Heritability Estimation of Multiple Sclerosis Related Plasma Protein Levels in Sardinian Families with Immunochip Genotyping Data

This work aimed at estimating narrow-sense heritability, defined as the proportion of the phenotypic variance explained by the sum of additive genetic effects, via Haseman-Elston regression for a subset of 56 plasma protein levels related to Multiple Sclerosis (MS). These were measured in 212 related individuals (with 69 MS cases and 143 healthy controls) obtained from 20 Sardinian families with MS history. Using pedigree information, we found seven statistically significant heritable plasma protein levels (after multiple testing correction), i.e., Gc (h(2) = 0.77; 95%CI: 0.36, 1.00), Plat (h(2) = 0.70; 95%CI: 0.27, 0.95), Anxa1 (h(2) = 0.68; 95%CI: 0.27, 1.00), Sod1 (h(2) = 0.58; 95%CI: 0.18, 0.96), Irf8 (h(2) = 0.56; 95%CI: 0.19, 0.99), Ptger4 (h(2) = 0.45; 95%CI: 0.10, 0.96), and Fadd (h(2) = 0.41; 95%CI: 0.06, 0.84). A subsequent analysis was performed on these statistically significant heritable plasma protein levels employing Immunochip genotyping data obtained in 155 healthy controls (92 related and 63 unrelated); we found a meaningful proportion of heritable plasma protein levels' variability explained by a small set of SNPs. Overall, the results obtained, for these seven MS-related proteins, emphasized a high additive genetic variance component explaining plasma levels' variability.