A case of prenatal detection of a de novo unbalanced complex chromosomal rearrangement involving four chromosomes.

Complex chromosomal rearrangements are rarely observed prenatally. Genetic counceling of CCR carriers is complicated, especially in cases of de novo origin of the rearrangement. Here we present a new case of a de novo CCR involving four chromosomes observed in amniotic fluid cells of the fetus at 17 weeks of gestation. The rearrangement was characterized as an apparently balanced four-way translocation t(1;11;7;13)(~p21;~q13.5;~q32;~q22)dn by conventional cytogenetic studies. However, array-based comparative genomic hybridization revealed 5 submicroscopic heterozygous interstitial deletions on chromosome 1, 11, 7, 13 with a total loss of 21.1 Mb of genetic material in regions close to those, designated as breakpoints by conventional cytogenetic analysis. The described case clearly illustrates that high-resolution molecular genetic analysis should be combined with conventional cytogenetic techniques to exclude subtle chromosomal abnormalities in CCR cases detected prenatally.

[CHROMOSOMAL ABNORMALITIES IN PATIENTS WITH INFERTILITY].

To assess the frequency and structure of chromosomal abnormalities in patients with infertility, a retrospective analysis of cytogenetic studies of 3414 patients (1741 females and 1673 males), referred to the Clinic of reproductive medicine "Nadiya" from 2007 to 2012, was performed. Chromosomal abnormalities were detected in 2.37% patients: 2.79% in males and 1.95% in females. Balanced structural chromosomal abnormalities prevailed over numerical abnormalities and corresponded to 80.2% of all chromosomal abnormalities detected in the studied group. Sex chromosome abnormalities made up 23.5% of chromosomal pathology (19/81) and included gonosomal aneuploidies in 84% of cases (16/19) and structural abnormalities of chromosome Y in 16% of cases (3/19). The low level sex chromosome mosaicism was detected with the frequency of 0.55%. Our results highlight the importance of cytogenetic studies in patients seeking infertility treatment by assisted reproductive technologies, since an abnormal finding not only provide a firm diagnosis to couples with infertility, but also influences significantly the approach to infertility treatment in such patients.

[Meiotic segregation of chromosomes 13 and 14 of heterozygous Robertsonian translocation der(13;14) (q10; q10) carriers].

Meiotic segregation of chromosomes 13 and 14 was assessed by fluorescence in situ hybridization on sperm of five heterozygous carriers of the most frequent Robertsonian translocation der(13;14). Alternate segregation mode was predominant (mean 78.2 +/- 5.7%). The prevalence of balanced sperm varied from 69.4 to 86.5%. Adjacent segregation mode was detected in 18.64 +/- 4.90% of sperm; 3:0 mode was detected in 2.48 +/- 1.20% of sperm. These results are informative for reproductive counseling of Robertsonian translocation der(13;14) carriers, providing information for assessment of probability of receiving normal/balanced embryos in assisted reproduction cycles.

[A case of deletion of the short arm of the chromosome 21 (21p-) (christchurch chromosome) discovered prenatally:clinical and cytogenetic data]. / Opisanie sluchaia deletsii korotkogo plecha khromosomy 21 (21p-) (christchurch chromosome), vyiavlennogo prenatal'no: klinicheskie i tsitogeneticheskie dannye.

Results of cytogenetic research of placental villi and amniotic fluid cells culture of the 22-weeks-old fetus with multiple congenital malformations (MCM) are presented. The absence of the short arm in one of the homologue of the chromosome 21 was revealed. Cytogenetic analysis of the fetus father's blood lymphocytes determined the similar chromosome. Further research of the father's karyotype made by FISH-method using specific DNA samples had discovered the absence of subtelomeric parts in the short arm of the chromosome 21 that might be considered as a deletion. It was suggested that the effect of position and interaction of genes could play a key role in appearing of MCM in the fetus in the case when the 21p-chromosome was transferred to it from the healthy parents.

[Molecular diagnosis of fragile X-chromosome syndrome (Martin-Bell syndrome) in patients of native populations]. / Molekuliarnaia diagnostika sindroma fragil'noi X-khromosomy (sindrom Martina-Bella) u bol'nykh otechestvennykh populiatsii.

63 families at-rist of Fragile X-syndrome (FraX) are subjected to Southern blot analysis with the DNA probes Ox1.9 and Ox0.55. Molecular studies have confirmed an initial clinical diagnosis of FraX in 26 families earlier studied cytogenetically and in 11 of 27 families with only some clinical traits of FraX syndrome in proband. Full mutation and premutation condition of FMR-1 gene was ascertained in 34 and rejected in 18 close relatives of probands with the proved FraX syndrome in 37 and families. Four different patterns of pathological alleles are detected at electrophoretograms of DNA samples restricted by endonuclease RcoRI and hybridized to the DNA probe Ox1.9. Prenatal diagnosis of FraX was carried out in two cases at the 1st and 2nd trimester of pregnancy. Perspective of broad application of molecular methods for early diagnostics and prophylactic of FraX syndrome are briefly discussed.

[Screening of mentally retarded persons for "fragile" X-chromosome]. / Skryninh rozumovo vidstalykh osib na "lamku" X-khromosomu.

112 mentally weak persons aged from 2 to 18 with different degree of oligophrenia have been examined. Cultivation of blood lymphocytes was performed on medium 199 containing 5% of cattle serum. 9 persons with "fragile" X-chromosome are revealed. High frequency of autosomes fragility among the examined contingent of patients is found. A supposition is advanced on interrelation between homozygosity of "fragile" parts of autosomes and oligophrenia.