Familial pericentric inversion of chromosome 12

Summary A pericentric inversion in one of the chromosomes 12, found in two families living in the same region, is deseribed. This inversion was detected during routine chromosomal analysis in two separate laboratories. The breakpoints were at 12p112 and 12q13. The inverted segment represented approximately 20% of the length of chromosome 12. Twenty nine descendants of carriers of the inversion were investigated, and the inversion was present in 23 of them. The other six descendants showed a normal karyotype. After correction for sample bias with the single selection scheme, a segregation ratio of 3:1 was estimated, indicating that the inverted chromosome 12 was preferentially transmitted. All the carriers of the inversion were phenotypically normal, without noticeable fertility disturbances.     

Mosaic pericentric inversion of chromosome 2

A pericentric inversion of chromosome number 2 in mosaic with a normal cell line is reported in a 8-year-old boy associated with slight dysmorphic syndrome and moderate mental handicap.     

Molecular characterization of the pericentric inversion of chimpanzee chromosome 11 homologous to human chromosome 9

In addition to the fusion of human chromosome 2, nine pericentric inversions are the most conspicuous karyotype differences between humans and chimpanzees. In this study we identified the breakpoint regions of the pericentric inversion of chimpanzee chromosome 11 (PTR 11) homologous to human chromosome 9 (HSA 9). The break in homology between PTR 11p and HSA 9p12 maps to pericentromeric segmental duplications, whereas the breakpoint region orthologous to 9q21.33 is located in intergenic single-copy sequences. Close to the inversion breakpoint in PTR 11q, large blocks of alpha satellites are located, which indicate the presence of the centromere. Since G-banding analysis and the comparative BAC analyses performed in this study imply that the inversion breaks occurred in the region homologous to HSA 9q21.33 and 9p12, but not within the centromere, the structure of PTR 11 cannot be explained by a single pericentric inversion. In addition to this pericentric inversion of PTR 11, further events like centromere repositioning or a second smaller inversion must be assumed to explain the structure of PTR 11 compared with HSA 9.     

Correlation of the clinical phenotype with a pericentric inversion of chromosome 9]

Pericentric inversion of chromosome 9 is one of the most common structural balanced chromosomal aberrations. It is considered as a paraphysiological variant of a normal karyotype and it is possible to find it as occasional report in healthy subjects. In the last ten years different signals have appeared in literature, concerning carriers of pericentric inversion of chromosome 9, who showed different anomalies of the clinical condition. Today it is difficult, because of the rarity of the data to establish if a true correlation exists between phenotypical anomalies in the subjects studied and the pericentric inversion, or if they are only casual associations. We are trying to find possible correlations between the chromosomal rearrangements and eventual congenital defects. We describe 11 subjects with pericentric inversion of chromosome 9 examined for the presence of dysmorphic signs, mental retardation and repeated miscarriage.     

A pericentric inversion in the cattle Y chromosome

Sixteen male Podolian cattle, two sires and their 14 male offspring, were investigated cytogenetically on the basis of a female-like phenotype found in one of them. Eleven male offspring, including the one with female traits, and one of the two sires were found to carry an abnormal Y chromosome which originated from a pericentric inversion of the proximal half of the Yq arm (Yq11-->q12.2), as demonstrated by both banding and FISH mapping techniques with Y-specific molecular markers.     

Association of pericentric inversion of chromosome 9 and reproductive failure in ten unrelated families.

A pericentric inversion of chromosome 9 has been detected in 10 unrelated families. The break points are identical and the inversions involved the heterochromatic segment. The effects of inversion of chromosome 9 on different aspects of reproductive failure are discussed.     

Recombinant chromosome as a result of pericentric inversion of X chromosome

Summary A structural X chromosome abnormality was found in the karyotype of a tall patient with gonadal dysgenesis and with no extragenital anomalies. Based on her mother's karyotype, which showed a pericentric inversion of the X chromosome: 46,X,inv(X)(p22q24), as well as from G and R banding, we concluded that the abnormal X chromosome of our patient was a recombinant chromosome that had originated as a result of one crossing over in the inversion loop during gametogenesis in her mother. The recombinant X chromosome had a partial deletion of Xq and a partial duplication of Xp: 46,X,rec(X),dup p,inv(X)(p22q24). After BUDR incorporation, the abnormal X chromosome of the patient and that of her mother showed a late replication. The karyotype-phenotype correlation and the nonrandom inactivation of the inverted X chromosome in the mother are discussed.     

