to recurrent deletion events. We also identified small deletions in TBX5, a gene known to cause Holt-Oram syndrome45 (a disorder characterized by upper limb abnormalities and congenital heart defects; OMIM #142900). We found that 7 of 15 samples predicted to harbor a TBX5 event were fetal samples, a rate significantly greater than the background proportion of fetal samples (13.4%, p = 0.0019), consistent with the observations that TBX5 mutations can result in prenatal abnormalities detectable by ultrasound46.
