A case of 46,XX/46,XX chimerism in a phenotypically normal woman
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CASE REPORT
A case of 46,XX/46,XX chimerism in a phenotypically normal woman Sohee Cho 1 & Hwan Young Lee 1,2 & Moon-Young Kim 1 & Sung-Hee Lyoo 1 & Soong Deok Lee 1,2 Received: 18 December 2019 / Accepted: 3 April 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Chimerism is the presence of two genetically different cell lines within a single organism, which is rarely observed in humans. Usually, chimerism in the human body is revealed by the finding of an abnormal phenotype during a medical examination or is unexpectedly detected in routine genetic analysis. However, the incidence or underlying mechanism of chimerism remains unclear due to the lack of information on this infrequent biological event. A phenotypically normal woman with a 46,XX karyotype and atypical short tandem repeat (STR) allelic patterns observed in DNA analysis was investigated with various genetic testing methods, including STR typing based on capillary electrophoresis and massively parallel sequencing, genomewide SNP array, and a differentially methylated parental allele assay (DMPA). The proband’s parents were not available for testing to discriminate the parental allelic contribution, but the parents’ alleles were recovered from testing the proband’s siblings. Based on the results consistently found in multiple analyses using STR and single nucleotide polymorphism (SNP) polymorphism markers, dispermic fertilization was suggested as the underlying mechanism. The application of various molecular genetic testing methods was used to elucidate the chimerism observed in the proband in this study. In the future, the development of novel genetic markers or techniques, such as DMPA, may have potential use in the investigation of chimerism. Keywords Chimerism . Karyotyping . STR typing . Genome-wide SNP array . Differentially methylated parental allele assay
Introduction The typing of polymorphic short tandem repeat (STR) loci has been widely used in forensic DNA analysis and paternity testing since multiple allelic variants of STR markers at a single locus can provide high discrimination power [1]. Usually, autosomal STRs (A-STRs) are genotyped as a monoallelic pattern (a homozygous genotype) or a diallelic pattern (a heterozygous genotype) in an individual, in which two alleles are inherited from either one’s father or one’s mother. Atypical allelic patterns with three or four alleles are rare [2, 3] but can be unexpectedly observed in routine DNA profiling Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00414-020-02296-y) contains supplementary material, which is available to authorized users. * Soong Deok Lee [email protected] 1
Institute of Forensic and Anthropological Science, Seoul National University College of Medicine, Seoul, South Korea
2
Department of Forensic Medicine, Seoul National University College of Medicine, 103 Daehak-ro, Jongno-Gu, Seoul 03080, South Korea
[2–5]. A tri-allelic pattern at a single locus within an individual is one of the most frequent
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