Recombinant chromosome 14 due to maternal pericentric inversion

Chromosome 14 is often involved in various chromosome rearrangements, most of them balanced. Human chromosome 14 is acrocentric, so its pericentric inversions are extremely rare (only few cases have been described in the literature). Here we report on a boy with congenital malformations and recombinant chromosome 14 inherited from his mother carrying a pericentric inversion. The proband's G-banded chromosome analysis revealed derivative chromosome 14. Comparative genomic hybridization analysis identified duplication of the terminal part of chromosome 14q ish cgh dup(14)(q32.1qter). This abnormality has been confirmed by custom BAC FISH analysis. His mother's karyotype was 46,XX,inv(14)(p11.2q32.1).     

Balanced and unbalanced pericentric inversion of a chromosome 14

Summary Three males with a 46,XX karyotype are described. In two of them, evidence of a Y-containing line was found. In the first case, 1 of 500 lymphocyte metaphases was 47,XXY. In the second, 1 of 400 oral mucosa cells contained a Y body. The proportion of low-grade XX/XXY mosaics found among XX males now stands at about 17%.     

A pericentric inversion in an X chromosome in the cow

Cytogenetic examination of a cow with some fertility problems showed a pericentric inversion in an X chromosome. Phenotype and milk production of the cow were not affected by this condition. A review of the literature concerning inversions of cattle chromosomes is presented.     

Analysis of crossing-over in a family with translocation 9;10 involving a chromosome 9 with a pericentric inversion

Summary The presence of two markers on chromosome 9, both a balanced reciprocal translocation and an inversion, allows morphologic demonstration of recombination between the normal and rearranged homologues. In the family under discussion 50% of the progeny studied (two of four) received a translocated 9 without the inversion from a parent with a translocated and inverted 9, indicating crossing-over between members of the chromosome 9 pair. Thus the morphology of the chromosomes allows a recombinat event which is normally invisible to be seen cytologically. Theoretically after crossing-over the balanced reciprocal translocation heterozygote results from adjacent-1 segregation and unbalanced derivative chromosome combinations from alternate segregation. Therefore it cannot be assumed that the balanced progeny necessarily result from alternate segregation and the unbalanced from adjacent-1. The prenatal diagnostic studies presented in this report also show that chromosome analysis of other family members is required when the recombination between homologues produces differences in chromosome morphology between parent and fetus.     

A large pericentric inversion of human chromosome 8.

A large pericentric inversion, inv(8) (p11q24), was ascertained in a male investigated because his wife had had repeated miscarriages. The inversion segregated in 3 generations of the family, and no chromosomally unbalanced offspring were detected. The miscarriage and the inversion could not be causally related.     

Sperm chromosome analysis of a man heterozygous for a pericentric inversion of chromosome 3

Using a procedure in which human sperm were allowed to fertilize zona-free golden hamster (Mesocricetus auratus) eggs in vitro, the sperm chromosomes of a man heterozygous for inv(3) (p11q11) were analyzed. When the chromosomes were Q-banded, the inverted chromosome had the bright centromeric band on the short arm rather than on the long arm, as was seen in the normal No. 3. One hundred and eleven sperm chromosome spreads were examined, of which 64 contained the normal chromosome and 47 the inverted one. This was not significantly different from the expected 1:1 ratio. No sperm containing a chromosome imbalance caused by a crossover within the inversion were seen. Ten (8.1%) of the sperm contained chromosome abnormalities unrelated to the inversion. The ratio of X- to Y-bearing sperm was 55:45.     

Sperm chromosome analysis of a man heterozygous for a pericentric inversion of chromosome 20

Summary The sperm chromosomes of a man heterozygous for inv(20)(p13q11.2) were analyzed. Twenty-six sperm chromosome complements were examined, of which fourteen contained the normal chromosome, and twelve the inverted chromosome. None of the sperm complements contained a recombinant chromosome 20. The frequency of structural chromosomal aberrations unrelated to the inversion was 11.5% (3/26). Numerical aberrations were not observed. The percentages of X- and Y-bearing sperm were 56% and 44%, respectively, which was similar to the expected 11 ratio.