Use of X-linked short tandem repeat loci in routine parentage casework

BACKGROUND: Dealing with genetic inconsistencies in parentage testing, especially in motherless cases, remains a continual difficulty. STUDY DESIGN AND METHODS: Four difficult cases, comprising two trios and two duos, were selected from routine parentage testing casework. In these, relatively low combined paternity indices were observed as a result of few discrepant loci that were treated as being due to paternal mutations. An additional eight short tandem repeat (STR) loci along the X chromosome were studied in the alleged father and female child to try and help resolve these cases. RESULTS: In all four cases, the X chromosome haplotypes in the alleged father were different from those in the child, showing decisively that the alleged father could be excluded from being the biologic father of the child. CONCLUSION: In recent times the study of X chromosome haplotypes has been shown to be useful in parentage testing where the alleged father is absent and where only his close relatives are available for testing. This work demonstrates that such studies can also prove valuable in the testing of standard trios and duos in cases where there only a few genetic inconsistencies amongst the loci tested, making it difficult to distinguish between paternal mutations and a close relative of the alleged father being the biologic father.     

A method to calculate the plausibility of paternity using blood group results of any relatives (author's transl)]

A calculation program is described by means of which the frequency of any type of relationship in cases of disputable descent (questionable partenity, maternity, parenthood, brother- and sisterhood) using blood group results, can be calculated. Within the scope of forensical practice, the program is above all important in cases in which the alleged father and/or mother of the child is deceased, where however, blood group results of other relatives are at disposal, and also in cases of suspected incest - when the alleged father of the child is at the same time father or brother of the child's mother, and, finally, in cases where two men who are related to one another are considered as possible fathers. The program can also be applied to search cases.     

DNA analysis in a paternity case involving a triploid fetus

BACKGROUND: A parentage testing laboratory was asked to perform testing in a case of sexual assault that resulted in the conception of a child. Samples submitted to the laboratory included blood from the mother, the alleged father, and the fetus. CASE REPORT: DNA typing was used to determine if the suspect in this sexual assault was the father of the expected child. DNA extracted from these samples was subjected to both restriction fragment length polymorphism and polymerase chain reaction/short-tandem repeat analysis at a total of 13 genetic loci. Examination of DNA profiles for selected markers suggested that the fetus was triploid. Triploidy was confirmed through the use of fluorescent in situ hybridization of chromosomes, employing three chromosome-specific alpha satellite probes and fetal trophoblast nuclei. Statistical interpretation of the test results required identifying a method for calculation that would consider two transmitted paternal genes. Attempts to modify the standard method of calculating a paternity index were unsuccessful, because it was not possible to distinguish between dispermy and diandry as the mechanism of conception. Therefore, the likelihood ratio was calculated as the reciprocal of the random men not excluded value or the proportion of the population that possesses all of the paternal markers observed in the triploid fetus. CONCLUSION: Calculation of a likelihood ratio employing the exclusionary power of a collection of DNA markers appears to be the only method suitable for assigning weight to the significance of DNA matches between an alleged father and a child who is triploid.     

Limitations of paternity testing calculations

A total of 252 black and white trios (mother, child, and putative father) in which the alleged father was known not to be the biological father (BF) were generated from paternity studies. The likelihood of paternity (W) and the paternity index (P) were calculated on the basis of ABO, Rh, MNS, and HLA phenotyping. The results were then reviewed to evaluate the arbitrary limits proposed by a number of states in recent paternity legislation. Two hundred forty-four of 252 non-fathers (NFs) (96.8%) were excluded. Of the 152 white NFs, 147 (96.7%) were excluded; 97 of the 100 blacks (97%) were excluded. Eight NFs could not be excluded by the routinely performed tests. The W value for those eight trios ranged from 1.2 to 98.8 percent. Based on limits proposed in legislation, had the NFs actually been alleged fathers, as many as four of the eight of these men could have had the burden of proving that they were not the BFs.     

