X-X translocations

Epidemiology and Etiology:

· 46,X,der(X),t(Xp?;Xq?)

· Dup/del of Xp/Xq or vice versa

· Some may be isodicentric

· Possible mechanisms:

· Unequal recombination between two X chromosomes in the oocyte

· One X chromosome folding in on itself (more likely paternal)

· U-type exchange

Common sites:

· Xp11.23

· Xq21.3

Gross features:

· SHOX gene haploinsufficiency (Xp terminal):

· Short stature

Histologic features:

·

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

·

Other features:

· Pubertal and/or menstrual abnormality usually

· Infertility

· Maternal transmission has been recorded however

References:

· Gardner RJM, Sutherland GR. Chromosome Abnormalities and Genetic Counseling. 2nd ed. Oxford University Press, USA; 1996.