Meiotic consequences of pericentric inversions of chromosome 13

Chromosomal analyses of 1510 couples who have experienced recurrent spontaneous abortions

In this retrospective study, karyotype results of 1510 couples with a history of recurrent spontaneous abortion were evaluated. The study was conducted at Balcalı Hospital in Adana region of Turkey. For all cases, peripheral blood lymphocytes were cultured for chromosome study using the standard method. Chromosome aberrations were detected in 62 couples (4.1% of all couples). At an individual level, chromosome aberrations were found in a total of 65 cases (41 females and 24 male cases), with structural chromosomal aberrations in 58 cases including balanced translocations in 30 cases, Robertsonian translocations in 12 cases, deletions in seven cases, inversions in nine cases and numerical chromosome aberrations in seven cases. The results of the study indicated that structural aberrations, particularly translocations, were the most common type of aberration observed among couples who had experienced recurrent spontaneous abortions and that these couples might benefit from cytogenetic analyses.

Characterization of a familial balanced rec(13) in a child with mild MR and his half-sibling with two structurally rearranged chromosomes 13

In this report, we describe a 7-year-old child with mild mental retardation, developmental delay, and learning disabilities. His karyotype contained a rearrangement of chromosome 13, which appeared to include a duplication of 13q31-qter and a deletion of 13p12-pter regions. The chromosomal origin of the additional material was confirmed by fluorescence in situ hybridization (FISH) using a whole chromosome painting probe specific for chromosome 13. Family studies showed that his mother carried a balanced inversion of chromosome 13 and that his half-brother carried the balanced pericentric inversion of chromosome 13 from his mother as well as another structural rearrangement involving chromosome 13 presumably from his father. The findings from this study suggested that the proband's abnormal 13 resulted from an unbalanced crossing-over between the normal and maternal inverted chromosome 13.

Chromosome inversions and a novel chromosome insertion associated with recurrent miscarriages in South India

The aim of the present study was to investigate the contribution of chromosomal abnormalities and the frequency of a particular type of aberration in couples of South Indian origin with recurrent miscarriages. A total of 160 couples with recurrent miscarriages were analyzed using Giemsa-Trypsin-Giemsa (GTG) banding and Fluorescence in situ hybridization (FISH) wherever necessary. Chromosomal abnormalities were detected in 18 individuals representing 11.25% of the samples analyzed. Present study describes majority of the cases with chromosome inversions found to be common among the referred couples. Among the abnormal karyotypes, we report for the first time an unique case of chromosome insertion in a woman with the karyotype 46,XX,ins(12;6)(q24.2;q23q25) associated with recurrent miscarriages. The overall incidence of abnormalities and the predominance of chromosome inversions indicates to physicians that routine chromosome analysis of infertile couples of South Indian origin should be essentially considered before the planning of Intra Cytoplasmic Sperm Injection (ICSI), and also the priorities for cytogenetic screening in individual cases should be established.

Case report of rec(7)dup(7q)inv(7)(p22q22) and a review of the recombinants resulting from parental pericentric inversions on any chromosomes

We report a rare case of duplication for 7q22 --> 7qter and deletion for 7p22 --> 7pter, resulting from a meiotic recombination of a paternal pericentric inversion, inv(7)(p22q22). The newborn boy had the 7q trisomy syndrome. In addition, the diagnosis of chondrodysplasia punctata was made from lumbar and hand X-ray films taken soon after birth. Only two cases of rec(7)dup(7q), both in a single family, have been reported previously. We review 133 offspring with recombinations resulting from pericentric inversions on any chromosomes reported between 1981 and 1995. Of the 133 cases, 110 had a long-arm duplication and short-arm deletion, while only 23 had a short-arm duplication and long-arm deletion. In 85 of the 133 cases, the mother was an inversion carrier (five carriers had two affected offspring), and in 46, the carrier was a father (one carrier had three affected offspring). Kaiser [Hum Genet 1984;68:1-47] reviewed 63 offspring with recombinations derived from a parental pericentric inversion reported between 1972 and 1981. In both surveys, recombinations resulting from pericentric inversions of chromosomes 1, 12, 19, and Y were not found.

Elucidation of the centromere involvement in an inversion (13) by fluorescent in situ hybridisation

A newborn infant with phenotypic features of trisomy for distal 13q was found to have recombinant inversion duplication involving the (13)(q22-->qter) region. Parental karyotypes showed that the mother had a normal 46,XX complement and the father had an apparently balanced pericentric inversion of a chromosome 13. Because of the unusual nature of the inversion, the exact position of the centromere on the father's inverted chromosome 13 was difficult to assign by GTG banding, even on prometaphase chromosomes. CBG and NOR banding were not informative in determining the location of the centromere. Fluorescent in situ hybridisation with an alpha satellite DNA probe for D13Z1/D21Z1 helped in confirming the exact position of the centromere in the rearranged paternal chromosome. Thus, the origin of the proband's abnormal chromosome 13 was clarified.

