Complex chromosomal rearrangement and multiple spontaneous abortions

Derivative chromosome 11 in a child resulting from a complex rearrangement involving chromosomes 3, 6 and 11 in father: Significance of parental karyotyping

The presence of derivative chromosome in a child with phenotypic features necessitates the need of parental karyotyping to ascertain the exact amount of loss or gain of the genetic material. The aim of this study was to emphasize the importance of parental karyotyping. Cytogenetic evaluation of the proband and his father were carried out at Laboratory. Cytogenetic analysis was performed on phytohemagglutinin stimulated cultures. The derivative chromosome 11 in proband was ascertained to have additional material from chromosome 6p arising from complex chromosomal rearrangement in the father. Karyotyping is the basic, cost-effective preliminary investigation in a child with mental subnormality or congenital anomalies.

A 14-year follow-up of a case detected prenatally of partial trisomy 13q21.32-qter and monosomy 18q22.3-qter as a result of a maternal complex chromosome rearrangement involving chromosomes 6, 13, and 18

A balanced complex chromosome rearrangement (CCR) involving three chromosomes is rare and may lead to different types of aneuploid germ cells. We report here a 14-year follow-up of a boy with a karyotype defined as 46,XY,der(18)t(6;13;18)(q21;q21.32;q22.3).ish der(18)(13qter+,18qter-) characterized by multiple congenital abnormalities, including distinctive minor facial anomalies, short neck, abnormalities of the extremities, anogenital abnormalities, flexion contractures, especially at extremities, and severe mental and growth retardation. Chromosome analysis in the mother showed a CCR involving chromosomes 6, 13, and 18. This CCR was the result of a three-break rearrangement, and the derivative chromosome 13 consisted of parts of chromosomes 18 and 13. The karyotype of the child was not balanced, and resulted in partial trisomy for 13q and partial monosomy for 18q detected prenatally by conventional and molecular cytogenetics. Although such a karyotype and its phenotype have not previously been reported, we have compared the clinical and cytogenetic data from our patient with previously described cases of partial trisomy 13q and monosomy 18q despite different break points. We are presenting a new CCR in a woman with normal phenotype with a history of four early abortions and a long follow-up of her malformed newborn with partial 13q trisomy and 18q monosomy.

A constitutional complex chromosome rearrangement involving meiotic arrest in an azoospermic male: Case report

Complex chromosome rearrangements are rare aberrations that frequently lead to reproductive failure and that may hinder assisted reproduction. A 25-year-old azoospermic male was studied cytogenetically with synaptonemal complex analysis of spermatocytes from a testicular biopsy and fluorescence in situ hybridization (FISH) of lymphocytes. The spermatocytes showed a pentavalent plus a univalent chromosome. Cell death occurred mainly at advanced pachytene stages. The sex chromosomes were involved in the multiple, as shown by their typical axial excrescences. Two autosomal pairs, including an acrocentric chromosome (15), were also involved in the multiple. FISH allowed the definite identification of all the involved chromosomes. An inverted chromosome 12 is translocated with most of one long arm of chromosome 15, while the centromeric piece of this chromosome 15 is translocated with Yqh, forming a small marker chromosome t(15;Y). The euchromatic part of the Y chromosome is joined to the remaining piece of chromosome 12, forming a neo-Y chromosome. The patient shows azoospermia and a normal phenotype. The disruption of spermatogenesis is hypothetically due to the extent of asynaptic segments and to sex-body association during pachytene. This CCR occurred 'de novo' during paternal spermatogenesis. Meiotic analysis and FISH are valuable diagnostic tools in these cases.

A de novo complex chromosomal rearrangement with a translocation 7;9 and 8q insertion in a male carrier with no infertility

A de novo complex chromosomal rearrangement (CCR) involving chromosomes 7, 8 and 9 in a male carrier was ascertained through his healthy wife's recurrent spontaneous abortions. Six pregnancies over eight years resulted in four spontaneous abortions and two livebirths who died perinatally due to abnormal vital signs. Cytogenetic analyses utilizing high resolution chromosome banding technique showed a deletion of band in a der(7) chromosome and an extra band inserting at 8q21.2. Another extra band was also observed at the band 9p24, but it could not be karyotypically determined. Fluorescent in-situ hybridization using chromosome 7 and 8 specific microdissected library as probes confirmed the insertion of a segment from the translocated chromosome 7 into a chromosome 8, and additionally revealed a translocation between chromosomes 7 and 9. The karyotype of the CCR carrier was determined as 46,XY,t(7;9)(q22;p24),ins(8;7)(q21.2;q22q32).ish der(9)(wcp7+);ins(8;7)(wcp8+,wcp7+). Comparing with previously reported male CCR carriers with our case, we conclude that male CCR carriers may not always present with infertility or subfertility phenotypes. This may suggest that rare transmission of male carriers could result from abnormal chromosomal rearrangements during meiosis and gametogenesis in addition to frequent infertility.

A de novo complex chromosomal rearrangement with nine breakpoints characterized by FISH in a boy with mild mental retardation, developmental delay, short stature and microcephaly

A de novo complex chromosome rearrangement (CCR) involving chromosomes 1, 6, 7, 15 and Y was detected in a boy with mental retardation, short stature, and microcephaly. Fluorescence in situ hybridisation (FISH) with whole chromosome painting libraries, band-specific cosmids and telomeric probes was essential for the characterisation of the rearrangement. The CCR was shown to be the result of at least nine chromosomal breaks and involved the alternating insertion of two segments of the short arm of chromosome 1 and two segments of the long arm of chromosome 6 into a novel derived chromosome 7. A non-reciprocal translocation between the distal short arm of the same chromosome 7 and the distal long arm of the Y chromosome was also found, together with a paracentric inversion of the long arm of chromosome 15. The only detectable imbalance was a deletion of the heterochromatic Yq telomeric region. FISH investigations in this case have revealed an additional complexity in this CCR, which has implications for reproductive risk assessment and genetic counselling.

Complex chromosomal rearrangement in a woman with multiple miscarriages

We report on a 23-yr-old healthy female with repeated miscarriages and a de novo complex chromosomal rearrangement (CCR) involving chromosomes 1, 2, 5 and 11 with 5 breakpoints. A review of cases reported in the last five yr is provided.