Figure 1.

Schematic representation of a Xq duplication transmission. Active X and Y chromosomes are in grey, inactive X is striped in black. A yellow star represents XIC. a) normal XY chromosomes; b) Xq duplication in male leading to Xq functional disomy, associated with an abnormal phenotype; c) Xq duplication in female with inactivation pattern skewed towards the duplicated X, associated with a normal phenotype; d) Xq duplication in female with inactivation pattern skewed towards the normal X leading to Xq functional disomy, associated with an abnormal phenotype.