Turner syndrome mosaicism: an unusual case with a de novo large dicentric marker chromosome: mos 45,X/46,X, ter rea(X;X)(p22.3;p22.3)

Abstract

X/X translocations are quite rare in humans. The effect of this anomaly on the phenotype is variable and depends on the amount of deleted material and whether the chromosomes are joined by their long or short arms. We report an unusual case of Turner syndrome mosaicism in a 16-year-old girl, who was referred to our Institute for primary amenorrhoea associated with short stature. Endocrine evaluation revealed hypergonadotropic hypogonadism, which required a study of the karyotype. Cytogenetic analysis, performed on peripheral blood leucocytes, showed a mos 45,X/46,X,ter rea (X;X)(p22.3;p22.3) de novo karyotype. The prevalent cell line was 45,X (90% cells). A second cell line (10% cells) showed a very large marker chromosome, similar to a large metacentric chromosome. FISH (fluorescent in situ hybridisation) and molecular analysis revealed that the marker chromosome was dicentric and totally derived from the paternal X chromosome.

Cytogenetic studies of 1232 patients with different sexual development abnormalities from the Sultanate of Oman

“…In the present study's patients, 45,X was the most prevalent aberration observed (46.4%), followed by diverse mosaicism (38%), while pure structural anomalies accounted for only 13.4% of cases. Similarly, previous studies from Serbia, Italy, Indonesia and Kuwait revealed 45,X as a more prevalent karyotype with frequencies of 48.4% (Djordjević et al, 2010), 50% (Nucaro et al, 2008), 41.1% (Marzuki et al, 2011) and 63% (Abulhasan et al, 1999), respectively. Approximately 95-99% of 45,X embryos fail to survive to term, although they demonstrate mild phenotypic abnormalities compared with autosomal aneuploidy (Hook and Warburton, 1983).…”