Seventy-seven cases of disputed parentage were studied using the human leucocyte antigen system over a 14-year period in Hong Kong. Of these, 30 (39.0%) related to the amendment or verification of birth registration details, 20 (26.0%) were for divorce or affiliation proceedings, and 19 (24.7%) were related to overseas resident visa applications. An exclusion of parentage of at least one of the alleged parents was shown in 23 (29.9%) cases; none of the cases related to overseas resident visa applications showed an exclusion. The study illustrates that human leucocyte antigen testing is a very powerful tool in the elucidation of disputed parentage in Hong Kong.published_or_final_versio

Hawkins, BR

Hong Kong Medical Journal

HKU Scholars Hub

Title Fourteen-year experience of human leucocyte antigen typing incases of disputed parentage in Hong KongAuthor(s) Hawkins, BRCitation Hong Kong Medical Journal, 1997, v. 3 n. 4, p. 369-372Issued Date 1997URL http://hdl.handle.net/10722/46965Rights Creative Commons: Attribution 3.0 Hong Kong LicenseHKMJ Vol 3 No 4 December 1997      369HLA typing in disputed parentageDepartment of Pathology, The University of Hong Kong, QueenMary Hospital, Pokfulam, Hong KongBR Hawkins, PhD, FRCPathCorrespondence to: Dr BR HawkinsIntroductionTyping for human leucocyte antigens (HLA) is a well-established method for the elucidation of disputed orunclear parentage.1-3 The technique is used extensivelyin some societies, but considerably less so in others.The types of cases in which the technique is used in-evitably differ from one culture to another, and willreflect the prevailing social need for the test. Only 77cases of disputed parentage have been tested usingHLA typing over a 14-year period in Hong Kong. Thispaper reviews those cases.Subjects and methodsStudy populationBetween 7 December 1982 and 31 December 1996,77 cases of disputed parentage involving 226 subjectswere tested at the Tissue Typing Laboratory of theDepartment of Pathology at The University of HongKong. The majority of the subjects tested were ethnicChinese, but also included were five Filipinos, oneIndian, one Thai, one Nepalese, and three Caucasians.Human leucocyte antigen typingHuman leucocyte antigen typing was performed byserological techniques using antisera that were standard-ised for use in a Chinese population. Most antisera wereFourteen-year experience of human leucocyte antigentyping in cases of disputed parentage in Hong KongBR HawkinsSeventy-seven cases of disputed parentage were studied using the human leucocyte antigen system over a14-year period in Hong Kong. Of these, 30 (39.0%) related to the amendment or verification of birthregistration details, 20 (26.0%) were for divorce or affiliation proceedings, and 19 (24.7%) were relatedto overseas resident visa applications. An exclusion of parentage of at least one of the alleged parents wasshown in 23 (29.9%) cases; none of the cases related to overseas resident visa applications showed anexclusion. The study illustrates that human leucocyte antigen testing is a very powerful tool in the eluci-dation of disputed parentage in Hong Kong.HKMJ 1997;3:369-72Key words: HLA Antigens; Paternity; Sensitivity and specificityobtained from sources in Hong Kong and were supple-mented where necessary by antisera and typing trayswhich were purchased from commercial suppliers. Thepanel of antisera covered a minimum of 17 specificitiesfor HLA-A, 34 for HLA-B, and 16 for HLA-DR. Tissuetyping that was performed prior to 1984 was restricted totesting for HLA-A and HLA-B specificities only. Tissuetyping that was performed subsequently included testingfor HLA-DR specificities, except in cases in which aclearly defined exclusion of parentage was shown byHLA-A and HLA-B typing alone.ResultsThe reasons for performing HLA typing in the 77 casesare shown in Table 1. The greatest proportion of referrals(39.0%) related to the amendment or verification of birthcertificate details and were performed at the request ofthe Hong Kong Immigration Department. Twelve of 30(40.0%) of these cases showed the exclusion of at leastone of the alleged parents. Of the 20 cases studied fordivorce or affiliation proceedings, five (25.0%) showedthe exclusion of at least one putative father. None of the19 applications for resident visas showed an exclusionof the claimed relationship. Eight others were tested forvarious reasons, including adoption or medical reasons.The number of parties tested in any particular case rangedfrom two to five. The configurations of the 77 