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Robert E Wenk

Publications and source records attributed to Robert E Wenk.

10 recordsLinked to original sources
PubMed2006

Maternal typing and test sufficiency in parentage analyses.

BACKGROUND: The contribution of maternal typing to paternity analysis was evaluated to determine how many additional loci to study in one-parent cases. STUDY DESIGN AND METHODS: Four groups underwent paternity analyses with an eight-locus test battery. Files of 25 case trios were retrieved, in which alleged fathers had achieved paternity indices of greater than 100 ("included trios"). Maternal types were omitted and the cases were reanalyzed ("included duos"). Mother-child pairs of the cases were then coupled with unrelated men ("excluded trios"), and the cases were analyzed. Maternal types were omitted from the excluded trios and cases were reanalyzed ("excluded duos"). RESULTS: Paternity indices of men in included duos were markedly reduced when compared to included trios; odds were sufficiently low in 9 of 25 men that paternity remained in doubt. After omission of maternal phenotypes, excluded duos exposed 33 percent fewer genetic inconsistencies than excluded trios; 5 of 25 men in excluded duos demonstrated less than two genetic inconsistencies and 1 man had none. The specific probabilities of paternity exclusion in motherless cases averaged 61 percent per locus of those in case trios. One random man in 52 duos was not excluded by the eight tests versus 1 in 417 trios. CONCLUSIONS: Omission of maternal typing from eight common microsatellite paternity tests reduced conclusive evidence for or against paternity by 30 to 40 percent. False inclusion of random men is an important failing of tests in motherless cases. Cases involving one parent and child (e.g., in immigration) would require examination of an additional five similar loci to compensate for absent maternal data. A change in standards is suggested.

Fathers↗
PubMed2005

The specific power of parentage exclusion in a child's blood relatives.

BACKGROUND: The impersonation of parent and child by two other blood relatives is an important problem in parentage analysis involving potential immigrants. STUDY DESIGN AND METHODS: A statistic (AR) is proposed, based on the specific power of exclusion of paternity, which describes the ability of a child's test results to demonstrate evidence of nonparentage under the hypothesis that an ostensible parent is actually an older sibling. A case illustrates the value of A(R): a woman and her two alleged children were typed at 3 variable number of tandem repeat (VNTR) loci after 18 short tandem repeat (STR) loci initially showed strong evidence of the woman's maternity of one child and her exclusion from parentage of the second. AR and 1 - AR were calculated from the STR types of the first child. RESULTS: The woman was excluded from maternity of both children with the additional VNTR tests. Given the 18 STR test findings of the first child, the probability was 12 percent that there would be no inconsistencies with parentage in a sibling pretending to be a parent. CONCLUSION: The value 1 - AR, siblings not excluded from parentage, explains how a seemingly large number of examined loci can fail to reveal even one genetic inconsistency if two siblings have posed as parent and child. Approximately 25 STR loci appear necessary to achieve 95 percent confidence of detecting at least one genetic inconsistency indicative of nonparentage.

Adult↗
PubMed2004

Testing for parentage and kinship.

PURPOSE OF REVIEW: Parentage analyses are of interest to workers in health care, law enforcement, immigration and other fields. This review describes recent applications, technical advances, and quality improvements. RECENT FINDINGS: Mutations at short tandem repeat sequence loci confound interpretations of genetic data used to assess all blood relationships. Rates of the usual mutation type (change in repeat number) are probably related to specific alleles at each locus as well as to allele length, locus, and gender. Short tandem repeat sequences have relatively limited information content per locus. Intermediate tandem repeat sequence loci may be better. In immigration proceedings, probabilities can be calculated for excluding parentage in blood relatives who might impersonate the biologic parent. Unrelated immigrants from a subpopulation may appear to be related, but it is now possible to statistically determine the effect of population substructure on kinship determinations. In forensic analyses, sex chromosomal (X and Y) short tandem repeat sequences and mitochondrial DNA sequence variations have helped identify the parental lineages of human remains. Recent laboratory quality improvements include a way to estimate the frequency of common mother-child specimen mislabeling in routine paternity cases. In prenatal testing there are now methods for avoiding erroneous assignment of contaminant maternal alleles to the fetus. False paternity exclusions can be avoided by adhering to a standard of the American Association of Blood Banks requiring duplicate DNA isolation and retesting of excluded men. SUMMARY: Laboratory technology and quality have advanced, but genetic tests with greater information content are needed. Better communication is highly desirable between persons requesting tests and parentage laboratories.

DNA Fingerprinting↗
PubMed2003

Molecular evidence of Munchausen syndrome by proxy.

Many perpetrators of Munchausen syndrome by proxy present bloodstained materials as counterfeit evidence of proxy hemorrhage. Although blood grouping may show that the blood is not the proxy's, DNA typing may specifically identify the blood's source. A mother claimed that she alone had witnessed gastrointestinal bleeding of her son and presented bloodstained towels as evidence. Several clinical investigations had failed to reveal a bleeding source. I compared the DNA types of the bloodstains and the child's buccal cells. The bloodstain and epithelial cells differed at 4 of 8 microsatellite loci and at the amelogenin locus. The blood and buccal cells shared 1 allele at every locus, suggesting that their sources were closely related. The probability that the source of the blood was maternal was 0.9915 (prior probability, 0.5). I recommend DNA matching in suspected cases of Munchausen syndrome by proxy whenever blood is presented as evidence.

DNA↗
PubMed2002

Coagulant stability and sterility of thawed S/D-treated plasma.

BACKGROUND: Units of frozen S/D-treated plasma (SDP) must be transfused within 24 hours after thawing. To avoid waste, an attempt was made to determine how long SDP could be therapeutically effective after thawing and storing it at 20 degrees C. STUDY DESIGN AND METHODS: The microbiologic safety and the activity of labile coagulation factors were evaluated in units stored at 20 degrees C of thawed SDP units and FFP within 24 hours of collection (FFP24). Five SDP and FFP24 samples of each ABO blood group were cultured and assayed for coagulation factors daily over 5 days. Assays included FV, FVII, FVIIa, FVIII, F IX, FXI, protein S, antiplasmin, fibrinogen, prothrombin times (PTs), and activated partial thromboplastin times (aPTTs). RESULTS: None of the 80 bacterial cultures demonstrated growth under either aerobic or anaerobic conditions. FV, FVIII, F IX, FXI, fibrinogen, and the aPTT appeared to be stable in both thawed FFP24 and SDP. The PT increased slightly in thawed FFP24 and insignificantly in SDP. FVII decreased slightly in FFP24 but remained in the normal range, and FVIIa was low and constant. FVII was increased in SDP and FVIIa was markedly increased. Protein S decreased from initial normal values in FFP24 to very low values. Protein S was very low immediately after thawing in the SDP and continued to decline. Antiplasmin was normal and stable in thawed FFP24 but was low in SDP and remained constant after thawing. CONCLUSION: Sterile SDP that is stored at 20 degrees C provides sufficient coagulant activity of labile FV and FVIII to transfuse it for up to 5 days after thaw. Caution is warranted by decreases in Protein S and antiplasmin, clinical evidence of coagulopathy in some recipients of SDP, and a recent manufacturer's warning.

Blood Coagulation↗