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G Schwanitz

Publications and source records attributed to G Schwanitz.

At least 37 records · Page 2Linked to original sources
PubMed1998

Increased frequency of congenital chromosomal aberrations in female partners of couples undergoing intracytoplasmic sperm injection.

We evaluated the frequency of congenital chromosomal aberrations in a sample of 305 couples included in an intracytoplasmic sperm injection (ICSI) programme. Twenty individuals (3.3%) with congenital chromosomal abnormalities could be identified. The following types of abnormalities were observed: reciprocal translocations (n = 7), Robertsonian translocations (n = 3), inversions (n = 3), other structural aberrations (n = 4) and sex chromosome aberrations (n = 3). The rate of chromosomally abnormal males (10/305, 3.3%) lay within the expected range for patients with reduced semen quality. Surprisingly, 50% (10/20) of all abnormal karyotypes were contributed by the female partner of ICSI patients. These data confirm the higher incidence of chromosomal aberrations in infertile populations as compared with the baseline population risk. Additionally, the data imply that in some cases of male factor infertility a hidden female chromosomal factor may be present, which cannot be identified by standard clinical evaluation. In conclusion, we recommend chromosomal analysis in both partners of couples undergoing ICSI treatment.

Adult↗
PubMed1998

Analysis of a familial three way translocation involving chromosomes 3q, 6q, and 15q by high resolution banding and fluorescent in situ hybridisation (FISH) shows two different unbalanced karyotypes in sibs.

We report on a familial three way translocation involving chromosomes 3, 6, and 15 identified by prometaphase banding and fluorescence in situ hybridisation (FISH). Two mentally retarded sibs with different phenotypic abnormalities, their phenotypically normal sister and mother, and two fetuses of the phenotypically normal sister were analysed. The terminal regions of chromosomes 3q, 6q, and 15q were involved in a reciprocal translocation, in addition to a paracentric inversion of the derivative chromosome 15. Conventional cytogenetic studies with high resolution GTG banding did not resolve this rearrangement. FISH using whole chromosome paints (WCPs) identified the chromosomal regions involved, except the aberrant region of 3q, which was undetectable with these probes. Investigation of this region with the subtelomeric FISH probe D3S1445/D3S1446 showed a balanced karyotype, 46,XX,t(3;15;6) (q29;q26.1;q26), inv der(15) (q15.1q26.1) in two adult females and one fetus. It was unbalanced in two sibs, showing two different types of unbalanced translocation resulting in partial trisomy 3q in combination with partial monosomy 6q in one patient and partial trisomy 15q with partial monosomy 6q in the other patient and one fetus. These represent apparently new chromosomal phenotypes.

Adult↗
PubMed1998

A case of de novo translocation 16;21: trisomy 16q phenotype and origin of the aberration.

A male newborn with severe congenital abnormalities is described with a de-novo translocation 16;21 resulting in trisomy 16q. Clinical features were consistent with trisomy 16q cases reported in the literature. Molecular analysis indicate a formation mechanism of the rearrangement restricted to postzygotic mitosis. Therefore, a low recurrence risk for the parents could be delineated.

Abnormalities, Multiple↗
PubMed1997

Report of two new cases of Pallister-Killian syndrome confirmed by FISH: tissue-specific mosaicism and loss of i(12p) by in vitro selection.

Tissue-specific mosaic distribution of an additional isochromosome 12p is the characteristic chromosomal aberration in Pallister-Killian syndrome. Often it is confined to fibroblasts, whereas lymphocytes show a normal karyotype. Two cases are reported in which the distribution of the additional i(12p) was analysed in various tissues. The isochromosomes were characterised by conventional banding technics and fluorescence in situ hybridization (FISH). In the first case, diagnosed prenatally, 4 different tissues were analysed. A direct preparation of chorionic villi (21 gestational weeks) showed an extra marker chromosome in 19% and two additional copies in 3% of the examined cells. In two cultures of amniocytes (17 and 21 weeks), the i(12p) was observed in 23% and 12%, respectively. It was absent in cultured lymphocytes of fetal blood (21 weeks). The fibroblast long-term culture of umbilical cord showed the i(12p) in 100% of metaphases. In the second case of a term infant the i(12p) was diagnosed in cultured lymphocytes (4%) and fibroblasts (93%). Secondary loss of the isochromosome was evaluated by in vitro selection in case 2 analysing metaphases and interphases of fibroblasts in the 1st, 4th and 5th subculture using FISH. The proportion of cells with i(12p) decreased from 93% to 40% and to 28%, respectively. DNA analysis in case 1 showed a maternal meiotic origin of the i(12p). The prenatally detected clinical findings in both cases showed characteristic abnormalities of the Pallister-Killian syndrome.

