## Problem 024 — rank:121

**Title:** Rare-versus-common variant architecture

**Added binding assumptions (LaTeX):**

```latex
The within-bin variance is well-defined, but bin variances need not sum to total genetic variance under linkage disequilibrium. Include $2\sum_{k<k'}\operatorname{Cov}(A_k,A_{k'})$, where $A_k$ denotes a bin's genetic value, and similarly for overlapping functional classes. Fix frequency estimates and their sampling law; distinguish conditional fixed-effects variance from a random-effects variance component.
```

**Direct edits:** 0. **Fresh external checks:** SC07