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Biomedical subjects

Peter M Schneider

Publications and source records attributed to Peter M Schneider.

6 recordsLinked to original sources
PubMed2003

Comparative analysis of short tandem repeats and single nucleotide polymorphisms on the Y-chromosome in Germans, Chinese and Thais.

We have typed genomic DNA samples from 95 individuals from Western Germany, 78 individuals from Bangkok/Thailand and 56 individuals from Chengdu/China for 11 Y-chromosomal diallelic polymorphisms and eight short tandem repeat (STR) systems. For single nucleotide polymorphism (SNP) analysis, a rapid method was applied using the single base extension technology (minisequencing) in combination with capillary electrophoresis. PCR products for SRY-8299, Tat, SRY2627, 92R7, SRY1532, M9, M13, M17/M19 and M20 were pooled and used as templates for the commercially available SNaPshot kit. In addition to these ten SNPs we also tested the Y-chromosomal diallelic Alu repeat insertion DYS287 (YAP) by agarose gel electrophoresis as well as the Y-chromosomal STR systems DYS19, DYS389I+II, DYS390, DYS391, DYS392, DYS393 and DYS385 by fluorescent multiplex fragment analysis. Among the 11 diallelic SNP/Alu systems, only six were found to be polymorphic in the three population samples. From these a total number of seven different haplogroups could be identified in the three populations. Of these, five haplogroups were present in Germans, five in Thais, and only two in Chinese. These haplogroup trees clearly represent population-specific structures. Haplogroup 26 is represented at a high frequency in the Thai and Chinese populations whereas it is absent in Germans. The Y-STR data confirm a haplogroup-specific distribution of Y-STR haplotypes. Only a few cases of identical STR haplotypes in the same SNP haplogroups were detected in each of the three populations studied.

China↗
PubMed2003

Expert witness in paternity testing in Germany.

In Germany, paternity testing can be ordered by a judge as well as by private persons. In the case of private counselling, the expert has the duty to inform the parties on all medical, legal and ethical aspects. Informed consent must be given by each individual included in an exploration of family relationships. Due to the rapid progress of DNA typing in even minute amounts after polymerase chain reaction amplification, genotypes of short tandem repeat systems can be elicited by extraction from single cells. Therefore, the number of unlawful investigations of paternal relationships is steadily increasing. Here the requirements for paternity testing laboratories and sanctions for unlawful exploration of a person's genotypes are discussed. A new Federal law should be drafted.

DNA Fingerprinting↗
PubMed2002

Paternity Testing Commission of the International Society of Forensic Genetics: recommendations on genetic investigations in paternity cases.

The International Society for Forensic Genetics (ISFG) has established a Paternity Testing Commission (PTC) with the purpose of formulating international recommendations concerning genetic investigations in paternity testing. The PTC recommends that paternity testing be performed in accordance with the ISO 17025 standards. The ISO 17025 standards are general standards for testing laboratories and the PTC offers explanations and recommendations concerning selected areas of special importance to paternity testing.

Equipment and Supplies↗
PubMed2002

Differential genetic determination of immune responsiveness to hepatitis B surface antigen and to hepatitis A virus: a vaccination study in twins.

BACKGROUND: The course of viral hepatitis is thought to be affected by genetic host variability and, in particular, by genes of the major histocompatibility locus. Hepatitis A and B vaccination is a useful model to study the effect of host factors on the immune response to viral antigens. We aimed to assess the heritability of the HBsAg (anti-HBs) and anti-hepatitis A virus (anti-HAV) immune response and to estimate the effect of the HLA-DRB1 locus and other genetic loci unlinked to HLA. METHODS: We did an open prospective study and vaccinated 202 twin pairs with a combined recombinant HBsAg/inactivated hepatitis A vaccine. We measured antibodies to HBsAg and HAV and determined HLA-DRB1* alleles. Heritability was calculated based on variance of antibody response within pairs. Model-fitting analyses were done to analyse genetic and environmental components of vaccine responses. FINDINGS: Anti-HBs and anti-HAV showed heritabilities of 0.61 (95% CI 0.41 to 0.81) and 0.36 (-0.02 to 0.73), respectively. For the anti-HBs immune response, 60% of the phenotypic variance was explained by additive genetic and 40% by non-shared environmental effects. The heritability of the HBsAg vaccine response accounted for by the DRB1* locus was estimated to be 0.25, leaving the remaining heritability of 0.36 to other gene loci. INTERPRETATION: Genetic factors have a strong effect on the immune response to HBsAg. Although genes encoded within the MHC are important for this immune response, more than half the heritability is determined outside this complex. Identification of these genes will help us to understand regulation of immune responses to viral proteins.

Adolescent↗
PubMed2002

C4A deficiency and nonresponse to hepatitis B vaccination.

BACKGROUND/AIMS: Hepatitis B vaccination failure has been linked to the presence of certain human leukocyte antigen class II alleles. However, the functional background of these associations has remained unclear. Complement component C 4 is encoded within the major histocompatibility complex and is essential for classical pathway activation. METHODS: Healthy individuals (n=4269) were vaccinated in a prospective trial with Engerix B. Nonresponse was classified as anti-HBs<10 U/l after the last vaccination. Seventy-three nonresponders (NR) (1.7%) were identified. For comparison 53 responders (R) (anti-HBs>10 IU/l) were drawn randomly from the same cohort. C4 allotyping was carried out by high-voltage agarose gel electrophoresis and C4alpha-chain typing using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. C4 gene deletions (C4Del) were studied by Southern blot. RESULTS: C4AQ0 alleles were observed in 45/73 (62%) NR compared to 17/53 (32%) R (P=0.001). C4ADel was observed in 24/73 (33%) NR and in 6/52 (12%) R (P=0.006). C4AQO alleles were present in 21/49 (43%) NR without C4Del compared to 10/46 (22%) in R without C4Del (P=0.031). In a logistic regression with DRB1*0301, DRB1*07, DRB1*1301 and C4AQ0 all except for DRB1*0301 showed a significant association. CONCLUSIONS: C4AQ0 shows a DRB1*0301 independent association with vaccine failure. C4AQ0 alleles probably contribute to inefficient complement activation and failure of B cells to secrete anti-HBs.

Adult↗