On August 15, 2010 researchers at the University of Washington announced the discovery of the MLL2 genei mutations responsible for approximately 75% of individuals with Kabuki Syndrome. The scientists used a "second generation" technique to examine only the protein-coding gene portion of the human genome, called the exome. Since the exome constitutes only 1 - 2% of the human genome, the cost and time requirement has been greatly reduced, making it more plausible to look for gene mutations.
There are different reasons why a gene may have a mutation. In the case of Kabuki, the MLL2 gene mutations were found to be due to either nonsense or frame-shift mutation which resulted in a shortened, nonfunctional protein. To help families better understand the basics of the discovery please see Understanding the Genetics of Kabuki.
It is speculated that Kabuki is a heterogeneous syndrome, meaning that multiple genes could potentially be involved. It is hoped that with continued analysis, other genes will be discovered.