本文選題：法醫(yī)物證學(xué) + 親緣鑒定�。� 參考：《山西醫(yī)科大學(xué)》2011年碩士論文

【摘要】：目的:從其他親緣關(guān)系對常規(guī)親子鑒定干擾的角度,研究親緣鑒定的判定標(biāo)準(zhǔn),在需要檢驗基因座的總數(shù)量、排除概率與似然比率的校正等方面探討在考慮近親干擾時親子鑒定的評估策略。 方法:本課題研究內(nèi)容共分五部分。 1、調(diào)查一個家系,共四代25人。獲得常用15個基因座(CODIS+D2S1338,D19S433)的檢測分型結(jié)果,模擬叔侄關(guān)系替代父子關(guān)系構(gòu)成三聯(lián)體鑒定,統(tǒng)計易出現(xiàn)誤判(矛盾基因座數(shù)≤2)的案件比例。 2、選用親屬排除概率公式PER=(k_0+k_1)×PE與叔侄(祖孫、半同胞)關(guān)系的k系數(shù)校正單基因座排除概率;計算常用19個STR基因座(CODIS+D2S1338,D19S433,Penta D,Penta E,D12S391,D6S1043)的平均排除概率和累積排除概率,并與二項式分布定律公式聯(lián)合應(yīng)用,推算考慮近親干擾時親緣鑒定理論上至少應(yīng)檢測的STR基因座數(shù)量。 3、在北京地區(qū)人群中調(diào)查21個STR基因座(AGCU21+1系統(tǒng))的群體遺傳資料,并與常用19個STR基因座聯(lián)合應(yīng)用于常規(guī)親子鑒定中遭遇近親干擾的典型案例。 4、通過似然比率校正公式LR=k_0+(1-k_0)PI和典型父權(quán)指數(shù)(PI_(typical))推導(dǎo)在考慮其他親緣關(guān)系干擾時累積似然比率的快速估算法,并用此方法在2389例親子鑒定中評估考慮近親干擾時的風(fēng)險。 5、根據(jù)113個全同胞對和113個無關(guān)個體對的19個STR基因座分型結(jié)果,統(tǒng)計全同胞組和無關(guān)個體組的共有等位基因數(shù),使用SPSS軟件對兩組數(shù)據(jù)進(jìn)行判別分析。 結(jié)果:通過上述研究,主要得到以下結(jié)果。 1、本次研究中叔侄假冒父子關(guān)系參加親緣鑒定時的檢測結(jié)果表明:常規(guī)15個基因座時容易誤判的案件比例在三聯(lián)體鑒定中為17%;在二聯(lián)體鑒定中為37.5%。 2、考慮叔侄、祖孫、半同胞三種親緣關(guān)系干擾影響,校正后的單基因座PE值是校正前的0.75倍。為使累積似然比率達(dá)到1×10~4,在三聯(lián)體鑒定中,應(yīng)至少檢驗15個STR基因座(單基因座排除概率0.481);當(dāng)檢出1個矛盾基因座時,檢測基因座總數(shù)應(yīng)增加至24個;檢出2個矛盾基因座時,檢出總數(shù)應(yīng)增加至35個;檢出3個矛盾基因座時,檢出總數(shù)應(yīng)增加至43個。在二聯(lián)體鑒定中,應(yīng)至少檢驗21個STR基因座(單基因座排除概率0.358);當(dāng)檢出1個矛盾基因座時,檢測基因座總數(shù)應(yīng)增加至34個;檢出2個矛盾基因座時,檢出總數(shù)應(yīng)增加至48個。 3、本次群調(diào)新增20個非CODIS基因座(D19S433重復(fù))在北京地區(qū)人群中的遺傳資料,可與常用19個基因座聯(lián)合應(yīng)用。在遭遇近親干擾的親緣鑒定案例中,當(dāng)檢測基因座總數(shù)達(dá)到結(jié)果2中要求時,均避免了將矛盾基因誤判為遺傳變異。 4、在親緣鑒定中用累積似然比率(CPI)評估檢測結(jié)果時,如果考慮到近親干擾的可能,可以通過CPI×0.75~(n-m)快速估算校正后的累積似然比率(n為檢測基因座總數(shù),m為矛盾基因座個數(shù))。當(dāng)出現(xiàn)基因座符合遺傳規(guī)律但PI值1的情況時(母子表型相同時可能發(fā)生),該估算方法誤差較大。 5、在檢驗總數(shù)為19個STR基因座時,利用共有等位基因數(shù)(S)建立的判別函數(shù)與判別法則(L同胞=3.3408×S-39.8808;L無關(guān)=1.6685×S-10.4679;L(S)=max[L同胞(S)+ L無關(guān)(S)])可用于評估兩個體間是否為同胞關(guān)系,評估指標(biāo)為后驗概率。在S14和S21時,后驗概率達(dá)到99%以上,它們分別占到無關(guān)個體組的89.3%和全同胞組的83.2%;在S=16或17時可能出現(xiàn)判別錯誤,錯誤率約0.9%。 結(jié)論:在親緣鑒定中,當(dāng)孩子的某個非父近親代替孩子真正親代參與鑒定時,只檢測常用15個STR基因座將存在誤判風(fēng)險。當(dāng)檢測基因座總數(shù)達(dá)到本研究推導(dǎo)出的數(shù)量要求時,可以避免因近親干擾而造成錯誤。在評估STR檢測結(jié)果對父權(quán)假設(shè)的支持程度時,如果考慮近親干擾,可以通過本文提供的方法快速校正累積似然比率,使能夠大致把握檢測結(jié)果的證據(jù)強度。在涉及全同胞的鑒定中,可以通過共有等位基因數(shù)進(jìn)行輔助判別。本文推導(dǎo)的方法可以在一定程度上避免其他親緣關(guān)系對常規(guī)親子鑒定的干擾,為進(jìn)一步研究親子鑒定的標(biāo)準(zhǔn)提供了依據(jù)。
[Abstract]:Objective: To study the evaluation criteria of paternity identification from the angle of interference of other relatives to conventional paternity identification, and to study the evaluation criteria of paternity identification, and to discuss the evaluation strategy of paternity testing in consideration of the interference of close relatives in the aspects of the total number of loci, the correction of the probability of exclusion and the likelihood ratio.
