Paternity testing after pregnancy termination using laser microdissection of chorionic villi

We report an unusual case of paternity testing from residues of chorionic villi 5 weeks after pregnancy termination. The autopsy of a 32-year-old female homicide victim revealed the presence of intact chorionic villi at the former placenta implantation site. Fetal cells were selectively isolated by laser-induced microdissection of the remaining villi to avoid contamination with maternal DNA. Simultaneous amplification of 12 STR loci in 2 PCR reactions resulted in a combined probability of paternity of 99.94%. This case demonstrates that laser-assisted microdissection and multiplex STR typing provide tools for paternity testing performed on endometrial mucosa long after the product of conception was removed by therapeutic abortion. Received: 2 May 2000 / Accepted: 7 November 2000     

Paternity evaluation in cases lacking a mother and nondetectable alleles

In parentage testing the formulae for computing paternity index and exclusion probability generally ignores the presence of nondetectable alleles at the loci tested. In contrast, it is now known that even when paternity testing is done with hypervariable DNA markers, nondetectable alleles should not be ignored. This work presents simple formulae needed with this consideration, to analyze paternity evaluation from DNA markers in cases where the mother of the disputed child is unavailable for testing. It is shown that even a modest frequency of nondetectable alleles (e.g., 2–5% per locus) may have a substantial impact on the paternity index when the child and/or the alleged father exhibits a single-banded DNA profile at a locus. Use of such formulae can generate a high probability of exclusion and a high paternity index when multiple independently segregating hypervariable DNA markers are used.     

Structure of new mutations in 2 STR systems

Isolated father/child mismatches in cases with a high probability of paternity (W > 99.9%) have been investigated using short tandem repeat (STR) systems. According to the high probability of paternity new mutations could be assumed in these cases. A new mutation could be observed in 3 cases using the STR system HumACTBP2. Two of these cases showed a deletion and 1 case an insertion of 1 repeat (AAAG-motif) which could be verified by sequencing. In another paternity case a new mutation - 1 - repeat insertion (TCTA-motif) - in the HumVWA system was detected and verified by sequencing. These findings led to a new mutation rate of 0.7% (n = 453 meioses) for HumACTBP2 and 0.2% for HumVWA (n = 484 meioses).     

Exclusion probabilities and likelihood ratios with applications to kinship problems

In forensic genetics, DNA profiles are compared in order to make inferences, paternity cases being a standard example. The statistical evidence can be summarized and reported in several ways. For example, in a paternity case, the likelihood ratio (LR) and the probability of not excluding a random man as father (RMNE) are two common summary statistics. There has been a long debate on the merits of the two statistics, also in the context of DNA mixture interpretation, and no general consensus has been reached. In this paper, we show that the RMNE is a certain weighted average of inverse likelihood ratios. This is true in any forensic context. We show that the likelihood ratio in favor of the correct hypothesis is, in expectation, bigger than the reciprocal of the RMNE probability. However, with the exception of pathological cases, it is also possible to obtain smaller likelihood ratios. We illustrate this result for paternity cases. Moreover, some theoretical properties of the likelihood ratio for a large class of general pairwise kinship cases, including expected value and variance, are derived. The practical implications of the findings are discussed and exemplified.     

Prenatal paternity testing with DNA analyses

Summary Two PCR amplified loci and 3 single locus DNA probes were applied in a paternity case in which a married woman became pregnant after being raped. DNA analysis were performed using samples from the woman, her husband and amniotic fluid cells taken during the 16th week of pregnancy. The combined probability of paternity for her husband was calculated as 0.999997107. The application of PCR analyses and single locus DNA probes were considered to be extremely informative in prenatal paternity testing.     

Setting the boundaries of prior influence on kinship relation testing: the case of many hypotheses

Kinship relation and, in particular, paternity probability estimation using a Bayesian approach require the input of a priori probabilities of different hypotheses. In practical case work, a priori probabilities or priors, for short, must often be estimated using only common sense and symmetry arguments because in most cases, there is no evidence-based information on which the priors may be determined. In contrast to the accuracy of the likelihood probabilities or the likelihood ratios, the precision of the priors is usually very poor. Thus, a quantitative estimation of the priors’ influence on the paternity probability is desirable. This article presents exact formulae to define sharp minimum and maximum boundaries of posterior probabilities as a function of prior boundaries which may be applied in kinship cases with varying numbers of hypotheses and also presents two case examples.     

