American Journal of Medical Genetics 42856 (1992)
Letter to the Editor Genetic Analyses on a Set of Parasitic Conjoined Twins To the Editor:
allelic fragments a t the apolipoprotein B 3‘ hypervariable locus. This has a minimum of 12 alleles making it a highly informative marker locus [Boerwinkle et al., In the United States parasitic conjoined twins occur in 19891. about one or two per million births [Husain et al., 19891 In conclusion, our analyses indicate that our set of and i t is assumed, for the literature contains little exper- parasitic conjoined twins is monozygotic, chromosomimental proof, that they are monozygotic. However, di- ally identical, and otherwise genetically identical zygotic chimerism due to zygotic or later preimplanta- within the discriminatory power of the technology emtion embryonic fusion might also be a mechanism. Even ployed. if such a twin set were indeed monozygotic, the two REFERENCES members still need not be chromosomally or otherwise genetically identical [Thompson et al., 19911. We were Boerwinkle E, Xiong W, Fourest E, Chan L (1989):Rapid typing of presented recently with the opportunity to test these tandemly repeated hypervariable loci by the polymerase chain reaction:Application to the apolipoprotein B 3’ hypervariableregion. alternatives with the birth of a set of parasitic conjoined R o c Natl Acad Sci USA 86:212-216. white male twins to a 28-year-old gravida 3, para 2, AN, MuraskasJ, Lambert G, Dado D, Lynch J (1989):Parasitic woman after a term, uneventful pregnancy. The para- Husain conjoined twins with omphalocele and tetrology of Fallot. Pediat site, consisting of a headless male twin without axial Pathol 9:321-328. skeleton or patent anus, was joined at the top of its Saiki RK, Gelfand DH, Stoffel S, Scharf SJ, Higuschi R, Horn KB, thorax to the host twin at the latter’s lower chest and Mullis KB, Erlich HA (1988):Primer-directed enzymaticamplification of DNA with a thermostable DNA polymerase. Science upper abdomen. The twins were successfully separated 239:487-489. surgically a t 3 days of life and the host twin is doing well Thompson MW, McInnes RR, Willard HF (1991): Thompson & a t home 5 months later. Thompson-“Genetics in Medicine,” 5th ed. Philadelphia: W. B. At surgery skin samples were obtained from the host Saunders, pp 242, 389-391. twin and parasite and from their junction site and scru- Vassart G, Georges M, Monsieur R, Brocas H, Lequarre AS,Christophe D (1987): A sequence in M13 phage detects hypervariable minipulously separated fibroblast cultures established. satellites in human and animal DNA. Science 235683-684. G-banded karyotypes on the three cultures were normal male and appeared identical to each other and to the Mark W. Steele G-banded karyotype on a peripheral blood sample from the host twin. DNA fingerprints of the 3 fibroblast culSharon L. Wenger Departments of Pediatrics tures were identical using the M13 bacteriophage probe Ranjan Deka [Vassart et al., 19871. The M13 bacteriophage probe is John J. Mulvihill immensely useful since it detects multiple loci simulDepartment of Human Genetics taneously and provides a n individual specific Kanthorn Sukarachana fingerprint. With this probe identity has been shown Department of Surgery only in monozygotic twins [Vassart et al., 19871. DNA from the 3 fibroblast cultures, after appropriate PCR University of Pittsburgh Health Center Pittsburgh, Pennsylvania amplification [Saiki et al., 19881, also showed identical
Received for publication September 30, 1991. Address reprint requests to Mark W. Steele, M.D., Division of Medical Genetics, Children’s Hospital of Pittsburgh, 3705 Fifth Avenue at DeSoto Street, Pittsburgh, PA 15213.
0 1992 Wiley-Liss, Inc.
Letter to the Editor Genetic Analyses on a Set of Parasitic Conjoined Twins To the Editor:
allelic fragments a t the apolipoprotein B 3‘ hypervariable locus. This has a minimum of 12 alleles making it a highly informative marker locus [Boerwinkle et al., In the United States parasitic conjoined twins occur in 19891. about one or two per million births [Husain et al., 19891 In conclusion, our analyses indicate that our set of and i t is assumed, for the literature contains little exper- parasitic conjoined twins is monozygotic, chromosomimental proof, that they are monozygotic. However, di- ally identical, and otherwise genetically identical zygotic chimerism due to zygotic or later preimplanta- within the discriminatory power of the technology emtion embryonic fusion might also be a mechanism. Even ployed. if such a twin set were indeed monozygotic, the two REFERENCES members still need not be chromosomally or otherwise genetically identical [Thompson et al., 19911. We were Boerwinkle E, Xiong W, Fourest E, Chan L (1989):Rapid typing of presented recently with the opportunity to test these tandemly repeated hypervariable loci by the polymerase chain reaction:Application to the apolipoprotein B 3’ hypervariableregion. alternatives with the birth of a set of parasitic conjoined R o c Natl Acad Sci USA 86:212-216. white male twins to a 28-year-old gravida 3, para 2, AN, MuraskasJ, Lambert G, Dado D, Lynch J (1989):Parasitic woman after a term, uneventful pregnancy. The para- Husain conjoined twins with omphalocele and tetrology of Fallot. Pediat site, consisting of a headless male twin without axial Pathol 9:321-328. skeleton or patent anus, was joined at the top of its Saiki RK, Gelfand DH, Stoffel S, Scharf SJ, Higuschi R, Horn KB, thorax to the host twin at the latter’s lower chest and Mullis KB, Erlich HA (1988):Primer-directed enzymaticamplification of DNA with a thermostable DNA polymerase. Science upper abdomen. The twins were successfully separated 239:487-489. surgically a t 3 days of life and the host twin is doing well Thompson MW, McInnes RR, Willard HF (1991): Thompson & a t home 5 months later. Thompson-“Genetics in Medicine,” 5th ed. Philadelphia: W. B. At surgery skin samples were obtained from the host Saunders, pp 242, 389-391. twin and parasite and from their junction site and scru- Vassart G, Georges M, Monsieur R, Brocas H, Lequarre AS,Christophe D (1987): A sequence in M13 phage detects hypervariable minipulously separated fibroblast cultures established. satellites in human and animal DNA. Science 235683-684. G-banded karyotypes on the three cultures were normal male and appeared identical to each other and to the Mark W. Steele G-banded karyotype on a peripheral blood sample from the host twin. DNA fingerprints of the 3 fibroblast culSharon L. Wenger Departments of Pediatrics tures were identical using the M13 bacteriophage probe Ranjan Deka [Vassart et al., 19871. The M13 bacteriophage probe is John J. Mulvihill immensely useful since it detects multiple loci simulDepartment of Human Genetics taneously and provides a n individual specific Kanthorn Sukarachana fingerprint. With this probe identity has been shown Department of Surgery only in monozygotic twins [Vassart et al., 19871. DNA from the 3 fibroblast cultures, after appropriate PCR University of Pittsburgh Health Center Pittsburgh, Pennsylvania amplification [Saiki et al., 19881, also showed identical
Received for publication September 30, 1991. Address reprint requests to Mark W. Steele, M.D., Division of Medical Genetics, Children’s Hospital of Pittsburgh, 3705 Fifth Avenue at DeSoto Street, Pittsburgh, PA 15213.
0 1992 Wiley-Liss, Inc.
