Analysis of Phenotype and Karyotype of Children Born From Mothers With 45,X/46,XX Mosaicism

In the light of the contemporary definition of Turner syndrome (TS), not all cases of 45,X/46,XX mosaicism should be considered as this syndrome. This report describes 2 mothers with 45,X/46,XX karyotype and their offspring. In one family, a mother and 2 daughters had 45,X/46,XX mosaicism. In the second one, a mother with a mosaic karyotype delivered 2 children, 1 healthy and 1 with Xp deletion, 46,Xdel(X)(p11.2). In both families, the daughters were initially diagnosed as TS, whereas mosaicism in their mothers was confirmed during further analysis. All 3 daughters with chromosomal aberrations had somatic and/or visceral TS stigmata, menstrual cycle disturbances and 2 of them were short in stature. However, the clinical presentation differs substantially between the mothers and their offspring as well as between siblings of the same mother. We also observed that a similar karyotype may result in a dissimilar phenotype, even in 1 family. This report shows that determining the diagnosis of TS might be a complicated task, especially in patients with low 45,X/46,XX mosaicism. It also indicates that there is a need for genetic counseling for mothers of daughters with TS.