A novel dimorphism in the human SRY gene: usefulness in human migration studies.

A nucleotide polymorphism of C or T was detected at position 465 in the sex-determining region Y (SRY) gene. To evaluate the utility of this dimorphism in human population studies, the frequency and the frequency of the haplotype combined with the two polymorphic loci YAP and M9 were examined in a total of 130 unrelated Japanese and 130 unrelated German males. The T nucleotide was found in 24.6% (32/130) of the Japanese but not in any of the 130 German males. Accordingly, four of the eight possible combination haplotypes of SRY/YAP/M9 were identified in the Japanese population, but one of the four haplotypes comprising SRY(T) was absent in the German samples. This suggests that the C to T transition may be more recent than the YAP insertion or the M9 transversion and the change might have occurred in an ancestral Asian population. These results imply that the dimorphism at the SRY gene is one of the Y-linked markers useful for human population studies and also for ethnic identification of forensic samples.

Narrative approach to ethics education for students without clinical experience.

Niigata University School of Medicine has provided three courses in which medical ethics (ME) is taught to students who have little or no clinical experience. To evoke student's imagination, we have developed a "narrative approach" to learn ME using cases. Prior to a case analysis, students are required to exchange their own life history regarding the core issues in the case. A case is presented not only in the traditional form of vignette, but also in the form of narrative. In the narrative, the case is a story composed of personal narratives, collected and edited from diaries, letters, interviews of persons involved. Our experience suggests that the principle-based reasoning using simple vignettes is often hardly accomplished by students. However, the narrative approach was found to be useful since students can: (1) gain more accurate and wide comprehension of medical and psycho-social aspects of the case; (2) grasp the nature and the history of the conflicting views among persons in the case; (3) find more easily any method for dealing with and settling problems; and (4) exchange viewpoints with patients and their family.

[Haplotype analysis using two tetrameric loci within the vWF gene: its frequency in Japanese and application in forensic medicine].

The potential usefulness of a haplotype analysis in forensic investigations was examined, as a haplotype produces more variation than an allotype. Two tetrameric repeat loci, vWF-k and vWF-p, were chosen as a haplotype probe, these being located within approximately 700 bp of intron 40 of the von Willebrand factor gene. Their polymorphisms were determined by PCR for DNA obtained from a total of 57 families and haplotypes were constructed on the basis of the family data. As many as 29 haplotypes were identified of 116 unrelated individuals included in the families. Its heterozygosity and polymorphism information content were 0.948 and 0.921, respectively. Among the 116 individuals, 72 were distinguished using the simply combined genotyping of vWF-k and vWF-p. On the other hand, 77 diplotypes were determined with the haplotype analysis. This indicates the value of such testing in personal discrimination, especially in cases where there is family information. The present paper also describes case studies, which include a successful application of this haplotype analysis to the individual identification of a decomposed forensic sample.

Recurrent placental site trophoblastic tumor of the uterus: clinical, pathologic, ultrastructural, and DNA fingerprint study.

Placental site trophoblastic tumor is a rare disease. Most benign cases of this disease show a few mitotic figures of the tumor while recurrent cases usually have more than 5 mitoses per 10 high-power fields. The present case was primarily treated by hysterectomy and chemotherapy and had 2 mitoses in 10 high-power fields. After 1 years and 4 months of therapy the patients was diagnosed as ovarian metastasis because of gradually increasing serum beta-human chorionic gonadotropin (hCG) level and abnormally high fluid levels of beta-hCG and human placental lactogen (hPL) punctured from her cystic ovarian tumor. This recurrent case was further treated with another regimen of chemotherapy for 7 courses, and the serum beta-hCG level had decreased at present. This report describes the recurrent case and discusses the histology of a few mitotic figures, electron microscopic findings, and results of the DNA fingerprint analysis of the primary tumor.

Three short tandem repeat loci in Japanese population.

Allele frequencies of three short tandem repeat loci, vWF, TH and GCG, were examined for 210 unrelated Japanese individuals. Eight alleles were identified with PCR and gel electrophoresis for vWF, 7 for TH and 13 for GCG, indicating that these loci are highly polymorphic. Combined discrimination power of the 3 STRs was 0.995. These results imply that the loci are useful as probes for the identification of Japanese individuals. Thus, we applied the probes to the identification of a forensic specimen that was decomposed severely. The vWF and TH probes successfully gave clear bands in gel electrophoresis, but GCG failed to be typed because of a lot of shadow bands. The results suggests the usefulness of at least the former two probes in forensic studies.

Sex typing of forensic DNA samples using male- and female-specific probes.

Forensic DNA samples have been examined to ascertain the feasibility of a sex-typing procedure that we have recently developed. This uses two sets of primers complementary to the DXZ4 and SRY genes for polymerase chain reaction (PCR). PCR target in the DXZ4, an 80-bp sequence within the 130-bp fragment specific to females, is generated from inactive chromosome X by the DNA digestion with a methylation-sensitive restriction enzyme, HpaII. Therefore, the DXZ4 amplification and subsequent agarose gel electrophoresis detect the 80-bp fragment from female DNA. On the other hand, the SRY probe identifies a male-specific sequence on chromosome Y. Testing DNAs from fresh Turner's blood and from postmortem tissues exhibited band-signals confirming the sex identification. Degraded DNAs isolated from severely decomposed specimens were also identifiable when high-molecular-weight DNA was isolated before the assay. This demonstrates the usefulness of this method in forensic identification.

Ribosomal ribonucleic acid (rRNA) gene typing for species identification.

Deoxyribonucleic acid (DNA) typing of ribosomal ribonucleic acid (rRNA) genes was performed with a polymerase chain reaction (PCR) assay for species identification. A variable region of the 28S ribosomal RNA gene was amplified with primers complementary to flanking sequences phylogenetically well conserved. The products of twelve animal DNAs (human, Japanese monkey, dog, cattle, pig, cat, rabbit, mouse, rat, chicken, frog, and fish) were separated by polyacrylamide gel electrophoresis, each revealing a few bands ranging from 150 to 100 base pairs. The band patterns obtained from each DNA sample differed in number and size, which indicates the applicability of the method to species identification. Samples containing either as little as 1 pg of DNA or degraded DNA of 0.2 to 0.5 kb in length were able to give detectable bands. Postmortem human tissue DNAs were tested as an example. They showed a pattern identical to the human control one, which was distinct from those of the other animals examined.

DNA fingerprinting by means of a nonradioactive probe of sulfonated DNA.

A DNA fingerprinting technique that uses a cold sulfonated DNA probe is described. DNA was extracted from blood samples of a family, who were subjected to DNA fingerprinting. The restriction fragments that were hybridized with the probe were colorimetrically detected by an enzyme immunoassay. For DNA detection and labeling a commercially available kit was employed. The sensitivity of this fingerprint detection method has been proven comparable to detection by the radioactive method, and hence is easier to use in conventional laboratories.