# How to interpret this statement on missing heritability

I'm currently studying a behavioral genetic course, but still, I feel that I'm lacking many basic concepts.
A particular topic I don't understand is missing heritability.
Here's an example regarding the genetics of schizophrenia, this is what is stated in my course material: "GWAS studies have identified 240 genes associated with this disorder, but these only explain less than 10% of heritability, the missing heritability for schizophrenia is around 90%".

What does it mean that 90% of heritability is missing?
I'd like to understand the math behind this concept but I don't care if this statement is actually true, I don't know where this data came from.

PS I know how heritability is generally defined in a narrow and broad sense.

• Can you please clarify what you are asking: it seems clear from what you wrote that missing = unexplained (by known genetic factors). Does that help or is there some more subtle question that I'm missing? Commented Dec 26, 2021 at 0:47
• Still unclear. Let's say you have a $h^2 = 0.5$. What exactly does it mean 90% is unexplained? How do you obtain 0.45 as a value for this missing heritability? Commented Dec 26, 2021 at 8:04
• @Mirko It means that if we knew the effects of every SNP, we could make a predictor explaining 50% of the variance. But right now, we only can explain 0.10*50% = 5% of the variance with our current predictors. Commented Feb 29 at 3:52