Portrait of Austrian writer Karl Kraus reading and holding a cigar; Berlin Portraits Men

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Portrait of Paul Kraft; Stockholm Portraits Men

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Fini Loewenthal with Justin Loewenthal in uniform; Regensburg Portraits Men

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Henry Rosenbaum seated at a desk smoking a cigar and sketching; New York Portraits Men

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Portrait of Justin Loewenthal; Regensburg Portraits Men

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Portrait of Erna Loewi Portraits Men

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Herman Sommerfeld (center) with other reserve soldiers in military uniform Portraits Men

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Herman Sommerfeld (center) with other soldiers in military uniform Portraits Men

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Herman Sommerfeld, German Jewish World War I pilot, seated in an airplane Portraits Men

Signed by photographer bottom left

Herman Sommerfeld (right) in military uniform with an unidentified soldier Portraits Men

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Herman Sommerfeld with unidentifed men and women on board a ship from Tallin to Helsinki (and on to the United States) Portraits Groups

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Studio portrait of Herman Sommerfeld in military uniform Portraits Men

Handwritten on verso: Zur Erinnerung an meiner ? Zeit, Dein Hermann, Flughafen-Doberitz, Zum austuecken bereit

Herman Sommerfeld (fifth from right) with other soldier recruits; Döberitz, Germany Portraits Men

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Portrait of Herman Sommerfeld (right) with two unidentified pilots of the naval air force; Adlershof bei Berlin Portraits Men

Caption reads: Werftbild Abtl Flugzeugmeisterei Adlershof bei Berlin 1917

Genome-wide meta-analysis of common variant differences between men and women

The male-to-female sex ratio at birth is constant across world populations with an average of 1.06 (106 male to 100 female live births) for populations of European descent. The sex ratio is considered to be affected by numerous biological and environmental factors and to have a heritable component. The aim of this study was to investigate the presence of common allele modest effects at autosomal and chromosome X variants that could explain the observed sex ratio at birth. We conducted a large-scale genome-wide association scan (GWAS) meta-analysis across 51 studies, comprising overall 114 863 individuals (61 094 women and 53 769 men) of European ancestry and 2 623 828 common (minor allele frequency >0.05) single-nucleotide polymorphisms (SNPs). Allele frequencies were compared between men and women for directly-typed and imputed variants within each study. Forward-time simulations for unlinked, neutral, autosomal, common loci were performed under the demographic model for European populations with a fixed sex ratio and a random mating scheme to assess the probability of detecting significant allele frequency differences. We do not detect any genome-wide significant (P < 5 x 10(-8)) common SNP differences between men and women in this well-powered meta-analysis. The simulated data provided results entirely consistent with these findings. This large-scale investigation across ~115 000 individuals shows no detectable contribution from common genetic variants to the observed skew in the sex ratio. The absence of sex-specific differences is useful in guiding genetic association study design, for example when using mixed controls for sex-biased traits.