Blood groups and genetic markers polymorphism and probability of paternity

Recent advances in knowledge of blood groups' polymorphism provide aid to paternity diagnosis. When no exclusion is detected in any of the 20 or more systems available to the laboratory, validation of paternity is recommended. Two indices may be calculated: the proportion of males excluded by the phenotypes of the mother and child, and the probability of paternity of the alleged father. This latter index is based on bayesian process. The different formulations proposed by several authors are compared. The fact that a single exclusion in 20 or more systems needs to be denied or confirmed by indices of paternity is emphasized.     

Polymerase chain reaction and allele-specific oligonucleotides in paternity testing of the deceased

The assignment of paternity when the alleged father has died is now possible by use of a variety of allele-specific oligonucleotides after amplification of genomic DNA by the polymerase chain reaction (PCR). Issues relating to the inheritance of estates may be decided on fact rather than allegation. PCR-based genotyping of DQ alpha haplotypes from paraffin-embedded tissue of the deceased was used to prove non-paternity in the case reported here. Because the child was female, it was also possible to confirm the exclusion by using a second polymorphic site located in the factor VIII gene on the X chromosome.     

Full siblings impersonating parent/child prove most difficult to discredit with DNA profiling alone

DNA profiling is currently the most widely used method for parentage verification, although many forms of it have limitations of some sort. In this paper, a general formula is derived to depict a simple relationship between the probability that a random man and the probably that a male relative of the child, other than the child's father, is excluded from paternity, when the phenotype of the child's mother is unavailable. With this, the possible limitations of a finite set of STR loci in excluding close relatives of the child from paternity are illustrated. Genetically, among the commonly encountered biologic relationships, to exclude a full sibling of the child from paternity if they pose themselves as father and child remains the most difficult.     

Dead man talking: sustained utility of data from archaic paternity tests

BACKGROUND: Almost all relationship analysts now use molecular (DNA) tests to obtain necessary genetic information, yet older blood group tests remain valid. Circumstances may provide blood test results from old reports to avoid trying to sample DNA from inaccessible sources.
CASE STUDY: A mother recently claimed that a deceased man (alleged father [AF]) sired her child. Insurance investigation recovered two paternity test reports from an AABB-accredited laboratory. The 16- and 18-year-old reports employed blood groups and protein polymorphisms to exonerate two different men. One report contained the multilocus phenotypes of the AF and the other contained the phenotypes of the mother and child at the same loci. A new case was synthesized from the old reports.
RESULTS: Genetic inconsistencies (three direct and one indirect) were demonstrated among the nine loci that had been typed in both the AF and the mother-child pair.
CONCLUSION: New relationship tests may be reconstructed from phenotypes reported before the molecular test era. This approach avoids exhumation and other problematic methods of specimen retrieval.     

Analysis of paternity. The use of HLA and red cell antigens

Over a 6-year period, 866 cases were analyzed for disputed parentage. In 194 cases (22%), the alleged father was excluded as the biological father. One hundred and eight-one cases (93%) were direct exclusions, and 13 cases (7%) were indirect exclusions. Ninety-two percent of falsely accused men were identified by typing for HLA antigens alone. Exclusions based solely on red cell data occurred in 8 percent of the cases. When only HLA testing was performed, 177 of 362 (43%) cases had a probability of paternity of greater than or equal to 95 percent. When both HLA and red cell typings were performed, 110 of 160 (69%) cases had a probability of paternity of greater than or equal to 95 percent. No significant differences in the proportion of exclusions or proportion of alleged fathers with a probability of paternity of greater than or equal to 95 percent were observed between Caucasians or blacks. We conclude that typing for HLA antigens provides the most powerful data for excluding or including an alleged father. However, typing for red cell antigens adds significant data in excluding a falsely accused man and in determining the probability of paternity at a critical level (greater than or equal to 95%). In addition, the current study suggests that additional assays are needed to identify genetic characteristics of cases with probability of paternity less than 95 percent.     