Chromosome Aberrations↗
PubMed1997

Identification of supernumerary der(20) chromosomes by FISH in three patients.

Small supernumerary marker chromosomes of 3 patients were characterized at the molecular cytogenetic level. Two ring chromosomes and one metacentric marker were shown to be distamycinA/DAPI-negative and did not possess satellite regions after conventional banding techniques. Fluorescence in situ hybridization (FISH) was performed and in all 3 cases the supernumerary markers were shown to be derived from chromosome 20. Phenotypes are described and discussed with respect to karyotypes. Two of the patients are developmentally and/or phenotypically normal. The first patient has a ring chromosome, containing a small amount of euchromatic material; the second patient is the carrier of a small, metacentric and most probably heterochromatic marker. Patient 3 has physical anomalies, including a congenital heart defect and delayed motor development, but is intellectually almost normal. His marker chromosome is a ring containing a small amount of euchromatic material.

Child↗
PubMed1997

Molecular investigation of the parental origin of a de novo unbalanced translocation 13/18.

We report a patient with a de novo translocation 13/18, identified by high-resolution banding. The breakpoints were ascertained by fluorescence in situ hybridisation with whole chromosome 13 and 18 paints. Short tandem repeat typing demonstrated the aberration to be of combined maternal/paternal origin and thereby confirmed its de novo and postzygotic formation. Thus, a gonadal mosaic in one of the parents resulting in a higher recurrence risk could be excluded.

Abnormalities, Multiple↗
PubMed1997

Success of intracytoplasmic sperm injection in couples with male and/or female chromosome aberrations.

This paper reports on results of intracytoplasmic sperm injection (ICSI) in patients in whom constitutional or secondary chromosome aberrations were detected in the male and/or female partner. Out of 434 couples treated by ICSI (590 cycles), 16 couples (3.7%) were affected by constitutional chromosome aberrations and 96 (22.1%) by secondary chromosome aberrations. Constitutional chromosome aberrations were found in eight male and eight female patients. Couples with the aberration in the male showed significantly lower fertilization, implantation and pregnancy rates (P < 0.05). The occurrence of female constitutional chromosome aberrations led to lower fertilization rates but implantation and pregnancy rates were similar to a control group; however, a higher abortion rate was noted. In the group with secondary chromosome aberrations, 22 males and 59 females carried an abnormality and in 15 couples, both partners. Compared to the remaining (unaffected) 322 couples, fertilization and embryo transfer rates were reduced but implantation rates and pregnancy rates were not different. In all couples where an abortion occurred, mainly parental autosomal aberrations were involved (six out of eight). Our retrospective analysis shows that an unexpectedly high number of infertile couples in an ICSI programme are affected by chromosome aberrations, which in turn may explain the reduced fertilization rates observed in this subgroup of patients.

Abortion, Spontaneous↗
PubMed1997

Combined cytogenetic and Y chromosome microdeletion screening in males undergoing intracytoplasmic sperm injection.

We evaluated the frequency of chromosomal aberrations and microdeletions of the Y chromosome in a sample of 204 patients included in an intracytoplasmic sperm injection (ICSI) programme. The prevalence of Y chromosome deletions in males with severely or only moderately reduced sparm counts is mainly unknown, so that patients were chosen with sperm counts ranging from mild oligozoospermia to azoospermia. While six out of 158 (3.8%) patients showed constitutional chromosomal aberrations, only two out of 204 (0.98%) patients were diagnosed with a microdeletion of Yq11. One had a terminal deletion in subinterval 6 of Yq11.23 which included the DAZ gene and a corresponding sperm count < 0.1 x 10(6) spermatozoa/ml. The second patient had an isolated deletion of marker Y6PH54c, a more proximal site in subinterval 5 on Yq11.23, but repeatedly showed sperm counts of 3-8 x 10(8) spermatozoa/ml. Thus, of the 158 patients who underwent a combined cytogenetic and Y-microdeletion screening, eight patients (5.1%) showed chromosomal abnormalities, either at the cytogenatic (n = 6) or the molecular level (n = 2). In conclusion, although rare in number, microdeletions of the Y chromosome can also be observed in patients with moderately reduced sperm counts. A more proximal site of the deletion breakpoint does not necessarily imply a more severe impairment of spermatogenesis than a distal deletion site. In our sample, the overall frequency of constitutional chromosomal aberrations exceeded the incidence of microdeletions of the Y chromosome even in patients with idiopathic azoo- or severe oligozoospermia.

