Pericentric inversion of “fluorescent” segment in chromosome No. 3

During a short time span we identified 3 unrelated cases of pericentric inversion of the “fluorescent” segment in one chromosome No. 3. All 3 propositae were mentally defective female patients of a mental hospital; 1 case was familial with phenotypically normal father and grandfather.     

Pericentric inversion in chromosome 2 without phenotypic effect

A subject with pericentric inversion of chromosome 2: 46, XY, inv(2) (p11q13) is described. All the family members which present the same inversion are clinically normal     

Pericentric inversion in human chromosome 8 and spherocytosis

A cytogenetic study of a patient revealed a pericentric inversion in chromosome 8, and spherocytes in 10% of cells, in a routine blood smear. The critical portion which affected the expression of spherocytosis appeared to be localized at 8p22-8q21. The mother's karyotyping showed the transmission of the inversion to the child.     

Pericentric inversion of chromosome 19 in three families

Summary Pericentric inversion of chromosome 19 has been found in several members of three unrelated families from a restricted geographical region. In one of the families, an additional pericentric inversion of chromosome 9 was observed. Reproductive problems, multiple abortions in two families and a neonatal death in the third, were present. A review of previously described cases is included, and the genetic risk connected with this type of rearrangement is also discussed.     

Pericentric inversion of chromosome 12; a three family study

Summary A pericentric inversion of chromosome 12 has been followed in three large independently ascertained Danish families. Out of a total number of 52 persons examined, 25 were found to carry the inversion. The break-points in all three families were localized to p13 and q13, resulting in more than one-third of the total length of the chromosomes being inverted. However, no chromosomal aberrations arising because of meiotic crossing-over inside the inverted area have been found among the offspring of the carriers. The percentage of spontaneous abortions among carriers is found to be high, viz. 33%. The segregation rate is calculated to be 0.58, which is not significantly different from an expected segregation rate of 0.5. In family 3, an additional inversion of a chromosome 9 has been found in 4 individuals. Our results are discussed in relation to previous findings and with respect to the genetic counselling of families with pericentric inversions.     

Pericentric inversion of chromosome 1 in three sterile brothers

Summary A pericentric inversion of chromosome 1 was found in three phenotypically normal brothers. The proband consulted for azoospermia. Also, one of his brothers is azoospermic and another one is severely oligozoospermic. G-banding studies indicate that the breakpoints of the inversion are at p13,q25.     

Pericentric inversion of chromosome 13: familial study and review of the literature.

A family is described in which a pericentric inversion of chromosome 13 (13(p11 q22] was discovered after amniocentesis was performed in a patient with a previous stillborn child with multiple congenital abnormalities, and one surviving Down syndrome offspring with the maternal inversion and an additional trisomy 21. No association between pericentric inversion of chromosome 13 and other chromosomal abnormalities was found in the literature. This study discuss the possible involvement of this type of inversion in the occurrence of chromosomal and phenotypic alterations in the carrier offspring, as well as its role in genetic counseling and in the indication of prenatal diagnosis.     

Pericentric inversion of the X chromosome: presentation of a case and review of the literature.

A large pericentric inversion of the X chromosome [inv(X)(p22.31q26.3)] was found to be transmitted in four generations through phenotypically normal males and females. In one female carrier, the inv(X) was late replicating in 70% of lymphocytes and 46% of skin fibroblasts. Steroid sulfatase (STS), an enzyme which normally escapes inactivation has been located to Xp22.32 and, in our case, has been moved to an aberrant position. We have assayed its activity in clones with the inv(X) inactive or the normal X inactive and found no significant differences. Thus, the STS locus escaped X inactivation in both the normal and the inverted X chromosomes. A review of the literature shows that almost half of the breakpoints on the short arm are found at region p22 and we propose that low-copy repetitive DNA segments along the X chromosome are responsible for non-homologous pairing and production of inversions.     

Pericentric inversion of chromosome 2 (p11 q13) in unrelated families (author's transl)]

A pericentric inversion of chromosome 2 has been detected in 4 unrelated families. The break points are identical in band 2p11 and band 2q13. Reproductive history of these couples is analyzed. The pathology of these particular regions of chromosome 2 is discussed.     

