Brief overview of the paper and its main findings

The authors studied a large cohort of individuals with XYY karyotype using exome sequencing, karyotyping and FISH. They have also investigated different tissues for mosaicism. The researchers investigated if XYY patients have mutations in 50 known DSD genes and try to establish a better understanding of phenotypic differences between XYY patients. The main findings of the study can be listed as below: - The XYY karyotype is more frequent in patients with DSD. - No mutation was found in known DSD genes among XYY cases. - The gonad tissues of these patients are in fact mosaic for X/XY and XYY.

Major and minor points The authors used different molecular methods to identify the XYY karyotype and mosaicism. They look fine. FISH images can have better resolution as it is difficult to see the signals. Please provide more information about the bioinformatic processing of ES data (variant processing, annotation, filtering, etc). Provide also the versions of the softwares and remember to cite them. - Please avoid abbreviation in the title. e.g DSD. - FISH images: It is difficult to see green and red signals. Do you have more closer images or perhaps higher resolution images? - Have you analyzed the 55 genes only for SNPs and indels? Have you checked copy number variation in ES? - Have you checked other unbalanced and balanced chromosomal events?

Conflicts of interest

Do you have any conflicts of interest here? no