cases andthe outcome of the tests are shown in Table 2.DiscussionThe use of inherited markers for the elucidation of dis-370      HKMJ Vol 3 No 4 December 1997Hawkinsputed or unclear parentage relies on two fundamentalprinciples: a genetic marker cannot appear in a childunless it is present in one or both of the child’s bio-logical parents; and, if an individual is homozygousfor a genetic marker, that marker must appear in anychild of whom that individual is a biological parent.As a corollary to the first of these principles, an addi-tional rule may be established that if an individual isheterozygous for a genetic marker, one of those mark-ers must appear in any child of whom the individual isa biological parent.The vast complexity of the HLA system4 makes itparticularly useful for the elucidation of disputed par-entage. There are many more alleles than for any othergenetic marker system, the inheritance patterns are wellestablished, and the antigens are well expressed on thetarget cells (lymphocytes) throughout life. The use ofDNA-based techniques has recently allowed the de-tection of an unprecedented array of subcomponentswithin the established HLA specificities. As a result,HLA typing now provides a level of success that farsurpasses the use of multiple combinations of othergenetic systems in the resolution of parentage disputes.5To ensure that a minor’s rights are adequately pro-tected and to discourage individuals “who just want tobe sure,” the Tissue Typing Laboratory at The Univer-sity of Hong Kong restricts HLA typing for parentageelucidation to three categories: when the test has beenordered by a court of law; at the request of a govern-ment immigration department, the Social Welfare orLegal Aid Departments of the Hong Kong Government;or at the request of a medical practitioner when thereTable 1. Reasons for performing human leucocyte antigen typingReason Exclusion Non-exclusion Total No. (%)Amendment of birth certificate details 12 15 27 (35.1)Verification of birth certificate details 0 3  3 (3.9)Late registration of birth 0 1  1 (1.3)Adoption 5 0  5 (6.5)Divorce or affiliation proceedings 5 15 20 (26.0)Application for US resident visa 0 18 18 (23.4)Application for Canadian resident visa 0 1  1 (1.3)Medical reasons 0 1  1 (1.3)Not specified 1 0  1 (1.3)Total 23 54  77Table 2. Number of subjects tested per case type and outcome of investigationSubjects tested Outcome TotalPF1* PF2† M‡ C1§ C2xx    Exclusion¶   Non-exclusion+ + + 6  30 36+ + + + 0 4 4+ + 3 11 14+ + + + 11 0 11+ + + + + 1 0 1+ + + 2 0 2+ + 0 1 1+ + 0 7 7+ + + 0 1 1Total 23 54 77*PF1   one putative father†PF2   second putative father‡M   alleged mother§C1   one alleged offspringxx C2   second alleged offspring¶One or more alleged parents excluded from parentage+HLA test performed for this individualHKMJ Vol 3 No 4 December 1997      371HLA typing in disputed parentageare justifiable medical grounds. Within the cases in-cluded in this survey, the greatest number of referralswere those from the Hong Kong Immigration Depart-ment and related to the verification of birth registra-tion details. These cases consisted of two main types:children whose fathers were originally named on thebirth certificates as the mother’s husband but who werelater claimed to be the offspring of a different father;and, children whose biological fathers were not avail-able when the child’s birth was registered and for whomanother person falsely claimed to be the father. This isof particular relevance in Hong Kong, because themother is normally listed on the birth registration cer-tificate under her unmarried surname and the father’sname has to be specified for the child to be knownunder the father’s surname.In one such case it was alleged that the paternalgrandfather of two children had been falsely named asthe father on the registration documents. Since an off-spring shares 50% of its genes with its biological fa-ther and 25% with its grandfather, there is only a 50%chance that a grandfather falsely accused of being thefather can be distinguished from the true father on thebasis of a single genetic system such as HLA. In thiscase the alleged grandfather was excluded from pater-nity of one child but not the other, whereas the allegedtrue father could not be excluded from paternity of ei-ther child. In at least two cases it was alleged that thefather’s brother had been falsely named on the regis-tration documents. In one such case the brother namedon the registration certificate was excluded from pa-ternity but the father was not. In