Methods: the contents of this study were divided into five parts.
1, an investigation of a family, a total of four generations, 25 people, obtained the results of the detection and classification of common 15 CODIS+D2S1338 (D19S433), and simulated the relationship between nephew and nephew instead of father and son to form three body identification, and the proportion of cases of misjudgment (the number of contradictory loci less than 2) was easily found.
2, using the relative exclusion probability formula PER= (k_0+k_1) x PE and the relationship between the uncle and nephew (Zu Sun, half compatriots) to correct the exclusion probability of the single locus, and calculate the average exclusion probability and the cumulative exclusion probability of the 19 commonly used STR loci (CODIS+D2S1338, D19S433, Penta D, Penta E, D12S391), and combined with the binomial distribution law formula. The number of STR loci that should be detected in phylogenetic analysis should be considered when considering close relatives interference.
3, the population genetic data of 21 STR loci (AGCU21+1 system) were investigated in the Beijing population, and the typical cases of close relatives interference with the common 19 STR loci were used in the routine paternity test.
4, by using the likelihood ratio correction formula LR=k_0+ (1-k_0) PI and the typical paternity index (PI_ (typical)), the fast estimation method of cumulative likelihood ratio when considering the interference of other kinship relationships is derived, and the risk of close relatives interference is evaluated with this method in 2389 paternity tests.
5, according to the results of the 19 STR genotyping results from 113 full compatriots and 113 unrelated individuals, the total number of alleles in the whole compatriot group and the unrelated individual group was counted, and the data of the two groups were discriminate with the SPSS software.
Results: through the above research, the following results were obtained.
1, in this study, the test results of the relationship between the uncle and nephew of the uncle and nephew in the study showed that the proportion of the cases that were easily misjudged when the conventional 15 loci were misjudged was 17% in the three conjoint identification, and in the two conjoined identification was 37.5%.
2, considering the influence of nephew, grandson, grandson and half sibling, the PE value of the corrected monogenic pedestal is 0.75 times that before correction. In order to make the cumulative likelihood ratio reach 1 x 10~4, at least 15 STR loci should be tested at least 15 STR loci (single locus exclusion probability 0.481); when 1 contradictory loci are detected, the total number of detected loci should be increased. Add to 24; the total number of detectable 2 loci should be increased to 35; when 3 contradictory loci were detected, the total number should be increased to 43. At least 21 STR loci (Dan Jiyin exclusion probability 0.358) should be tested in two conjoined identification. When 1 contradictory base loci were detected, the total number of detected loci should be increased to 34; 2 detection should be detected. When the locus of the conflicting loci, the total number of detection should be increased to 48.
3, the genetic data in the population of 20 non CODIS loci (D19S433 repeats) in Beijing region can be combined with 19 common loci. In the case of consanguineous family identification with close relatives, when the total number of loci was detected in the result 2, the conflicting genes were misjudged to be genetic variation.
4, when using the cumulative likelihood ratio (CPI) to assess the test results, the cumulative likelihood rate after correction can be quickly estimated by CPI x 0.75~ (n-m) (n is the number of detected loci, M is the number of contradictory genes). It may occur at the same time, and the estimation method has a large error.
5, when the total number of 19 STR loci is tested, a discriminant function and a discriminant rule (L compatriot =3.3408 x S-39.8808; L independent =1.6685 x S-10.4679; L (S) =max[L compatriot (S) + unrelated) can be used to evaluate whether the two individuals are siblings, and the evaluation index is a posterior probability. Up to 99%, they accounted for 83.2% of the unrelated individuals and 83.2% of the full sib group, and there might be a discriminant error at S=16 or 17, with an error rate of about 0.9%..
Conclusion: in the paternity test, only 15 common STR loci will be found to be misjudged when a child's non parent relatives substitute for a child to participate in the identification. When the total number of loci reaches the number requirements derived from this study, the error caused by close relatives can be avoided. The paternity hypothesis of the STR test results is evaluated. In the support degree, if close relatives are considered, the cumulative likelihood ratio can be quickly corrected by the method provided in this paper, so that the evidence strength of the results can be roughly grasped. In the identification of all compatriots, the number of common alleles can be used to discriminate. The method derived in this paper can avoid others to a certain extent. The influence of genetic relationship on routine paternity testing provides a basis for further study of paternity testing criteria.
【學(xué)位授予單位】：山西醫(yī)科大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2011
【分類號】：D919

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