Genetic Testing for Kabuki Syndrome
In August 2010, researchers at the University of Washington (Ng et. al., 2010) discovered the MLL2 genei mutations responsible for approximately 2/3rds of the cases of Kabuki Syndrome. As a result of this finding, many laboratories are now offering blood tests to confirm if an individual carries this gene mutation. Some of these labs are also offering parental and prenatal testing as well. The number of labs offering these tests continues to grow. The National Center for Biotechnology keeps a current database of laboratories offering this test.
If you are interested getting tested, you can ask your geneticist or another specialist to order the tests, perform the blood work (about 5 cc’s of blood draw) and have it sent to one of these labs. Turnaround time to receive results is approximately 6-8 weeks. The test is called MLL2 Full Gene Sequencing and the test code is SMLL2. If applicable, it is advisable to call your insurance company to see if the test will be covered. All insurance companies are different, but many insurers cover this test because it is diagnostic. CPT codes are: 83891 (x1), 83894 (x1), 83898 (x76), 83904 (x152), 83909 (x152), 83912 (x1) and cost is approximately $2,000 to $3,000 US dollars (if not covered by insurance) for the first individual. Once a mutation is identified, other family members can be tested and prenatal testing can be done. Cost for testing another individual for a particular mutation is $390 and cost for prenatal testing for this mutation is $590. In Canada and other countries, the testing may not yet be available, but there have been situations where a geneticist may send the samples to the U.S. for testing.
In considering Full Gene Sequencing testing, it is important to remember that the area of exomei microarray analysis and gene sequencing is brand new and therefore information is continually coming available. For instance, while the University of Washington study indicated that MLL2 gene mutations are responsible for approximately 70% of cases, a new study by Milunsky et. al. at Boston University School of Medicine, suggests that the MLL2 mutation may be responsible for only about 44% of cases and additional gene(s) yet to be discovered may account for remaining cases.
Given the newness of this research, we should keep in mind that while genetic blood testing is a valuable tool in diagnosis, a clinical diagnosis from a geneticist based on the cardinali features of Kabuki Syndrome should still be a family’s first step. Even if an individual blood test comes back negative for an MLL2 mutation, professionals and families might still have reason to believe that the child has Kabuki Syndrome. Also, by opting into a research portion of these tests, individuals are providing samples to help further learning about the syndrome that will benefit the broader Kabuki population.
Finally, while receiving an accurate diagnosis is important, focusing on proactively addressing medical and developmental issues through early intervention and consultation with specialists is of utmost importance in making sure the individual achieves their own best health and highest potential.