A rare case report of 46XY mixed gonadal dysgenesis
An ovotesticular disorder of sex development (OT-DSD) was rarely found in human. The mechanism causing such condition is poorly understood. We hereby reported a 11-year-old child with OT-DSD and a karyotype 46,XX/46,XY, a single maternal and double paternal genetic contribution to the patient. Fluorescence in situ hybridization (FISH), blood grouping, HLA (human leukocyte antigen) haplotyping and a genome-wide scanning of lymphocytes with 398 short tandem repeat microsatellite markers were performed to investigate the origin of the cell lines concerned. ABO typing revealed that two populations of red cells were in the patient, which were group A and group B, both from paternal alleles. HLA haplotyping showed the patient had three haplotypes. Haplotype 1 was inherited from maternity, haplotype 2 and 3 were from paternity. The STR microsatellite analysis showed 25 of the 74 fully informative markers in both parents, three alleles were inherited: one of them was from mother, another two were from father. Seventeen of the thirty-eight paternal markers, the patient inherited two paternal alleles. For 121 informative maternal markers, the patient had a single maternal allele. There were two distinct alleles in locus DXS6810 and DXS1073 on X-chromosome, in which one was from the mother and the other from the father. The patient was a single maternal and double paternal genetic, which was a type of a parthenogenetic division of a maternal haploid nucleus into two identical nuclei, followed by fertilization by two spermatozoa and fusion of the two zygotes into a single individual at the early embryonic stage. To the best of our knowledge, this is the oldest OT-DSD case of parthenogenetic chimerism. These data provide additional evidence that a parthenogenetic maternal and double paternal contribution causes 46,XX/46,XY OT-DSD.