Calculation of percentage of cases on file with an unnamed father in 100 one-man and 100 two-man cases (filiation cases) from South-West Germany in 1976–1981

Summary Applying the formula of Schulte-Mönting and Hummel to 100 one-man affairs (filiation cases) in South-West Germany between 1979 and 1981 gave a realistic prior probability of paternity of 0.837±0.0372. This means that in approximately 83.7% of all one-man affairs the man named by the mother to be the father of her child is indeed the father.For two-man affairs a realistic prior probability of paternity of 0.863±0.0369 was calculated on the basis of 100 two-man affairs in South-West Germany between 1976 and 1981. In other words, there is a probability of about 86.3% that a non-excludable man—irrespective of other factors—in a two-man affair is the real father of the child. In approximately 13.7% of two-man affairs neither the defendant nor the witness is the father, but a third unknown person. In about 85.7% of the two-man affairs in which a father of the child was named the defendant is in fact the father and in 14.3% the witness is the father.     

DNA investigations on fetal material from paternity cases

Summary Three paternity cases have been investigated where DNA was extracted from fetuses (age: 8–10 weeks old) after interruption of pregnancy. In each case it was possible to clearly identify the putative father using 5 or 6 single locus probes (SLP's). Fetal bands (SLP) could be clearly identified from mixtures of placental and fetal DNA by comparison with the maternal and paternal bands. However, it was very difficult to resolve the fragment patterns of tissue mixtures with one multi locus probe (MLP), because of band overlap. Another advantage of using SLP's was that biostatistical calculations could be carried out and very informative Essen-Möller values for the probability of paternity were obtained.     

Fetal male lineage determination by analysis of Y-chromosome STR haplotype in maternal plasma

The aim of this study is to determine the fetus Y-STR haplotype in maternal plasma during pregnancy and estimate, non-invasively, if the alleged father and fetus belong to the same male lineage. The study enrolled couples with singleton pregnancies and known paternity. All participants signed informed consent and the local ethics committee approved the study. Peripheral blood was collected in EDTA tubes (mother) and in FTA paper (father). Maternal plasma DNA was extracted by using NucliSens EasyMAG. Fetal gender was determined by qPCR targeting DYS-14 in maternal plasma and it was also confirmed after the delivery. From all included volunteers, the first consecutive 20 mothers bearing male fetuses and 10 mothers bearing female fetuses were selected for the Y-STR analysis. The median gestational age was 12 weeks (range 12–36). All DNA samples were subjected to PCR amplification by PowerPlex Y23, ampFLSTR Yfiler, and two in-house multiplexes, which together accounts for 27 different Y-STR. The PCR products were detected with 3500 Genetic Analyzer and they were analyzed using GeneMapper-IDX. Fetuses’ haplotypes (Yfiler format) were compared to other 5328 Brazilian haplotypes available on Y-chromosome haplotypes reference database (YHRD). As a result, between 22 and 27 loci were successfully amplified from maternal plasma in all 20 cases of male fetuses. None of the women bearing female fetuses had a falsely amplified Y-STR haplotype. The haplotype detected in maternal plasma completely matched the alleged father haplotype in 16 out of the 20 cases. Four cases showed single mismatches and they did not configure exclusions; 1 case showed a mutation in the DYS 458 locus due to the loss of one repeat unit and 3 cases showed one DYS 385I/II locus dropout. All mismatches were confirmed after the delivery. Seventeen fetuses’ haplotypes were not found in YHRD and one of them had a mutation, which corresponded to the paternity probability of 99.9812% and 95.7028%, respectively. Three fetuses’ haplotypes occurred twice in YHRD, which corresponded to paternity probability of 99.9437%. In conclusion, high discriminatory fetal Y-STR haplotype could be determined from maternal plasma during pregnancy starting at 12 weeks of gestation. All male fetuses could be attributed to the alleged father male lineage early in pregnancy. The high probability of paternity associated with each case suggests that the relationship is not random and this strategy can be use as an alternative for male fetal kinship analysis.     

