It is possible that entire genes may not be captured and sequenced in a particular patient, though in general we expect that there are only small portions of different genes not amenable to evaluation. Some exons have low or no coverage because probes have not been designed or are unavailable for these regions. It may be challenging to obtain usable sequence data for some regions. To check coverage of specific genes via exome or genome sequencing, visit the XomeDx^® Slice Tool.