Chromosome Deletion↗
PubMed1997

Partial trisomy 6p from a de novo translocation (6;18) with variable mosaicism in different tissues.

Partial trisomy 6p is regarded as a distinct phenotype with short stature, failure to thrive, facial dysmorphisms with blepharophimosis, mental retardation and other malformations. An 18-month-old girl with typical features of partial trisomy 6p showed a de novo unbalanced translocation resulting in partial trisomy 6p21 to pter and partial monosomy 18p11 to pter. The translocation was observed in all fibroblasts analyzed, but only in 6% of the peripheral lymphocytes.

Abnormalities, Multiple↗
PubMed1996

A new possible parameter for the detection of aneuploidy inducing substances: the analysis of qualitative and quantitative abnormalities of the spindle apparatus.

In the present study, compared to other cytogenetic methods, we measured the number of aneuploid cells directly by analyzing anomalies of the mitotic spindle. Qualitative and quantitative abnormalities of the mitotic spindle apparatus in transformed and non-transformed cell lines in vitro were classified. We treated the different cell lines with well known aneugenic agents as Benomyl and Griseofulvin and investigated the mitotic spindle under different experimental conditions. The spindle apparatus was stained by indirect immunofluorescence and the chromatin was counterstained by fluorescent dyes. The mitotic spindle showed a great sensitivity to the aneuploidy-inducing substances used in our experiments. The spindle-disturbing effect of the tested substances was demonstrated to be dose- dependent. The morphological alterations appeared to be independent of the aneuploidy-inducing test substance used, but showed a relation to the dose and length of treatment. Thus, the analysis of the mitotic spindle may be a useful screening parameter for the detection of aneuploidy-inducing substances and further investigations will provide additional results to specific parameters.

Aneuploidy↗
PubMed1996

Molecular-cytogenetic investigations of ten term placentae in cases of prenatally diagnosed mosaicism.

Discrepant chromosome findings in the placenta and fetus are detected by additional investigations commonly after chorionic villus sampling (CVS) and occasionally after amniotic fluid cell cultures. In this paper we present the results of molecular-cytogenetic investigations (fluorescence in situ hybridization, FISH) of ten term placentae after prenatally detected mosaicism. In three cases, mosaicism was found after first-trimester CVS and in seven cases, after second-trimester amniotic fluid culture. All three results after CVS represented confined placental mosaicism (CPM). Two of the seven mosaic findings after amniocentesis were not confirmed postnatally. In the remaining five cases, general mosaicism was found. The analyses of six defined areas of the term placentae showed that it is important to investigate the placenta at multiple sites. The frequency of a cell line varied by more than 50 per cent at different analysed sites. FISH on interphase nuclei proved to be a rapid and reliable method of investigating large numbers of biopsies and cells per biopsy.

Amniocentesis↗
PubMed1996

Trisomy of human chromosome 18: molecular studies on parental origin and cell stage of nondisjunction.

We investigated the parent and cell division of origin of the extra chromosome 18 in 62 aneuploids with a free trisomy 18 by using chromosome-18-specific pericentromeric short-sequence repeats. In 46 cases, DNA of patients was recovered from archival specimens, such as paraffin-embedded tissues and fixed chromosomal spreads. In 56 families, the supernumerary chromosome was maternal in origin; in six families, it was paternal. Among the 56 maternally derived aneuploids, we could exclude a postzygotic mitotic error in 52 cases. Among those in which the nondisjunction was attributable to an error at meiosis, 11 were the result of a meiosis I nondisjunction and 17 were caused by a meiosis II error. This result differs markedly from findings in acrocentric chromosomes where nondisjunction at maternal meiosis I predominates. Among the six paternally derived cases, two originated from a meiotic error, indicating that a nondisjunction in paternal meiosis is not as rare as previously suggested.

