A neocentromere in the DAZ region of the human Y chromosome

Floridia, Giovanna; Gimelli, Giorgio; Zuffardi, Orsetta; Earnshaw, William C.; Warburton, Peter E.; Tyler‐Smith, Chris

doi:10.1007/s004120000081

Cited by 21 publications

(20 citation statements)

References 40 publications

(41 reference statements)

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“…Its mitotic stability and presence in amniocytes (frequency, 50%) and blood (70%) support the notion of a functional neocentromere on the marker. There have been examples of other NMCs satisfying all criteria of antibody staining and showing mitotic instability (cytogenetic mosaicism) [Depinet et al, 1997;Floridia et al, 2000;Reddy et al, 2000]. Possible explanations may include 1) postzygotic formation of the SMC (a mechanism predicted with many supernumerary ring markers and with many inverted duplications), 2) postzygotic formation of the neocentromere in an acentric fragment, or 3) mitotic loss, a well-known mechanism with ring chromosomes occasionally forming double rings.…”

Section: Discussionmentioning

confidence: 94%

“…However, in recent years some 50 cases of SMCs without detectable alphoid DNA sequences have been reported, with the neocentromere located on chromosomes Xq and Y (5 cases); 1p, 1q, 2p, 3p, and 3q (5 cases); 4q, 8p, and 8q (2 cases); 9p (2 cases); 10p and 10q (3 cases); 11q and 13q (10 cases); 14q and 15q (8 cases); 17q, 19, 20p, and 21q [Barbi et al, 2000;Floridia et al, 2000;Higgins et al, 2000;Levy et al, 2000;Reddy et al, 2000;Rowe et al, 2000; (38 cases); Warburton et al, 2000 (40 cases); Morrissette et al, 2001]; or on chromosomal material not representing any human chromosome [Mackie Ogilvie et al, 2001]. Eighteen of these neocentric marker chromosomes (NMCs) were isochromosomes of the distal long arm of chromosome 13 or 15; therefore, the most common mechanism for the formation of NMCs in man is the de novo inverted duplication of the distal segments of chromosomes [Choo, 1997;Warburton et al, 2000].…”

Section: Introductionmentioning

confidence: 97%

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Two new cases of analphoid marker chromosomes

Spiegel

Hickmann²,

Senger

et al. 2002

American J of Med Genetics Pt A

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Supernumerary marker chromosomes (SMCs) without detectable alphoid DNA represent a rare and interesting class of rearranged marker chromosomes. These SMCs are predicted to have a neocentromere and have been referred to as neocentric marker chromosomes (NMCs). We report the molecular cytogenetic characterization of two new cases of neocentromere-containing chromosomes, one on 1q43-44 and one on 15q26. Both cases were examined using fluorescence in situ hybridization (FISH) with various alpha-satellite DNA probes, and no alphoid DNA was detected. In case 1, the NMC originated from the distal long arm of chromosome 1 by chromosomal microdissection and reverse painting. This marker lacked detectable chromosome 1q subtelomeric sequences, and therefore appeared to be a small ring chromosome. After genetic counseling with a high risk for a MCA/MR syndrome (trisomy 1q43 --> q44), the family continued the pregnancy. At age 6 months, the infant demonstrated no congenital or developmental anomalies. This is the first published example of a NMC derived from chromosome 1q. The marker may be one of the smallest, if not the smallest, human NMC reported to date. In case 2, fetal ultrasonography indicated a complex heart defect (abnormal return of lower vena cava, atrial septum malformation) and bilateral hydronephrosis. Molecular cytogenetic analysis showed an inverted duplication of the distal long arm of chromosome 15 (tetrasomy 15q24 --> qter). The pregnancy was terminated. Autopsy demonstrated polycystic left kidney and dysplastic right kidney. Case 2 represents the ninth report of a neocentromere on distal chromosome 15q, suggesting that this region may possibly especially support the formation of neocentromeres.

