A Dual Gender Rare Case with 47,XY, + 18/46,XX Karyotype: Chimera or Mosaic?

Nurul Alia Nawi,Foong Eva,Aziati Annuar,Cheng Yi Ting,Zulaikha Abu Bakar,Nazihah Mohd Yunus,Ravindran Ankathil,Sarina Sulong

doi:10.1055/s-0040-1722275

Abstract

Our objective is to report one rare case of dual gender chimerism involving abnormal male trisomy 18 and normal female karyotype. The baby was born full term with birth weight of 1.8 kg, not vigorous with light meconium stained liquor and Apgar score of 51, 85 and 910. Parents are 40 years old and mother is G6P5 + 1. The baby had clinical features of Edwards syndrome, and a blood sample was sent to Human Genome Centre, Universiti Sains Malaysia, Malaysia for cytogenetic analysis. Conventional cytogenetic analysis results showed two distinct sex discordant genetic cell lines XY and XX in 90:10 ratio. The male genetic cell line XY also showed trisomy 18 (47,XY, + 18) consistent with clinical diagnosis of male Edwards syndrome, whereas the second genetic cell line showed normal 46,XX female. The present case was reported as dual gender chimera with chi 47,XY, + 18/46,XX karyotype pattern. To the best of available knowledge, dual gender chimerism with abnormal male trisomy 18 and normal female karyotype has not been reported so far, and this case is reported for its rarity and as the first report.

Highlights

Individuals who have two or more distinct populations of cells in the body can either be labeled as a mosaic or chimera depending on the mechanism of formation of these different cell lines
Our objective is to report one rare case of dual gender chimerism involving abnormal male trisomy 18 and normal female karyotype
To the best of available knowledge, dual gender chimerism with abnormal male trisomy 18 and normal female karyotype has not been reported so far, and this case is reported for its rarity and as the first report

Summary

Introduction

Individuals who have two or more distinct populations of cells in the body can either be labeled as a mosaic or chimera depending on the mechanism of formation of these different cell lines. It is expected that many chimeras are healthy and are almost never detected, especially if both zygotes are of the same genetic sex unless they exhibit abnormalities such as mismatched eyes color, partlycolored hair, uneven skin pigmentation, or hermaphroditic genitalia. Dual gender chimeras (46,XX/46,XY cell lines) account for 13% of true hermaphrodites and are diagnosed at birth due to ambiguous external genitalia.[2] Rarely dual gender chimerism has been reported in cases in which a normal cell lineage (disomy) coexists with an abnormal (trisomy) one, each causing a distinct sex chromosome complement. We report an extremely rare case of dual gender trisomy/disomy chimerism with abnormal male trisomy 18 and normal female karyotype

Objectives

Findings

Conclusion