Pericentric Y inversion in the general population

Summary Two males with pericentric inversion of the Y chromosomes were found among 1115 males examined for military service. This correlates well with the finding of 2 out of 2615 newborn Danish boys with pericentric Y inversion (Friedrich and Nielsen, 1973). The results of these two studies indicate that the prevalence of pericentric Y inversion in the general population is approximately 1 per 1000.The pericentric Y inversion was found in all male relatives examined. Psychiatric and physical examination revealed no indications of any common aberrations, and there were no suggestions of any family members with other chromosome aberrations.It is concluded that there are no indications that pericentric Y inversion is connected with any deviations in personality and intelligence or with an increased risk of physical disorders or non-disjunction.

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Zusammenfassung Zwei männliche Individuen mit einer perizentrischen Inversion des Y-Chromosoms wurden unter 1115 Männern gefunden, die für den Militärdienst gemustert wurden. Das entspricht der Häufigkeit bei Neugeborenen (2 unter 2615 in Dänemark; Friedrich u. Nielsen, 1973). Beide Untersuchten zusammen deuten auf eine Häufigkeit von ungefähr 1:1000 hin.Die perizentrische Y-Inversion fand sich bei allen untersuchten männlichen Verwandten. Körperliche und psychiatrische Untersuchung ergab keinen Hinweis für irgendeine häufige Störung. Auch ergab sich kein Hinweis auf andere Chromosomenaberrationen bei Familienangehörigen.Offenbar ist die perizentrische Y-Inversion nicht mit irgendeiner Abweichung in Persönlichkeit oder Intelligenz verbunden. Es fehlt auch jeder Hinweis auf ein erhöhtes Risiko für körperliche Störungen oder für Nondisjunction.

     

Pericentric X inversion in dizygotic twins who differ in X chromosome inactivation and menstrual cycle function

Summary A 21-year-old female dizygotic twin was referred for cytogenetic evaluation because of mild mental retardation. Significant history, clinical, and physical findings included irregular menses, mildly coarse facies, and microcornea. Chromosome analysis revealed a pericentric inversion of the X chromosome, 46,X,inv(X)(p11;q22). Her twin who is phenotypically normal was also found to carry the same inversion. The twins differ significantly in X chromosome inactivation and menstrual cycle function.     

Prenatal diagnosis of a rare de novo centromeric chromosome 6 variant

Cytogenetic heteromorphisms are described as heritable variations at specific chromosomal regions without phenotypic effect. Polymorphisms of the size of heterochromatic centromeric regions of chromosomes 1, 9 and 16 have been well documented in humans but only four previous reports described centromeric polymorphism of chromosome 6. We present a prenatal diagnosis of a rare de novo centromeric chromosome 6 variant. Cytogenetic and molecular techniques were used to characterize this variant and confirm the de novo nature of this event. This case illustrates the importance of reporting unusual variant chromosomes for genetic counseling and for determination of the frequency of variant chromosomes in the general population.     

Structural aberration in chromosome No. 2

Summary Two males with gaps and breaks in a chromosome No. 2, at approximately 2q12 are presented. It is concluded that this aberration most probably has no deleterious effect on physical or mental development.

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Zusammenfassung Es wurden zwei Männer mit gaps und Brüchen in einem Chromosomen Nr. 2, annähernd bei 2q12, beobachtet. Diese Aberration hat sehr wahrscheinlich keine nachteilige Wirkung auf die körperliche oder geistige Entwicklung.

     

A second case of (de novo) paracentric inversion of the short arm of the X chromosome

A de novo paracentric inversion of the short arm of an X chromosome (p11.2p22.1) was observed in a 17-year-old girl studied because of primary amenorrhea and a Turner phenotype. To our knowledge this is only the second case of a paracentric inversion of the X chromosome short arm reported, the first having been briefly described in 1982, in a young lady with the Turner phenotype. In spite of its balanced appearance, there is little doubt that this rearrangement is the cause of the phenotypic anomalies of the patient, probably as the result of gene(s) modification(s) at the breakpoints on the X chromosome, or because the inverted gene sequence resulted in modifications by position effect. It has become increasingly difficult to recognize obvious phenotype-genotype correlations in Turner syndrome, given the multiplicity of chromosome rearrangements--some of them quite subtle--which are associated with ovarian dysgenesis.