Five independent mutations in the hypoxanthine guanine phosphoribosyltransferase (HPRT) gene were identified in a partially HPRT deficient patient with gout and in four Lesch-Nyhan patients. Using the polymerase chain reaction (PCR) technique coupled with direct sequencing, the nucleotide sequences of the entire HPRT coding region amplified from the cDNA and also of each exon amplified form the genomic DNA were analyzed. Three independent point mutations in the coding region were detected in the partially HPRT deficient patient (Case 1) and in two Lesch-Nyhan patients (Case 2 and 3), resulting in single amino acid substitutions. The family study of Case 3, utilizing a PvuII restriction site created in the mutant gene, indicated that the mother was a heterozygote, and a sister and a fetal brother had inherited the normal HPRT gene from the mother. In two other mutants causing Lesch-Nyhan syndrome, a portion of the HPRT gene was deleted, and RNA splicing was missing in both mutants. A 4-bp deletion at the 5' end of exon 4 resulted in formation of three different types of abnormal mRNA (Case 4). The other mutant (Case 5) produced abnormal mRNA including 26 bp of intron 8 instead of the deleted 58 bp at the 5' end of exon 9, because of a 74-bp deletion from intron 8 to exon 9.

A fetus with midgut volvulus is described. The mother had developed polyhydramnios, and the fetus was found by sonography to have dilated fluid‐filled structures compressing the chest in the upper abdomen. Percutaneous aspiration of the upper abdominal mass was performed to identify the content and know whether decompressing the chest would be beneficial. The removal of meconium‐stained fluid accomplished an improvement of the fetal biophysical profile. The infant was delivered by low transverse cesarean section, and survived with immediate removal of the fluid in the abdominal mass and ventilatory therapy.

Recently, molecular genetic techniques have been rapidly incorporated into routine clinical as well as laboratory medicine, and genetic diseases including inborn errors of metabolism have come to be diagnostically viewed as changes in DNA. Molecular genetic techniques have the advantage that rapid and accurate analysis can be made with a small amount of samples in comparison with analysis at the protein level by conventional biochemical techniques. They are, therefore, clinically used today not only for the diagnosis of various genetic diseases but also for the detection of infection, including viral infections, in the outpatient clinic. They have also been applied to fetal diagnosis, and are bringing about major changes in prenatal medicine.

Data were tabulated and compared for cases involving prenatal diagnostic procedures performed in the 8 years between January 1985 and December 1992. Of a total of 2781 pregnancies, 2546 cases (91.5 per cent) were diagnosed by amniocentesis, and 235 (8.5 per cent) by chorionic villus sampling (CVS). These findings reflect the fact that amniocentesis has taken deep root as the prenatal diagnostic procedure widely acknowledged by society, whereas even the existence of CVS has yet to be generally recognized. Analysis of our clinical and laboratory results and complication rates, however, suggests that CVS is a safe and accurate alternative to amniocentesis which should and can be positively presented to all patients who are candidates for prenatal diagnosis.