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Section: Discussionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 97%

Two new cases of analphoid marker chromosomes

Spiegel

Hickmann²,

Senger

et al. 2002

American J of Med Genetics Pt A

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“…CENP-B binds a subset of alpha-satellite DNA (55) and has been shown to accumulate below the kinetochore (56), within the region of the active centromere. In addition to CENP-B, topoisomerase II enzymatic activity has been localized within the active centromere site (29,30). The unique chromatin environment created by the centromere-specific histone, CENP-A, combined with the activity of CENP-B and topoisomerase II may contribute to the apparent promiscuity of centromeric regions by confining the proposed expansion events and insertion of transposable elements to functionally active centromeric DNA.…”

Section: Discussionmentioning

confidence: 99%

“…The sites of human kinetochore assembly (29,30) are largely devoid of interspersed repeats (10,17), span large intervals (15,57), and have an underlying sequence periodicity, all of which facilitate the formation of higher-order structures that might be necessary for kinetochore interactions (4). Insertion of active LINEs would disrupt that periodicity, potentially compromising centromere activity and requiring a compensatory expansion of centromeric DNA (58).…”

Section: Discussionmentioning

confidence: 99%

Progressive proximal expansion of the primate X chromosome centromere

Schueler

Dunn²,

Bird³

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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Previous studies of the pericentromeric region of the human X chromosome short arm (Xp) revealed an age gradient from ancient DNA that contains expressed genes to recent human-specific DNA at the functional centromere. We analyzed the finished sequence of this human genomic region to investigate its evolutionary history. Phylogenetic analysis of >1,500 alpha-satellite monomers from the region revealed the presence of five physical domains, each containing monomers from a distinct phylogenetic clade. The most distal domain contains long interspersed nucleotide element repeats that were active >35 million years ago, whereas the four proximal domains contain more recently active long interspersed nucleotide element repeats. An out-of-register, unequal recombination (i.e., crossover) detected at the edge of the X chromosomespecific alpha-satellite array (DXZ1) may reflect the most recent of a series of punctuating events during evolution that resulted in a proximal physical expansion of the X centromere. The first 18 kb of this array has 97-99% pairwise identity among all 2-kb repeat units. To perform more detailed evolutionary comparisons, we sequenced the junction between the ancient DNA of Xp and the primate-specific alpha satellite in chimpanzee, gorilla, orangutan, vervet, macaque, and baboon. The striking conservation found in all cases supports the ancestral nature of the alpha satellite at this location. These studies demonstrate that the primate X centromere appears to have evolved through repeated expansion events occurring within the central, active region of centromeric DNA, with the newly added sequences then conferring centromere function.evolution ͉ alpha satellite ͉ comparative genomics ͉ genome sequencing

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“…Thus, in the two reported cases of inverted duplication neocentric Y chromosome derivatives, the neocentromere appears to be found in the euchromatic DNA at or near the breakpoint [Floridia et al, 2000] (Fig. 2b,c).…”

Section: Discussionmentioning

confidence: 80%

Identification of a neocentromere in a rearranged Y chromosome with no detectable DYZ3 centromeric sequence

et al. 2002

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An 18-year-old woman was evaluated because of primary amenorrhea and hypogonadism. Chromosome analysis from peripheral blood lymphocytes revealed a nonmosaic 46,X,+mar constitution. The marker was shown to be a rearranged Y chromosome consisting of an inverted duplication of the long arm: rea(Y)(qter-q11::q11-qter). Deletion mapping analysis with Y-specific STS showed that the marker lacked Yp and Y-centromeric (DYZ3) sequences, but it was positive for Yq sequences tested. Fluorescence in situ hybridization analysis with Y and X chromosome centromeric and pancentromeric probes showed no hybridization signals. The marker chromosome is present in 100% of the cells; therefore, it is mitotically stable despite the absence of DYZ3 centromeric sequence. Hybridization with CENP-A and CENP-C specific antibodies localized a neocentromere close to the breakpoint.

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A neocentromere in the DAZ region of the human Y chromosome

Cited by 21 publications

References 40 publications

Two new cases of analphoid marker chromosomes

Two new cases of analphoid marker chromosomes

Progressive proximal expansion of the primate X chromosome centromere

Identification of a neocentromere in a rearranged Y chromosome with no detectable DYZ3 centromeric sequence

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