Single-base substitutions give rise to a five-banded DNA profile at the D10S28 locus

Background : DNA profiles from variable number of tandem repeat (VNTR) loci typically are composed of two bands, one derived from each member of the homologous pair of chromosomes. DNA profiles composed of more than two bands result from mutations, and the uestion arises as to the mechanism underlying these unusual multibanded DNA profiles. Study Design and Methods : An alleged father in a paternity test was found to have a five-banded DNA profile at the D10S28 locus when his DNA was subjected to single-locus restriction fragment length polymorphism mapping with the restriction enzyme Pvu II. Results : Several results suggest that this complex DNA profile is the result of several single change within the VNTR locus First, there was no evidence of partial digestion of the DNA with Pvu II. Furthermore, the multibanded allele happened, in this case, to be transmitted to the child, who also showed a five-banded pattern composed of four bands inherited from the alleged father and one band inherited from the mother. Second, digestion of this DNA with Hae III resulted in the visualization of just two bands at the D10S28 locus. Conclusion : The results confirm the notion that mutations at VNTR loci are not always the result of additions or deletions of tandem repeats, but that they can also involve single-base substitutions either within or flanking VNTR loci that give rise to atypical DNA profiles and new alleles at the locus. single-base changes within or flanking VNTR loci that give rise to a typical DNA profiles and new alleles at the locus.     

A neonate with metabolic acidosis: Intentional ethylene glycol poisoning

We present a rare case of the intentional poisoning of a neonate. An 8-day old child presented to an academic pediatric emergency department (ED) with respiratory distress and decreased intake. In the ED the patient was stabilized, and workup uncovered an anion gap metabolic acidosis. Blood, urine, and CSF cultures were negative at 48 h and a metabolic screen revealed elevated glycine. Calcium oxalate crystals were later found in the urinalysis, raising concern for ethylene glycol poisoning. The patient's father admitted to mixing antifreeze with the child's formula. The workup of an ill or distressed neonate should be methodical, ruling out sepsis, inborn errors of metabolism, cardiac disease, trauma, and less common etiologies such as intestinal catastrophes, renal or hepatic disease, neurologic disease, drug withdrawal, non-accidental trauma, formula mixing errors, and poisoning.     

Empowering sibship analyses with reference pedigrees

BACKGROUND: In sibship analysis, the usual comparison of an alleged (test) sibling's short tandem repeat (STR) types with those of a reference sibling may prove inconclusive. Increasing the number of examined STR loci may not change sibship probabilities very much. We increased the number of verified reference siblings to resolve problematic cases of alleged sibship. STUDY DESIGN AND METHODS: (A) Ten paternity cases were chosen in which there were three highly probable children of each alleged father. Pairs of the alleged father's children were analyzed for full sibship. The test sib with the lowest likelihood of sibship was reanalyzed by a comparison with two reference siblings combined. (B) Five problematic sibship cases are presented to demonstrate how two‐person reference pedigrees can improve diagnosis over tests using one reference person. RESULTS: (A) Two‐person pedigrees exponentially increased sibship probabilities of true siblings above those produced by one reference person. (B) In problem cases, reference pedigrees provided data that: 1) statistically verified some alleged sibships in which analyses using one reference person yielded inconclusive results, 2) allowed exclusion of some alleged sibships, or 3) suggested alternate blood relationships to the alleged one. CONCLUSIONS: Use of reference pedigrees often resolves sibship questions left unsettled by tests using reference individuals. Adding reference relatives is a far more powerful analytical strategy than adding test loci. Whenever possible, verified blood relatives should be incorporated into a reference pedigree to retest an alleged sibling whose initial results were unclear.     

A national sample of US paternity tests: do demographics predict test outcomes?