Adult↗
PubMed1996

Tetrasomy 18p de novo: identification by FISH with conventional and microdissection probes and analysis of parental origin and formation by short sequence repeat typing.

We report a de novo supernumerary isochromosome 18p in a child with tetrasomy 18p, analyzed by a straightforward combination of cytogenetic and molecular cytogenetic methods. The diagnostic procedure consisted of standard banding techniques and fluorescence in situ hybridization (FISH) with centromere and library DNA probes for chromosome 18, and 18p-specific FISH probes prepared by chromosome dissesction and in vitro amplification. The maternal origin as well as the most probable cell stages of formation of the supernumerary isochromosome were determined by typing of short sequence repeats (SSRs). The pattern of allelic distribution suggests a nondisjunction during meiosis followed by a centromeric misdivision in an early postzygotic mitosis as the most probable mode of isochromosome 18p formation. The combination of the applied methods represents a powerful tool to investigate the nature and the origin of de novo marker chromosomes.

Alleles↗
PubMed1996

Familial translocations involving 15q11-q13 can give rise to interstitial deletions causing Prader-Willi or Angelman syndrome.

A de novo interstitial deletion of 15q11-q13 is the major cause of Prader-Willi syndrome (PWS) and Angelman syndrome (AS). Here we describe two unrelated PWS patients with a typical deletion, whose fathers have a balanced translocation involving the PWS/AS region. Microsatellite data suggest that the deletion is the result of an unequal crossover between the derivative chromosome 15 and the normal chromosome 15. We conclude that familial translocations involving 15q11-q13 can give rise to interstitial deletions causing PWS or AS and that prenatal diagnosis in such families should include fluorescence in situ hybridisation or microsatellite studies or both.

Angelman Syndrome↗
PubMed1996

Further arguments for non-fortuitous association of Potter sequence with XYY males.

Although large studies on sex chromosome abnormalities have not detected a higher incidence of malformations in 47,XYY males, several case reports suggest that there is an association between renal agenesis or cystic dysplasia of the kidney and XYY status. The authors report 3 further infants with XYY karyotype who had urogenital malformations leading to Potter sequence. On the basis of our observations and review of the literature, we suggest that the XYY syndrome and Potter sequence are more significantly associated than expected by pure coincidence.

Abnormalities, Multiple↗
PubMed1994

Delineation of marker chromosomes by reverse chromosome painting using only a small number of DOP-PCR amplified microdissected chromosomes.

A new procedure for determining the chromosomal origin of marker chromosomes has been carried out. The origin of marker chromosomes that were unidentifiable by standard banding techniques could be verified by reverse chromosome painting. This technique includes microdissection, followed by in vitro DNA amplification and fluorescence in situ hybridization (FISH). A number of marker chromosomes prepared from unbanded and from GTG-banded lymphocyte chromosomes were collected with microneedles and transferred to a collection drop. The chromosomal material was amplified by a degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR). The resulting PCR products were labelled by nick-translation with biotin-11-dUTP and used as probes for FISH. They were hybridized onto normal metaphase spreads in order to determine the precise regional chromosomal origin of the markers. Following this approach, we tested 2-14 marker chromosomes in order to determine how many are necessary for reverse chromosome painting. As few as two marker chromosomes provided sufficient material to paint the appropriate chromosome of origin, regardless of whether the marker contained heterochromatic or mainly euchromatic material. With this method, it was possible to identify two marker chromosomes of a healthy proband [karyotype: 48,XY,+mar1,+mar2] and an aberrant Y chromosome of a mentally retarded boy [karyotype: 46,X, der(Y)].

Adult↗
PubMed1993

Retrospective study of the parental origin of the extra chromosome in trisomy 18 (Edwards syndrome).

The parental origin of the extra chromosome in trisomy 18 was traced in 30 informative families using highly polymorphic (CA) repeats mapped on the long arm of chromosome 18. Proband DNA was recovered from slides of chromosome preparations in 28 cases and from paraffin-embedded tissues in two cases. The extra chromosome was found to be of maternal origin in 26 cases (86.7%), and paternal origin in 4 cases (13.3%).

Adult↗