Multivariate sex-limitation script in OpenMx, correlated factors solution

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trinewa's picture
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Joined: 11/30/2009

For anyone interested in running multivariate genetic models with sex as a moderating variable, here is a script
based on the correlated factors approach to ensure that the order of the variables does not affect the ability of the model to account for the DZOS data.
(Ref: Neale et al., Multivariate genetic analysis of sex-lim and G x E interaction, Twin Research & Human Genetics, 2006 ).

The author is dr.Frühling Rijsdijk, who has approved of the sharing of the script.

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MVcor3var_ IP_CP_OpenMx.R55.19 KB
Tom Kubarych's picture
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Joined: 10/13/2009
script MVcor3var_IP_CP_OpenMx.R

I am going to try to use this script for 4 ordinal variables . I have a question about the variables. The first 4 are:

T1SEX T2SEX T1AGE T2AGE

which I assume means "twin 1 sex" "twin 2 sex" "twin 1 age" "twin 2 age".

-Correct?

Then we have:

T1M T2M T1F T2F

-Is this "trait 1 males, trait 2 males, trait 1 females, trait 2 females" ?

Then we have:

T1T T2T ZYG ZYGSEX

- what are T1T, T2T and ZYGSEX? It was originally a 3-variable script, so I was expecting to see "T3M" and "T3F". Is ZYGSEX just zyg multiplied by sex?

Thanks,

Tom

Julia's picture
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Joined: 03/29/2012
two double-headed arrows?

Thank you for the script! It is indeed very useful.
I know it's been quite a while since it was posted, but I'd like to ask you a detailed question. The within-trait cross-twin covariance (for DZOS pairs) is here defined as: am %*%(CorMFa%*%Raf)%*% t(af) . As far as I understand, here Raf is a genetic correlation between traits in female pairs and CorMFa is a genetic correlation within a trait, but across DZOS pairs. In this case we get two double-headed arrows in the path, and this is not allowed as far as I remember. Am I misunderstanding something?
Thank you.
Julia