another case the twobrothers in question had identical HLA phenotypes andcould not be distinguished. HLA typing of the allegedoffspring would not have been informative in this caseand was not performed.Approximately one quarter of the cases studiedwere at the request of overseas immigration authori-ties. Typically, these cases involved an alleged parentor offspring from overseas applying to the overseasimmigration authority to sponsor the respective allegedoffspring or parent for an overseas visa. HLA testingwas requested when, for example, birth registrationdocuments had been lost or destroyed, or for other rea-sons which attracted suspicion from the investigatingofficers. These cases often involved only one allegedparent and one alleged offspring, and the chances ofshowing an exclusion were correspondingly reduced.None showed an exclusion of the claimed relationship.Only one case was studied for medical reasons. Thiscase involved a child diagnosed as having β-thalas-saemia major but whose alleged father did not appearto carry the genetic defect present in the child. HLAtyping in this case could not exclude the alleged fatherfrom paternity of the patient.Many of the cases were referred to this laboratorywhen erythrocyte antigen grouping failed to show thealleged exclusion. It is known that the power of eryth-rocyte antigen grouping to reveal an exclusion of pa-ternity in a Chinese society is relatively low, comparedwith that in Caucasians.6 This study highlights thepower of the HLA system as a tool for the elucidationof disputed parentage. Of all the cases studied, 29.9%showed an exclusion of at least one of the alleged par-ents. Of the 15 cases in which two putative fathers weretested, 14 showed an exclusion of at least one of thetwo men by HLA typing. The one case that did notshow an exclusion involved two putative fathers whowere brothers who had identical HLA phenotypes.Identical phenotypes would be expected in 25% ofcases in which two brothers are named as possible fa-thers. The testing of such cases for additional geneticmarker systems could be beneficial because identityin one genetic system does not imply identity in an-other system.Because of the strict criteria imposed on the accept-ance of cases, the 77 cases reported in this paper willclearly not include all the cases of disputed paren-tageoccurring in Hong Kong during the study period. Ofthe cases which would meet the acceptance criteria, notall would have been referred for HLA typing. There isno shortage of medical laboratories offering erythrocyteantigen grouping facilities in Hong Kong and it is nowrelatively easy to obtain DNA testing in overseas labora-tories without the need for the subjects to leave HongKong. HLA typing still remains an option in manycases, however, and this study underlines the tremendouspower of the HLA system to help clarify what, for theparties involved, is often a highly stressful event in theirlives. The involvement of DNA-based technology inHLA typing is rapidly expanding and confers additionalsensitivity and specificity over serological methods7;we expect to see a greater proportion of cases referredfor medico-legal purposes in the future.References1. Jeannet M, Hässig A, Bernheim J. Use of the HL-A antigensystem in disputed paternity cases. Vox Sang 1972;23:197-200.2. Schacter BZ, Hsu SH, Bias WB. HLA and other genetic mark-ers in disputed paternity: a report of 50 cases. Transplant Proc1977;9(1 Suppl 1):233S-7S.372      HKMJ Vol 3 No 4 December 1997Hawkins3. Terasaki PI. Resolution by HLA testing of 1,000 paternity casesnot excluded by ABO testing. J Fam Law 1978;16:543-57.4. Hawkins BR. The HLA system and transplantation matchingin the 1990s. J Hong Kong Med Assoc 1993;45:77-86.5. Bodmer JG, Marsh SG, Albert ED, et al. Nomenclature forfactors of the HLA system, 1996. Hum Immunol 1997;53:98-128.6. Hawkins BR. The scope of blood genetic marker investiga-tions in paternity testing in Chinese and Malays. SingaporeMed J 1974;15:128-31.7. Bozón MV, Delgado JC, Turbay D, et al. Comparison of HLA-A antigen typing by serology with two polymerase chain reac-tion based DNA typing methods: implications for proficiencytesting. Tissue Antigens 1996;47:512-8.

Fourteen-year experience of human leucocyte antigen typing in cases of disputed parentage in Hong Kong

http://hub.hku.hk/bitstream/10722/46965/1/31288.pdf

Fourteen-year experience of human leucocyte antigen typing in cases of disputed parentage in Hong Kong

Abstract

Similar works

Full text

Available Versions

HKU Scholars Hub