question regarding the blue line on pedigree

[wgc517]

I know that the blue line represent the x factor but how is it determined to be given to a horse. Are they still being updated oon the site or not? Any information or insight would be appreciated.

[Pan Zareta]

The blue line appears under 'double copy' mares. Otherwise the X-factor line is red. Updates are possible, but are done by the research team. Please post any horses you believe should be designated as carriers.

[wgc517]

Thanks for the reply. I do understand that the blue line represents the double x but how do you know that a horse carries the double x. Is there a test? Do you measure the heart. Who makes the decision and how do they come to it.

[Pan Zareta]

Heart size is objectively determined (scored) via ecg & u/s, and/or direct examination (usually post-mortem). The vast majority of individuals in the pq db that are designated X-factor carriers were identified based upon circumstantial evidence derived from pedigrees, performance, and the hypothetical sex-linked transmission of the trait as set forth in Marianna Haun's publications.