-wide association study (GWAS) identified a locus on ITGA4 that was associated with MLR and only marginally significantly associated with monocyte count. For monocyte count, additional genetic variants were identified on ITPR3, LPAP1, and IRF8. For lymphocyte count, GWAS provided no significant findings. Taking all measured SNPs together, their effects accounted for 13% of the heritability of MLR, while all known and identified genetic loci explained 1.3% of variation in MLR. eQTL analyses showed that these genetic variants were unlikely to be eQTLs. In conclusion, variation in MLR level in the general population is heritable and influenced by age, sex, and smoking. We identified gene variants in the ITGA4 gene associated with variation in MLR. The significant SNP-heritability indicates that more genetic variants are likely to be involved.
authors.affiliation: Netherlands Twin Register,Department of Biological Psychology,Vrije Universiteit,Amsterdam,the Netherlands.
authors.forename: Bochao D
authors.initials: BD
authors.lastname: Lin
authors.affiliation: Netherlands Twin Register,Department of Biological Psychology,Vrije Universiteit,Amsterdam,the Netherlands.
authors.forename: Gonneke
authors.initials: G
authors.lastname: Willemsen
authors.affiliation: Netherlands Twin Register,Department of Biological Psychology,Vrije Universiteit,Amsterdam,the Netherlands.
authors.forename: Iryna O
authors.initials: IO
authors.lastname: Fedko
authors.affiliation: Department of Psychiatry,VU Medical Center,Amsterdam,the Netherlands.
authors.forename: Rick
authors.initials: R
authors.lastname: Jansen
authors.affiliation: Department of Psychiatry,VU Medical Center,Amsterdam,the Netherlands.
authors.forename: Brenda
authors.initials: B
authors.lastname: Penninx
authors.affiliation: Netherlands Twin Register,Department of Biological Psychology,Vrije Universiteit,Amsterdam,the Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: de Geus
authors.affiliation: Good Biomarker Sciences,Leiden,the Netherlands.
authors.forename: C
authors.initials: C
authors.lastname: Kluft
authors.affiliation: Netherlands Twin Register,Department of Biological Psychology,Vrije Universiteit,Amsterdam,the Netherlands.
authors.forename: JoukeJan
authors.initials: J
authors.lastname: Hottenga
authors.affiliation: Netherlands Twin Register,Department of Biological Psychology,Vrije Universiteit,Amsterdam,the Netherlands.
authors.forename: Dorret I
authors.initials: DI
authors.lastname: Boomsma
mesh_terms: D000328:Adult; D015992:Body Mass Index; D005260:Female; D005819:Genetic Markers; D020022:Genetic Predisposition to Disease; D055106:Genome-Wide Association Study; D006801:Humans; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000235:genetics; D039001:Integrin alpha Chains / Q000235:genetics; D050835:Interferon Regulatory Factors / Q000235:genetics; D015810:Linkage Disequilibrium; D008214:Lymphocytes / Q000166:cytology*; D008297:Male; D008875:Middle Aged; D009000:Monocytes / Q000166:cytology*; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D019655:Quantitative Trait, Heritable; D049368:Receptors, Lysophosphatidic Acid / Q000235:genetics; D012907:Smoking / Q000009:adverse effects; D000099185:Interferon Regulatory Factor-8
chemical_list: D005819:Genetic Markers; D053496:Inositol 1,4,5-Trisphosphate Receptors; D039001:Integrin alpha Chains; D050835:Interferon Regulatory Factors; D049368:Receptors, Lysophosphatidic Acid; D000099185:Interferon Regulatory Factor-8; C506929:ITPR3 protein, human; C000609549:LPAR1 protein, human
keywords: GWAS; MLR; age and sex differences; heritability; lifestyle