Regine Schubert

Genetic Counseling in a Patient with XXY/XXXY/XY Mosaic Klinefelter’s Syndrome: Estimate of Sex Chromosome Aberrations in Sperm Before Intracytoplasmic Sperm Injection

Abstract Objective: To report the sex chromosome aberrations in the sperm of a patient with mosaic Klinefelters syndrome before ICSI. Design: Case report. Setting: Institute of Human Genetics, University Hospital Patient(s): A patient with an XXY/XXXY/XY mosaic Klinefelters syndrome and extreme oligozoospermia. Intervention(s): Skin biopsy, buccal smear, hair root sampling, and semen sampling. Main Outcome Measure(s): The karyotypes of three additional somatic cell systems and the ratio of sex chromosome aberrations in sperm. Result(s): After two-color fluorescence in situ hybridization of 202 interphase sperm nuclei, both the proportion of hyperhaploid 24,XY and 25,XXY sperm (5.0% and 0.5%, respectively) and of hyperhaploid 24,XX sperm (2.0%) were elevated. In contrast with peripheral lymphocytes, 93.9% of which showed sex chromosome aberrations, in the present patient only 7.5% of sperm proved to be hyperhaploid with an extra sex chromosome. Conclusion(s): The determination of sex chromosome aberrations in the sperm of a patient with mosaic Klinefelters syndrome may provide additional information to estimate the transmission risk to his offspring.

Supernumerary marker chromosomes derived from chromosome 15: analysis of 32 new cases

Small supernumerary marker chromosomes (SMC) are a heterogeneous group of chromosomes with an estimated frequency of approximately 0.14–0.72 per 1000 newborns and higher frequencies in particular populations such as the mentally retarded or infertile males. With a frequency of about 50%, derivatives of chromosome 15 represent the most common SMC. Here we present the results of a detailed analysis of 32 SMC(15) carriers who were ascertained in pre‐ or post‐natal routine cytogenetic diagnostics. SMC(15) with euchromatic content led to mental and psychomotor retardation. In contrast, SMC(15) without euchromatin were found to have no influence on the carriers phenotype but were detected with a high incidence among infertile males. The majority of SMC(15) are pseudodicentric homologous rearrangements. Based on our investigations a further characterization of der(15) was possible.

Characterisation, phenotypic manifestations and X-inactivation pattern in 14 patients with X-autosome translocations

Here we describe a group of 14 patients carrying different X‐autosome translocations and exhibiting phenotypes that demonstrate the range of alterations induced by such aberrations.All male carriers of an X‐autosome translocation in our investigation group were infertile, whereas fertility in the female carriers was dependent on the position of the break‐point in the X chromosome. Fertile women with translocation break‐points outside of the critical region (Xq13‐q26) in some cases passed on the translocation to their offspring. In balanced female carriers in our group, the normal X chromosome was usually inactivated, allowing full expression of genes on the translocated segments. In one case, disruption of the dystrophine gene in Xp21 led to the manifestation of Duchenne muscular dystrophy in a female carrier. Inactivation of the derivative X (Xt) in a balanced female carrier led to a partial monosomy of the autosome/disomy of the X chromosome and resulted in an aberrant phenotype. In unbalanced carriers, Xt is generally late‐replicating/inactive, although failed spreading of inactivation to the autosomal segment often results in a partial trisomy, as evidenced by the case of an unbalanced translocation carrier in our group.

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.

Analysis of a de novo complex chromosome rearrangement involving chromosomes 4, 11, 12 and 13 and eight breakpoints by conventional cytogenetic, fluorescence in situ hybridization and spectral karyotyping

A complex chromosome rearrangement (CCR) with eight breakpoints resulting in four derivative chromosomes (4, 11, 12 and 13) was detected prenatally in a male fetus of a twin pregnancy. The karyotype of the female second fetus was normal. The apparently balanced de novo CCR was identified by classical cytogenetic methods and fluorescence in situ hybridization (FISH). We compared these findings with results from spectral karyotyping (SKY). Copyright

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.

Ring Chromosome 18: Clinical, Cytogenetic and Molecular Genetic Studies on Four Patients

Abstract Ring chromosomes are a rare chromosomal aberration but have meanwhile been reported for nearly all human chromosomes. We describe four de novo carriers (1 boy and 3 girls) of ring chromosome 18 (r(18)): while three patients had a non-mosaic 46,r(18) karyotype, the fourth was a mosaic: mos 46,XX, r(18)/46,XX, der(18). Phenotypically, the boy showed only minor anomalies, but the female probands presented several clinical features, among them microcephaly, a moderate to severe muscular hypotonia, psychomotoric retardation and short stature. Major malformations were heart defects, cleft lip and palate and atresia of the external auditory canal. In one girl with very short stature, we found a hypothalamic growth hormone deficiency. By investigating the children over 2,5 years it could be demonstrated that the ring chromosomes were passed regularly through mitosis. The parental origin of the ring was determined in three cases indicating a postzygotic mitotic error.

Characterization of the Karyotype in Patients with Multiple Myeloma by the Combination of Karyotype Analysis, FISH and CGH

Abstract Cytogenetic and molecular cytogenetic investigations from bone marrow samples were performed in 83 patients with multiple myeloma. Karyotype analyses were made after cultivation with and without growth factors. The polyploidy level ranged from 3n to 6n. For each patient the composite karyotype was delineated. The number of abnormalities per aberrant cell was in a range from 1 to 17 (x =3,7). The comparison of CGH and FISH results showed an accordance of 92%. In total, 57% of cells showed chromosomal aberrations.

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.