The STR system hTPO: Population and segregation data

A population study was carried out on a random sample of 164 individuals from North Portugal using the short tandem repeat (STR) system hTPO (locus: 2p23-2pter). After electrophoresis, 7 alleles were identified of which 6 had been previously described and a new one, estimated to be 134 by long. The observed genotype distribution is in Hardy-Weinberg equilibrium. In order to assess the forensic applicability of the system, namely for paternity investigations, 109 mother-child pairs were analysed. No exclusions were found and the observed distribution did not deviate from the expected. Since hTPO has a relatively high information content (PIC = 0.60; H = 0.65) this system can be very useful in paternity investigations.     

Abstammungsbegutachtung mit der RFLP- und STR-Analyse

The combination of restriction fragment length polymorphism (RFLP) and short tandem repeat (STR) analyses for paternity analysis is presented. The two methods were compared by investigating 113 paternity cases. RFLP analysis was done using the single locus probes YNH24, MS31 and MS43A and for STR investigations the Identifiler Plus kit was employed. The lowest paternity probability obtained via RFLP analysis was 98.936% compared to 99.99844% when using STR analysis and the highest values were 99.9996 (RFLP) and >99.999999% (STR). Using 3 single locus DNA probes the paternity probability was <99.9% in 45.5% of the cases, while STR analysis always led to at least 99.9%. In 36 cases the father was excluded. Using STR analysis between 4 and 12 exclusions out of 15 investigated loci per case were observed. In 14 cases (39%) RFLP analysis alone did not yield the 3 exclusions necessary for exclusion of paternity. In summary it could be shown that in all cases both STR analysis alone and the combination of STR and RFLP investigations led to results which conformed to the requirements of the German guidelines.     

Evaluation of the paternity probability on an application of minisatellite variant repeat mapping using polymerase chain reaction (MVR-PCR) to paternity testing

Minisatellite variant repeat (MVR) mapping using polymerase chain reaction (PCR) was applied to a practical case of paternity testing to evaluate the paternity probability. In order to obtain single allele mapping by allele-specific MVR-PCR, three flanking polymorphic sites for each of the MS31A and MS32 loci were investigated and all three individuals were typed as heterozygous for at least one flanking polymorphic site at each locus. Allele-specific MVR-PCR was then performed using genomic DNA. It was confirmed that one allele in the child was identical to that from the mother and the other one in the child was identical to that from the alleged father. Mapped allele codes were also compared with those in the database by dot-matrix analysis, and no identical allele was found although some motifs were shared with Japanese alleles. The paternity index and the probability of paternity exclusion in the case at these two MVR loci were calculated using the presumed values of the allele frequencies. These studies seem to illustrate the practical value of MVR mapping of MS31A and MS32 loci in paternity testing.     

Short communication: imaging pulmonary embolism in pregnancy: what is the most appropriate imaging protocol?

Pulmonary embolism is the leading cause of death in pregnancy. Despite the difficulties in clinical diagnosis and the concerns regarding radiation of the fetus, the British Thoracic Society guidelines for imaging pulmonary embolism do not specifically address the issue of imaging for pulmonary embolism in this group. This communication discusses the difficulties of diagnosis and imaging pulmonary embolism in pregnancy and proposes a suitable imaging protocol. Clinical exclusion of patients from further imaging is recommended if the patient has a low pre-test probability of pulmonary embolism and a normal d-dimer. It is advised that all remaining patients undergo bilateral leg Doppler assessment. If this test is positive, the patient should be treated for pulmonary embolism; if negative, all patients should be referred for CT pulmonary angiography. Ideally, informed consent should be obtained prior to CT scanning. All neonates exposed to iodinated contrast in utero should have their thyroid function tested in the first week of life due to the theoretical risk of contrast induced hypothyroidism.     