BACKGROUND: Nearly 300,000 paternity tests are performed in the United States annually to include or exclude a male as the biological father of a child. Little is known about how well the test outcomes could be predicted simply on the basis of the subjects' social background. Our objective is to document the demographic composition of test subjects and to determine how well ethnic background and age predict paternity inclusion. STUDY DESIGN AND METHODS: A national database of 9999 paternity test results was formed weighted to represent the population of paternity establishment cases for the United States. Multiple regression determined the odds ratio of a paternity inclusion based on demographic variables such as race and age. RESULTS: The test results indicated paternity inclusions in 72 percent of cases, overall. The percent included varied little across racial and/or ethnic categories with a low of 67 percent in African Americans and a high of 82 percent among Native Americans, but these differences were not significant in multivariate analysis. The likelihood of inclusion showed a modest but significant correlation with increased maternal age. Mothers of European origin who nominated non-Europeans as fathers were less likely to identify the correct man as father. CONCLUSION: For any subject receiving a genetic test in a child support office, predicting a 72 percent probability that the test will show paternity inclusion offers as good an estimate of the test outcome as a subgroup estimate based on a subject's age, race, and child characteristics.     

亲子鉴定中二联体鉴定结果判定标准的探讨

目的探讨二联体亲子鉴定判定标准及结论描述并报道假定父亲与真实生物学父亲为同胞兄弟亲子鉴定1例。方法检测15个短串联重复序列基因座,包括13个CODIS基因座以及PentaE、PentaD。统计经三联体认定的二联体组合310例,分别采用上海司法部法庭司法科学技术研究所推荐的基因座频率、北京汉族基因频率和本实验室基因频率计算认定二联体的联合父权指数;统计69例排除案例的二联体组合不符合的基因座个数。结果 310例认定的二联体组合采用不同的基因座频率计算具有不同的联合父权指数,310例认定的二联体父权指数变化范围在101~1011之间,69例排除二联体组合不符合基因座的个数在2~13个之间。结论应用15个基因座进行亲子鉴定时,建议将二联体亲子鉴定结论的描述统一规范为排除或不排除,即检测发现三个或三个以上不符合基因座时,可以排除亲子关系;当15个短串联重复序列基因座都符合,且父权指数大于4000,不可以排除亲子关系;似然比小于4000时,建议补充另一方的样本或增加检测的基因座的个数。     

Experiences of the first year as father

BACKGROUND AND AIMS: The importance of fathers' participation for development of the child and the well-being of the family is recognized from earlier research. In Sweden, legislation allows fathers to share the parental leave equally with the mother even so fathers only use a small of their paid leave. The aim of the study was to explore experiences of the first year as a father. METHOD: A phenomenological life world approach was used. Ethical approval was obtained. Ten men, recruited by a purposive sample, were interviewed 12-14 months after the delivery of their first child. The data collection was performed during June and August 2004 in the south-west area of Sweden. FINDINGS: The essence of the experiences of the first year as father was to place the baby in the centre without giving up one's own person. The child provided warmth and happiness in the family and men experienced a deeper relationship to their partner. The contact between father and child was facilitated by engagement and time spent alone with the child. The major constituents identified from the findings were 'To be overwhelmed', 'To master the new situation' and 'To get a new completeness in life'. DISCUSSION AND CONCLUSION: To master fatherhood maintenance of integrity and possibility to develop an independent relationship with the child is important. Fathers are invited to participate in postnatal childbirth education but the activities address women's needs and it is doubtful if the fathers benefit from participation. Though fathers entered the delivery room some decades ago, as a support to the woman, health personnel of today must be aware of fathers' own needs and the impact gender aspects have on their professional support.     

Blood Group ABO Genotyping in Paternity Testing

Background

The ABO blood groups result from DNA sequence variations, predominantly single nucleotide and insertion/deletion polymorphisms (SNPs and indels), in the ABO gene encoding a glycosyltransferase. The ABO blood groups A₁, A₂, B and O predominantly result from the wild type allele A1 and the major gene variants that are characterized by four diallelic markers (261G>del, 802G>A, 803G>C, 1061C>del). Here, we were interested to evaluate the impact of ABO genotyping compared to ABO phenotyping in paternity testing.

Methods

The major ABO alleles were determined by PCR amplification with sequence-specific primers (PCR-SSP) in a representative sample of 1,335 blood donors. The genotypes were compared to the ABO blood groups registered in the blood donor files. Then, the ABO phenotypes and genotypes were determined in 95 paternity trio cases that have been investigated by 12 short tandem repeat (STR) markers before. We compared statistical parameters (PL, paternity likelihood; PE, power of exclusion) of both blood grouping approaches.

