|Summary||Data Quality Warning|
Some of your data claims that you have 2 Y chromosomes. In particular it is claiming heterozygosity for a Y chromosomal SNP.
While it is true that https://en.wikipedia.org/wiki/XYY_syndrome exists, the microarrays used by 23andMe, Ancestry.com and their analysis methods and others are prone to misinterpreting the sex chromosomes. As a result Promethease sometimes sees this in their raw data.
At various times, Ancestry.com has previously addressed this at
- http://ancestryforums.custhelp.com/posts/b7de792b84?commentId=30021 (dead link)
With a similar answer from 23andMe at https://www.23andme.com/you/community/thread/40845/
Even in those rare cases where you actually are XYY, it's likely that microarray testing would fail to detect it. This is because our understanding is that the two Y chromosomes in an XYY individual should be duplicates of each other, since they come about from a nondisjunction event in meiosis (II). As duplicates, they shouldn't show heterozygosity. In other words, even in an XYY individual, the Y chromosome SNPs should not show heterozygosity, which is why this genoset is a warning for poor data quality.