Consecutive medical exome analysis at a tertiary center: Diagnostic and health-economic outcomes.

The utility of whole exome analysis has been extensively demonstrated in research settings, but its clinical utility as a first-tier genetic test has not been well documented from diagnostic and health economic standpoints in real-life clinical settings. We performed medical exome analyses focusing on a clinically interpretable portion of the genome (4,813 genes) as a first-tier genetic test for 360 consecutive patients visiting a genetics clinic at a tertiary children's hospital in Japan, over a 3-year period. Bioinformatics analyses were conducted using standard software. A molecular diagnosis was made in 171 patients involving a total of 107 causative genes. Among these 107 causative genes, 57 genes were classified as genes with potential organ-specific interventions and management strategies. Clinically relevant results were obtained in 26% of the total cohort and 54% of the patients with a definitive molecular diagnosis. Performing the medical exome analysis at the time of the initial visit to the tertiary center, rather than after visits to pertinent specialists, brain MRI examination, and G-banded chromosome testing, would have reduced the financial cost by 197 euros according to retrospective calculation under multiple assumption. The present study demonstrated a high diagnostic yield (47.5%) for singleton medical exome analysis as a first-tier test in a real-life setting. Medical exome analysis yielded clinically relevant information in a quarter of the total patient cohort. The application of genomic testing during the initial visit to a tertiary medical center could be a rational approach to the diagnosis of patients with suspected genetic disorders.

Medical genetics and genomic medicine in Japan.

Since 1961, all Japanese citizens have belonged to one of the available medical care insurance systems. This "universal care" system has contributed to the maintenance of health: the life expectancy at birth was 84 years in 2016, and the infant mortality rate (the number of infants dying before reaching 1 year of age) was 2.0 per 1,000 live births, which is one of the lowest rates in the world. The Japanese government initiated the National Program on Rare and Intractable Diseases in 1972. This program has promoted research and expanded support for patients with rare and intractable diseases. Registered patients are eligible for a subsidy scheme that helps to cover medical care costs. Among the 331 diseases that are currently included in this program, more than half of the diseases are Mendelian disorders. The National Program on Rare and Intractable Diseases has fostered research in medical genetics in Japan and many causative genes for Mendelian diseases have been identified by Japanese geneticists. Recently, the Japanese government has determined to support several genomic medicine initiatives including the undiagnosed disease program (Initiative on Rare and Undiagnosed Diseases) and pathogenic variant databases.