A familial Xp+ chromosome, dup (Xq26.3--&gt;qter).

Vásquez, Ana Isabel; Rivera, Horacio; Bobadilla, L; Crolla, John A.

doi:10.1136/jmg.32.11.891

Cited by 32 publications

(42 citation statements)

References 18 publications

(1 reference statement)

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“…An alternative explanation would be that the PMD duplication mutations might belong to the category of cytogenetically unbalanced X chromosomes which are preferentially inactive, regardless of the map position of the unbalanced segment. [34][35][36][37][38] In contrast to the duplication mutation the PMD deletion mutation in patient PMD25 did not result in a skewed X inactivation pattern. The most likely explanation would be that this deletion of about 100 Kb does not affect cell growth, as has been described in other deletions, such as those involving the FMRI and DMD genes, 39,40 and unlike the 800 kb deletion in Xq28.…”

Section: Discussionmentioning

confidence: 99%

X inactivation phenotype in carriers of Pelizaeus-Merzbacher disease: skewed in carriers of a duplication and random in carriers of point mutations

Woodward¹,

Kirtland²,

Dlouhy

et al. 2000

Eur J Hum Genet

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Pelizaeus-Merzbacher disease (PMD)is an X-linked recessive disease caused by coding sequence mutations in the PLP gene, sub-microscopic duplications of variable sizes including the PLP gene or very rarely deletions of the PLP gene. We analysed the X inactivation pattern in blood of PMD female carriers with duplications and with point mutations. In the majority of duplication carriers (7/11), the X chromosome bearing the duplication was preferentially inactivated, whereas a random pattern of X inactivation was detected in point mutation carriers (3/3), a deletion carrier (1/1), affected females (4/4) who did not have a recognised mutation and normal control females. However 2/5 non-carrier female relatives of patients with a duplication, had skewed X inactivation. The skewed pattern of inactivation observed in most duplication carriers and not in mutation carriers suggests a) that there is selection against those cells in which the duplicated X chromosome is active and b) other expressed sequences within the duplicated region rather than mutant PLP may be responsible. Since the skewed X inactivation did not segregate with the disease in two families and the pattern of X inactivation was variable among the duplication carriers, the pattern X inactivation is an unsuitable diagnostic tool for female carriers of PMD European Journal of Human Genetics (2000) 8, 449-454.

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Section: Discussionmentioning

confidence: 99%

X inactivation phenotype in carriers of Pelizaeus-Merzbacher disease: skewed in carriers of a duplication and random in carriers of point mutations

Woodward¹,

Kirtland²,

Dlouhy

et al. 2000

Eur J Hum Genet

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“…These cases are presumed to be the result of either a recombination event in a parent carrying a pericentric inversion [23][24][25][26][27] or inherited from a phenotypically normal mother carrying the abnormal X. 28 We report two additional cases in which an Xq duplication encompassing MECP2 was accompanied by an Xp deletion, resulting from a specific intrachromosomal rearrangement in which the duplicated segment of Xq was translocated to the Xp22.3 band.…”

Section: Xp-xq Rearrangementsmentioning

confidence: 99%

“…The pregnancy was complicated by influenza associated with dehydration. Literature (n¼5) [21][22][23] Literature (n¼8) [25][26][27][28] …”

Section: Casementioning

confidence: 99%

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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“…Mental, psychomotor and growth retardation as well as craniofacial anomalies, hypotonia, hypoplastic genitalia, spina bifida and feeding difficulties are significant issues in individuals carrying Xq26-q27 duplications. 10,[12][13][14][15][16] Cryptorchidism is an additional clinical feature present in patients with larger duplications that affect Xq28 region (Table 1; Figure 3), which suggests that the gene responsible for this pathology might be located at the Xq28. Given the relatively small size of the duplication we present here, it could help to identify the genes responsible for the phenotype associated with distal Xq duplications.…”

Section: Discussionmentioning

confidence: 99%

“…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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A familial Xp+ chromosome, dup (Xq26.3-->qter).

Abstract: A maternally transmitted Xp + chromosome was associated with an abnormal

Cited by 32 publications

References 18 publications

X inactivation phenotype in carriers of Pelizaeus-Merzbacher disease: skewed in carriers of a duplication and random in carriers of point mutations

X inactivation phenotype in carriers of Pelizaeus-Merzbacher disease: skewed in carriers of a duplication and random in carriers of point mutations

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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