I am aiming at evaluating the genetic correlation among ~150 continuous traits measured in ~1100 twin pairs (~2200 individuals). I have already run GWASs for each trait (using an LMM as implemented in GEMMA), therefore, I have both the genetic data and the GWAS summary statistics.
I had a look at the literature, and LDSC seems a pretty popular approach. However, due to our small-ish sample size (N<5000) and the fact that GWASs were run using an LMM, LDSC cannot be used with our data.
Unfortunately, also approaches based on genetic data (e.g., GTCA, BOLT-REML) seem, to the best of my understanding, to be unsuitable, since they require unrelated individuals. I am aware that I could simply remove one twin from each pair, but I would avoid halving my sample size.
I am now wondering whether anyone is aware of any other approach that allows for related data, or whether anyone has any suggestion.
Many thanks in advance!