Evaluation of incest cases of Turkey in terms of DNA profiling difficulties

We scanned suspicious 1200 paternity cases and 650 sexual abuse victims in Council of Forensic Medicine of Turkey between 2011 and 2014 and detected 50 incest cases and evaluated the forensic and genetic data of incest cases for source of DNA evidence, gender, age, SES (Socioeconomic status) and geographic location of victim, abusive person, extent of incest, pregnancy from incest and date of gestation termination and also aimed to discuss some DNA profiling difficulties.We detected incest from DNA evidences of curettage material (34%; Chorionic Villi (12%) and fetal tissue (22%)), alive baby after pregnancy (28%), sperm in vaginal swab (10%), sperm in anal swab (2%), sperm on clothing (24%) and in one case both sperm on clothing and in vaginal swab (2%). It was found that the most common incestuous relationship was elder-brother-sister incest (34%) and the second most common relationship was father-daughter incest (28%). The rarest incest was mother-son incest with only one reported case (2%). Forty-three victims (86%) were younger than 18 years old and 7 victims (14%) were older than 18 years old. Thirty-eight cases described full sexual intercourse and 31 of them culminated in pregnancy and 14 of them gave birth at the end of pregnancy.We had paternity rejection problem 3 (10%) of 31 incest cases between tested genetically related alleged fathers. Totally 20 STR loci did not discriminate the alleged fathers in two cases and we treated this problem increasing the number of STR loci and finally got the discrimination.In one case we detected same triallelic variant pattern at the same D3S1358 STR locus in both tested parents but child had not got STR variant; had only two alleles at this loci. We then evaluated the peak height values of STR variant alleles of tested persons and concluded a tetra-allelic baby without any STR incompatibility of 15 STR loci.Finally, forensic experts should aware of some DNA profiling difficulties while analyzing paternity incest cases due to increasing intra familial allelic share. We suggested that first try increasing the number of compared STR loci and secondly use alternative genetic markers and also be careful while evaluating triallelic STR variants.     

Improving accuracy and efficiency of mutual information for multi-modal retinal image registration using adaptive probability density estimation

Mutual information (MI) is a popular similarity measure for performing image registration between different modalities. MI makes a statistical comparison between two images by computing the entropy from the probability distribution of the data. Therefore, to obtain an accurate registration it is important to have an accurate estimation of the true underlying probability distribution. Within the statistics literature, many methods have been proposed for finding the ‘optimal’ probability density, with the aim of improving the estimation by means of optimal histogram bin size selection. This provokes the common question of how many bins should actually be used when constructing a histogram. There is no definitive answer to this. This question itself has received little attention in the MI literature, and yet this issue is critical to the effectiveness of the algorithm. The purpose of this paper is to highlight this fundamental element of the MI algorithm. We present a comprehensive study that introduces methods from statistics literature and incorporates these for image registration. We demonstrate this work for registration of multi-modal retinal images: colour fundus photographs and scanning laser ophthalmoscope images. The registration of these modalities offers significant enhancement to early glaucoma detection, however traditional registration techniques fail to perform sufficiently well. We find that adaptive probability density estimation heavily impacts on registration accuracy and runtime, improving over traditional binning techniques.     

Overestimation of pretest probability of coronary artery disease by Duke clinical score in patients undergoing coronary CT angiography in a Japanese population