Segregation of inverted chromosome 13 in families ascertained through liveborn recombinant offspring

In humans pericentric inversions are rare structural chromosome abnormalities. Reproductive consequences of inversion heterozygosity depend upon many variables such as the chromosomes involved, the location of breakpoints, frequency of crossovers in the inverted segment, functional impairment of the gametes produced, and the viability of unbalanced zygotes that form. Therefore, each pericentric inversion may be studied as a unique mutation. This paper analyzes the segregation of inversion 13 chromosomes resulting from breaks at bands 13p12 and 13q21/22 in 11 apparently unrelated families. Ten of these families were ascertained through malformed fetuses or infants with a recombinant 13 duplication q, deletion p chromosome.

Phenotype-karyotype correlation in patients trisomic for various segments of chromosome 13

Analysis of clinical and cytogenetic findings taken from 62 published cases of partial trisomies of chromosome 13 showed that 15 had partial trisomy for the proximal long arm and 47 had trisomy for the distal long arm. Persistence of fetal haemoglobin (Hb F), increased projections of polymorphonuclear leucocytes (PMN), depressed nasal bridge, cleft lip/palate, and clinodactyly were more frequent in patients with proximal trisomy 13. In the distal trisomy group, the common features included haemangioma, bushy eyebrows, long curled eyelashes, prominent nasal bridge, long philtrum, thin upper lip, highly arched palate, and hexadactyly. In addition, several other features were common to both the groups, often showing inconsistency even when the same segment was in trisomy. The influence of the second aneusomy as the most likely cause for such inconsistent and overlapping phenotypes is discussed in view of the fact that 42 of 62 cases were derived from a balanced translocation carrier parent.

Pericentric inversions. Problems and significance for clinical genetics

A review is given of the incidence, cytogenetics, and biologic relevance of pericentric inversions (pii). In 251 cases in the literature and our patients, 96 different inversion forms with different breakpoints are found. Eighteen of these cases have been observed several times in unrelated families; they are classified as types. The problem of pii in the heterochromatic regions of chromosomes 1 and 9 is especially emphasized and the investigations required are pointed out. The significance of the individual pii is checked with regard to their behavior in meiosis and their phenotypical relevance. An approximately 1:1 segregation is found. Fertility, stillbirth, and rates of abortion are not statistically altered. The gonadal findings available at present in man are reported and commented on. The occurrence of aneusomic recombinants among the live offspring of carriers shows a marked dependence on the length of the relative inversion segments. Since these are distinctly below average in inversion types, they only result in recombinants in exceptional cases. Certain pointers to an above-random common occurrence of other chromosomal aberrations are not found in families with pii. A correlation between pii and clinical symptoms likewise cannot be detected. However, in this connection it is pointed out that trisomic mosaics were observed jointly with pii(9) and pii(22). The review is completed by a brief examination of the literature concerning the significance of pii in evolution.

The phenotype in partial 13q trisomies, apropos of a familial (13;15)(q22;q26) translocation

A 12 month-old male patient with a karyotype 46,XY,-15,+der(15),t(13;15)(q22;q26)pat is presented. His stillborn sib showed malformations compatible with the 13q deletion syndrome, probably due to a 46,XY,der(13) karyotype. Phenotypic analysis of 41 cases from the literature with partial distal 13q (D13q) trisomies indicate that the segment 13q22----qter in trisomy with or without another concomitant aneusomy is sufficient to produce the majority of the trisomy 13 syndrome features, some of which (cleft palate, increased HbF and projections in PMN) are present in different non-overlapping partial 13q trisomies. About 82% of the D13q trisomies are inherited, more frequently from the mother.

Trisomy 18 phenotype in a patient with an isopseudodicentric 18 chromosome

We report a female patient with a typical trisomy 18 phenotype who has a 46,XX, -18, +isopseudodic(18)(p11) karotype. The lack of features of the 18p- syndrome suggests that a significant amount of short arm material is present and that the Turner-like features associated with 18p- may be determined by monosomy for 18p11. The phenotype-genotype correlations in abnormalities affecting chromosome 18 are reviewed.

Familial pericentric inversion (13) detected by antenatal diagnosis

A recombinant rec (13), dup q chromosome was diagnosed in a 17-week fetus following amniocentesis. Subsequently, a familial pericentric inversion of chromosome 13 was seen to be segregating in the family and the same recombinant 13 was present in a mentally retarded aunt of the fetus. The clinical features of the carriers of the inversion product are discussed with reference to previous cases.