A Girl with 10 Mb Distal Xp Deletion Arising from Maternal Pericentric Inversion: Clinical Data and Molecular Characterization

Abstract

Background: Short arm deletions of the X-chromosome are challenging issues for genetic counseling due to their low penetrance in population. Female carriers of these deletions have milder phenotype than male ones, considering the intellectual ability and social skills, probably because of the X-chromosome inactivation phenomenon.

Case report: A female patient with a 10Mb distal Xp deletion and an Xq duplication, showing mild intellectual disability, is described in this report. While the deletion arose from a maternal pericentric inversion, the duplication was directly transmitted from the mother who is phenotypically normal.

Conclusion: This report underlines the usefulness of molecular cytogenetic technics in postnatal diagnosis.

Keywords: Array CGH; Classical cytogenetics; Genetic counseling; Pericentric inversion; Xp deletion; Xq duplication.

Fig. (1)

The possible mechanism of the rec(X) chromosome generation. The normal chromosome and the inverted one with breakpoints at p22.1q28 are shown at the left. A recombination between the normal and the invert chromosome had as a result the rec(X). The recombination should have happened in a region between the breakpoints of the inverted chromosome. The green line shows the maternal duplication which was inherited to the current patient.

Fig. (2)

aCGH of the current patient (above). On the left side and in the middle is the deletion, while the duplication is on the right side. At the bottom are the genes deleted at the current patient.

Fig. (3)

FISH analysis of the current patient’s and her mother’s X chromosome. (A) and (B) The normal and the derivative X chromosome of the mother are shown. The derivative chromosome is inverted and has a qter duplication. (C) and (D) The normal and the derivative X chromosome of the current patient are shown. The derivative chromosome has a qter duplication and a pter deletion.