[DNA diagnosis: its induction, problem and future--with special reference to congenital goiter]

PCR technique is a powerful tool for genetic analysis of various diseases including infectious diseases, inherited diseases and malignant tumors. Some of our experiences and problems in gene level diagnosis using mainly the PCR technique newly introduced to our clinical laboratory were discussed. A case of congenital goiter in which the analysis at the gene level was the first demonstration of a mutation associated with the abnormal expression of the thyroglobulin gene in man, is also presented. The direct demonstration from the sputum of the presence of M. tuberculosis DNA by PCR will be a great benefit to the clinician in the diagnosis and treatment of tuberculous infection. At present, it is possible to report the results within 2 days from the submission of samples, but further considerations on the sensitivity and specificity are required. The clinical laboratory will be required to accumulate sufficient knowledge of gene level analysis of various disease conditions and master the techniques.