Fig. 1: Frequency of IgG1 allotypes in Iceland and Sweden and association with IgG1 levels.

IgG1 allotypes are defined by one or more missense variants. For each allotype, we include the conventional allotype name, the IMGT numbering, and allotype defining amino acids (AA) at given positions within the IgG1 protein (Eu numbering). Below the respective rsID for the single-nucleotide polymorphism is indicated. Underlined AAs indicate changes from the top allotype, G1m(za). We used phased haplotype data to define the IgG1 allotypes based on the unique presence/absence combination of the missense variants detected in IGHG1 in both Icelanders and Swedes. Single nucleotide polymorphisms (SNPs) corresponding to the underlined AA changes are shown in red. Positions of the missense variants are given in the human reference genome build Hg38 (a). Frequency (%) of the different allotypes found in Icelanders and Swedes (b). Schematic representation of antibody molecules showing the approximate location of the allotype defining AAs. Box plots showing absolute IgG1 serum levels, stratified on allotypes. IgG1 serum levels are plotted for the three most frequent allotypes in Iceland and Sweden (c). Throughout the figure we keep the same color code for the different allotypes, yellow=G1m(za), pink=G1m(f), green=G1m(zax), grey=G1m(zav) and blue=G1m(fa). Single letter codes are used for the AAs, Lysine (K), Aspartic Acid (D), Leucine (L), Valine (V), Alanine (A), Arginine (R), Glutamic Acid (E), Methionine (M), Glycine (G) and Isoleucine (I). In the box plots, the bottom and top of the boxes correspond to the 25th (Q1) and 75th (Q3) percentiles, the line inside the box is the median, and the whiskers are located at Q1 – 1.5 IQR and Q3 + 1.5 IQR (where IQR is the interquartile range, Q1–Q3). c n represents number of carriers where a given IgG1 allotype 0 = non-carrier, 1 = heterozygous carriers and 2 = homozygous carriers.