X chromosome-specific Array-CGH of XLMR patient

Mental retardation (MR) is a non-progressive cognitive impairment affecting 2 to 3% of the Western population. So far, point mutations and subtle deletions and insertions have been shown to represent only a proportion (<40%) of genetic causes underlying X-linked mental retardation (XLMR). We have screened a subset of 300 presumable X-linked families by X chromosome-specific array-CGH and identified 6 families with overlapping microduplications at Xp11.22 containing two candidate genes; both of which showed overexpression in the affected individuals. Array-CGH data revealed aberrant Cy5/Cy3 log2 ratios for different but overlapping sets of clones indicating varying sizes of these duplications in the different families. Keywords: comparative genomic hybridization X chromosome-specific array-CGH performed for probands of families A, FAM3, B, MRX17, C, MRX31, and D, A057, revealing the duplications at Xp11.22. DNA from two unrelated MR patients were differentially labeled and co-hybridized onto the X-array. The patients with duplications were hybridized in Cy5 against unrelated MR patients, named Pat XY1-6, in the Cy3 channel.