Disomy of distal Xq in males: Case report and overview

Novelli, Antonio; Bernardini, Laura; Salpietro, D. C.; Briuglia, Silvana; Merlino, Maria; Mingarelli, Rita; Dallapiccola, Bruno

doi:10.1002/ajmg.a.30088

Cited by 24 publications

(17 citation statements)

References 11 publications

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“…12,13 Usually, they are inherited from heterozygous mothers in whom preferential inactivation of the dup(X) chromosome leads to a skewed X-inactivation pattern and results in a normal or mildly abnormal phenotype. 14 By contrast, structural X duplication in XY males results in functional disomy, and excess gene dosage leads to an abnormal phenotype.…”

Section: Discussionmentioning

confidence: 99%

Familial interstitial Xq27.3q28 duplication encompassing the FMR1 gene but not the MECP2 gene causes a new syndromic mental retardation condition

et al. 2009

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Section: Discussionmentioning

confidence: 99%

Familial interstitial Xq27.3q28 duplication encompassing the FMR1 gene but not the MECP2 gene causes a new syndromic mental retardation condition

et al. 2009

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“…In this report, we describe one case (case 4), in which the duplicated Xq28 chromosome material is translocated to the heterochromatic region of Yq, as seen in previously reported cases (Figure 2c). 15,20,21 Interestingly, our remaining three t(X;Y) cases (cases 1, 2, and 3) involve translocation of the duplicated X chromosome material to Yp rather than to Yq. Velinov et al 14 described an 8-year-old boy with a de novo duplication of approximately 2.15 Mb of Xq28, encompassing MECP2 but not L1CAM, and translocated to distal Yp.…”

Section: Discussionmentioning

confidence: 84%

“…19 A 2005 report by Sanlaville et al 2 reviews the aforementioned cases as well as two additional der(X)t(Xq;Yq) cases, including a de novo duplication of Xq28 translocated to Yq11.2 in a 13-month-old boy 20 and a de novo duplication of the region Xq27.3Àqter translocated to Yq11.2 in an 8-year-old boy. 21 In all of these cases, the mechanism was thought to be an aberrant pairing of the pseudoautosomal regions of Xq and Yq at male meiosis. In this report, we describe one case (case 4), in which the duplicated Xq28 chromosome material is translocated to the heterochromatic region of Yq, as seen in previously reported cases (Figure 2c).…”

Section: Discussionmentioning

confidence: 99%

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MECP2 duplications in six patients with complex sex chromosome rearrangements

et al. 2010

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Duplications of the Xq28 chromosome region resulting in functional disomy are associated with a distinct clinical phenotype characterized by infantile hypotonia, severe developmental delay, progressive neurological impairment, absent speech, and proneness to infections. Increased expression of the dosage-sensitive MECP2 gene is considered responsible for the severe neurological impairments observed in affected individuals. Although cytogenetically visible duplications of Xq28 are well documented in the published literature, recent advances using array comparative genomic hybridization (CGH) led to the detection of an increasing number of microduplications spanning MECP2. In rare cases, duplication results from intrachromosomal rearrangement between the X and Y chromosomes. We report six cases with sex chromosome rearrangements involving duplication of MECP2. Cases 1-4 are unbalanced rearrangements between X and Y, resulting in MECP2 duplication. The additional Xq material was translocated to Yp in three cases (cases 1-3), and to the heterochromatic region of Yq12 in one case (case 4). Cases 5 and 6 were identified by array CGH to have a loss in copy number at Xp and a gain in copy number at Xq28 involving the MECP2 gene. In both cases, fluorescent in situ hybridization (FISH) analysis revealed a recombinant X chromosome containing the duplicated material from Xq28 on Xp, resulting from a maternal pericentric inversion. These cases add to a growing number of MECP2 duplications that have been detected by array CGH, while demonstrating the value of confirmatory chromosome and FISH studies for the localization of the duplicated material and the identification of complex rearrangements.

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“…The prevalence of Xq duplications is still unknown, and only few have been reported. [6][7][8][9][10][11][12][13][14][15][16] To date, cryptic duplications encompassing MECP2 gene seem to be the most frequent microduplication syndrome responsible for cognitive impairment in patients with Xq distal duplications. Approximately 1% of unexplained XLMR may be caused by MECP2 duplications.…”

Section: Introductionmentioning

confidence: 99%

Xq26.2-q26.3 microduplication in two brothers with intellectual disabilities: clinical and molecular characterization

et al. 2010

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Partial duplications involving the long arm of the X chromosome are associated with mental retardation, short stature, microcephaly, hypopituitarism and a wide range of physical findings. We identified an inherited Xq26.2-Xq26.3 duplication in two brothers with severe mental retardation, hypotonia, growth delay, craniofacial disproportion and dental malocclusion. Chromosome analysis was normal and multiplex ligation-dependent probe amplification analysis detected duplication on Xq26. Further characterization by array comparative genomic hybridization and quantitative PCR helped to determine proximal and distal duplication breakpoints giving a size of approximately 2.8 Mb. The duplication encompasses 24 known genes, including the X-linked mental retardation genes ARHGEF6, PHF6, HPRT1 and SLC9A6. Clinical and molecular characterization of Xq duplications will shed more light into the phenotypic implication of functional disomy of X-chromosome genes.

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Disomy of distal Xq in males: Case report and overview

Cited by 24 publications

References 11 publications

Familial interstitial Xq27.3q28 duplication encompassing the FMR1 gene but not the MECP2 gene causes a new syndromic mental retardation condition

Familial interstitial Xq27.3q28 duplication encompassing the FMR1 gene but not the MECP2 gene causes a new syndromic mental retardation condition

MECP2 duplications in six patients with complex sex chromosome rearrangements

Xq26.2-q26.3 microduplication in two brothers with intellectual disabilities: clinical and molecular characterization

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