Results

The prevalence of the major ABO alleles and genotypes corresponded to the expected occurrence of ABO blood groups in a Caucasian population. The low resolution genotyping of 4 diallelic markers revealed a correct genotype-phenotype correlation in 1,331 of 1,335 samples (99.7%). In 60 paternity trios with confirmed paternity of the alleged father based on STR analysis both PL and PE of the ABO genotype was significantly higher than of the ABO phenotype. In 12 of 35 exclusion cases (34.3%) the ABO genotype also excluded the alleged father, whereas the ABO phenotype excluded the alleged father only in 7 cases (20%).

Conclusion

In paternity testing ABO genotyping is superior to ABO phenotyping with regard to PL and PE, however, ABO genotyping is not sufficient for valid paternity testing. Due to the much lower mutation rate compared to STR markers, blood group SNPs in addition to anonymous SNPs could be considered for future kinship analysis and genetic identity testing.     

Considerations for the interpretation of STR results in cases of questioned half-sibship

Likelihood ratios (LRs) were calculated for a cohort of 60 pairs of true half-sibs and compared with LR values calculated for unrelated, paired children. STR results for the half-sib group were obtained from 60 archived cases involving a true mother, two children, and an alleged father subjected to typing with a multiplex STR kit (Identifiler multiplex, Applied Biosystems) and in which the alleged father was excluded as the father of only one of the two children (half-sib pairs). The distribution of LR values among true half-sibs was compared to those produced from paired, unrelated children selected in two ways: One method for producing unrelated pairs was to randomly select Identifiler profiles from children in 120 distinct paternity cases and group them into 60 ethnically matched pairs (random pairs). In a second approach, the children in the true half-sib group were shuffled and ultimately paired with someone from a different case. A total of 49 ethnically matched, unrelated pairs were created (shuffled pairs). In the shuffled pairs group, comparisons were thus based on a constant set of phenotypes. LRs comparing the probability of half-sibship versus being unrelated were produced for all groups with standard methods. Among pairs of known half-sibs, LRs ranged from a low of 0.1 to a maximum of 3763. Among random and shuffled pairs, LRs ranged from a low of 0.0001 to 12 for shuffled pairs or 42 for random pairs. LRs of greater than 2 were produced in 8 instances among random pairs and in 4 instances among the shuffled pairs. Overall, results suggest that half-sib indices of 30 or greater are fairly characteristic of individuals who are related as half-sibs. In contrast, half-sib indices of 0.1 or less are fairly characteristic of unrelated individuals who claim to be half-sibs. LRs falling between 0.1 and 10.0 are uninformative, as this region represents the overlap in the LR distributions produced from the true and false half-sib groups when the Identifiler multiplex kit is used for testing.     

Fathering and the separation-individuation process

Empirical evidence supports the belief that fathers play a significant role in the development of children. The father is becoming a more visible participant in physical care (feeding, diapering, and bathing) and the emotional life of the infant. Father-infant interactions have resulted in early formation of attachment to the father, but later than with the mother. Separation anxiety is reduced if the father-infant interactions have been qualitatively satisfactory to the infant. Father-infant interactions have a definite effect on the infant's progression through the separation-individuation process as described by Mahler and Abelin. The father's behavior toward the infant, particularly during the practicing subphase, enhances ego autonomy, differentiation, and individuation. According to Abelin, completion of the separation-individuation process may be impossible for the mother and the child if the father does not interact with the child. In view of this deduction, the writer concludes that special effort should be made by child and health care workers to encourage fathers' involvement with their very young children. Also, further investigation is needed in order to identify specific father-infant interactions that might facilitate the separation-individuation process.     

Superfecundation identified by HLA, protein, and VNTR DNA polymorphisms

Summary. Parentage analysis has revealed a high probability that a man accused of paternity is the biological father of a male child. The child in this study, however, was the twin of a female child who could not have been fathered by the accused man. The mother of the children subsequently accused a second, unrelated man, who was excluded from paternity of the boy, but was very probably the biological father of the girl.