BackgroundThe Duke clinical score (DCS) is commonly used to estimate the pretest probability of coronary artery disease (CAD). However, the criterion was developed in a population undergoing catheter angiography.ObjectiveTo test the hypothesis that DCS overestimates the CAD probability when applied to patients evaluated with coronary CT angiography (CCTA). A second objective is to compute an adjustment of the calculated DCS to apply to this population.MethodsThe DCS was calculated for the 3996 consecutive CCTA studies (February 2009 to April 2013) performed for symptomatic patients with no known CAD. Performance of the DCS for the detection of CAD was evaluated by the area under the receiver operating characteristic curve. Using the training cohort (n = 2789), a linear regression line between the calculated probability and the observed prevalence of CAD identified a modified DCS cutoff for a better risk categorization; this was internally validated by a separate cohort (n = 1207).ResultsThe DCS showed a good discrimination (area under the receiver operating characteristic curve = 0.71) for the detection of CAD (prevalence = 23.3%). The calibration analysis showed an overall 2.4-fold overestimation by DCS with a DCS < 23% corresponding to the low-risk category (ie, observed prevalence of CAD < 10%). There was no appropriate DCS cutoff to define high-risk category (ie, prevalence > 90%). The validation cohort showed a prevalence of 9.4% when DCS < 23% was used to define low risk.ConclusionAmong patients who underwent CCTA, DCS overestimated the pretest probability by at least 2-fold; the DCS < 23% should define the lower risk probability. The DCS poorly identifies high-risk population and thus development of new CCTA-based criteria is warranted.     

产前亲子鉴定方法研究(附23例报告)

目的对23个产前案例进行亲子鉴定。方法超声监视下行羊膜穿刺术,抽取羊水30~40ml。离心收集羊水沉渣后提取其基因组DNA,同时抽取其父母双方外周血基因组DNA。应用毛细管电泳技术和五色荧光复合扩增的方法,检测所有DNA样本的16个STR基因座基因型。结果所有羊水基因组DNA均来自独立个体,无母体DNA的污染。三联体分析显示23个案例中17例为肯定亲权关系,亲子关系概率均大于0.9999,6例确定为排除亲权关系,平均排除(位点数)指标为7.67个。二联体分析显示23个案例中17例肯定父权的平均亲子关系概率为0.9997以上,6例排除亲权关系的平均排除(位点数)指标为5个,但其中1例的排除位点只有1个。结论16个STR位点的多重荧光扩增方法在对羊水中母体DNA的污染程度进行评估的同时,可以准确、可靠的应用于产前亲子鉴定。在检测单亲鉴定案例时,若排除(位点数)指标小于2时必须补充母亲样本或增加检测的STR位点指标数,直至得出明确结论。     

Contrast media safety-an update

The value of contrast agents has for long been documented by their common daily use in imaging departments worldwide. In principle, they should be injected and leave the body immediately after use in the same condition or undergo natural metabolism without making any harm to the patient. However, this is not the case. It is of utmost importance to reduce the prevalence to as close as possible to zero. This can be done by identifying the patients at risk before administration of contrast agents. For acute non-renal adverse reactions, it is also important to be prepared for treating them instantly. The current review is a short state of the art regarding adverse reactions to contrast agents.     

Medical guidelines for space passengers--II

It now appears likely that commercial entities will carry paying passengers on suborbital spaceflights in this decade. The stresses of spaceflight, the effects of microgravity, and the limited capability for medical care onboard make it advisable to develop a system of medical clearance for such space tourists. The Aerospace Medical Association, therefore, organized a Space Passenger Task Force whose first report on medical guidelines was published in 2001. That report consisted of a list of conditions that would disqualify potential passengers for relatively long orbital flights. The Task Force reconvened in 2002 to focus on less stringent medical screening appropriate for short duration suborbital flights. It was assumed that such commercial flights would involve: 1) small spacecraft carrying 4-6 passengers; 2) a cabin maintained at sea-level "shirt-sleeve" condition; 3) maximum accelerations of 2.0-4.5 G; 4) about 30 min in microgravity. The Task Force addressed specific medical problems, including space motion sickness, pregnancy, and medical conditions involving the risk of sudden incapacitation. The Task Force concluded that a medical history should be taken from potential passengers with individualized follow-up that focuses on areas of concern.     

On the statistics of the “genetic fingerprint”

Summary In analogy to the polygene determined morphological features, the DNA-fingerprint is also not suitable for statistical processing. Statements about the individuality are merely speculative. Frequencies of genes cannot be found, since it is impossible to determine which combinations of bands belong to one gene locus. Hence the DNA fingerprint enables the recognition of exclusions from paternity; it does not, however, allow a statistical analysis, no matter which method be employed.