However, we observed a mutual interaction between genetic testing and TEM in one patient with Kartagener syndrome and VUS in DNAH5, in whom the observed ultrastructural defect (MTD + IDA) did not match the expected outcome and triggered genetic reanalysis and, subsequently, detection of homozygous VUS in CCDC40 that would otherwise have been missed. The gene discussed is CCDC40; the disease is Kartagener Syndrome.