小児神経疾患と遺伝子

For children with neurological disorders, we are often unable to identify any abnormalities during the examination based on the blood test, CT/MRI, EEG, EMG, etc. In such cases, it becomes necessary to check for congenital genetic anomalies, especially when two or more symptoms involving external malformation, organ malformation, and defect in eyesight or hearing ability are found. Under clinical settings, the G-banding stain is the first such test to be conducted. Although the cost is covered by insurance and the test can be used to examine all of the chromosomes, it is only capable of detecting comparatively large deletions and duplications. The FISH method, however, has far higher sensitivity compared to the G-banding in terms of identifying deletions and duplications. Unfortunately, since it utilizes specific DNA probes, it cannot be used without first specifying a particular target disease. Moreover, even if the correct target disease is chosen, this test consistently produces numerical abnormalities. Therefore, we may find it best to use the microarray-based comparative genomic hybridization （array CGH）. This test makes it possible to analyze an entire genome domain, and the sensitivity is much higher than that of G-banding. In recent years, a large number of microdeletions have been found by this method. However, this method is expensive because it is not covered by insurance, and structural anomalies without abnormalities in the copy number are also undetectable. In addition, although analyses using next-generation sequencers are becoming more widespread, this test is still performed in the laboratory. At present, various gene abnormalities are being identified in pediatric neurological disorders through the progress of gene-analysis technology. Therefore, our knowledge of the genetic diseases we analyze is increasing rapidly, and we frequently need to consult with genetic specialists. Unfortunately, since the types of examinations available in clinical settings are still somewhat restricted, we hope that the costs of a microarray analysis suitable for these types of genetic screening will soon be covered by insurance.