The replacement of cytogenetic analysis by direct chorionic villi sampling preparation with quantitative fluorescence PCR.

AIM: The aim of this study is to assess the replacement of chromosomal analysis of chorionic villi (CV) direct preparation samples (DIR) by quantitative fluorescence PCR (QF-PCR) and to determine its advantages in routine prenatal diagnosis. METHODS: From a total of 4,020 CV samples, rapid results were obtained either by conventional cytogenetic analysis of DIR in 2,770 samples, or by QF-PCR analysis in 1,250 samples. The final results were given after long-term culture (LTC). RESULTS: The frequencies of unbalanced fetal karyotypes were not significantly different, being 4.8% by DIR-LTC and 4.3% by QF-PCR-LTC. No false-negative or false-positive results were obtained from either approach. CONCLUSION: QF-PCR can replace chromosomal analysis of CV-DIR in most cases during routine prenatal diagnosis, requiring smaller CV samples and being more labor effective. Coupled with LTC, it is a robust diagnostic approach with high predictive value for the most frequent fetal trisomies.

Loss of the Y chromosome PAR2 region and additional rearrangements in two familial cases of satellited Y chromosomes: cytogenetic and molecular analysis.

Two cases of rare structural aberrations of the Y chromosome were detected: a del(Y) (q12) chromosome in a child with mild dysmorphic features, obesity and psychomotor delay, and two identical satellited Y chromosomes (Yqs) in a normal twin, which were originally observed during routine prenatal diagnosis. In both cases a Yqs chromosome was detected in the father which had arisen from a reciprocal translocation involving the short arm of chromosome 15 and the heterochromatin of the long arm of the Y chromosome (Yqh). Cytogenetic and molecular studies demonstrated that in the reciprocal product of chromosomes 15 and Y PAR2 could not be detected, showing that PAR2 had been deleted. It is discussed whether the translocation of the short arm of an acrocentric chromosome to the heterochromatin of the long arm of the Y chromosome causes instability of this region which results either in loss of genetic material or interference with the normal mechanism of disjunction.

Rare XXY/XX mosaicism in a phenotypic male with Klinefelter syndrome: case report.

Klinefelter syndrome represents the most commonly found human sex chromosomal abnormality. It is characterized by small, firm testes with hyalinization of the seminiferous tubules, elevated gonadotropins and azoospermia. Males with Klinefelter syndrome may have a 47,XXY or a mosaic 47,XXY/46,XY constitutional karyotype and varying degrees of spermatogenic failure. Mosaicism 47,XXY/46,XX with clinical features suggestive of Klinefelter syndrome, is very rare and so far only 10 cases have been described in literature [1,2,5,8,10,15,22,23,25,44]. We report here a case of a mosaic 47,XXY/46,XX infertile male in whom detailed cytogenetic, histological and molecular studies were performed. Cytogenetic analysis revealed 80% and 50% mosaicism for the 46,XX cell line in blood lymphocytes and in skin fibroblasts, respectively, and the presence of 47,XXY cells only, in cultured testicular tissue. Testicular histopathology revealed atrophy of the testes with no spermatogenesis and absence of germ cells. Molecular analysis showed paternal inheritance of the extra X chromosome.

A prenatally ascertained, maternally inherited 14.8 Mb duplication of chromosomal bands Xq13.2-q21.31 associated with multiple congenital abnormalities in a male fetus.

Duplications of the X chromosome are rare cytogenetic findings, and have been associated with an abnormal phenotype in the male offspring of apparently normal or near normal female carriers. We report on the prenatal diagnosis of a duplication on the long arm of chromosome X from chromosomal band Xq13.2 to q21.31 in a male fetus with increased nuchal translucency in the first trimester and polyhydramnios at 22 weeks of gestation. Amniocentesis was undertaken and cytogenetic analysis revealed additional chromosomal material in the long arm of chromosome X at position Xq13. Analysis with high resolution array CGH revealed the additional material is in fact a duplication of the region Xq13.2-q21.13. The duplication is 14.8 Mb in size and includes fourteen genes: SLC16A2, KIAA2022, ABCB7, ZDHHC15, ATRX, MAGT1, ATP7A, PGK1, TBX22, BRWD3, POU3F4, ZNF711, POF1B and CHM. Analysis of the parents revealed the mother to be a carrier of the same duplication. After elected termination of the pregnancy at 28 weeks a detailed autopsy of the fetus allowed for genotype-phenotype correlations.

Prenatal diagnosis of two rare de novo structural aberrations of the Y chromosome: cytogenetic and molecular analysis.

Two rare de novo structural aberrations of the Y chromosome were detected during routine prenatal diagnosis: a satellited non-fluorescent Y chromosome (Yqs), the first de novo Yqs to be reported in a fetus, and a terminal deletion of the Y chromosome long arm del(Y)(q11). In both cases detailed cytogenetic and molecular analyses were undertaken. In the case of the Yqs it was demonstrated by fluorescence in situ hybridization (FISH) that the satellites were derived from chromosome 15. In the case of the del(Yq), it was shown with molecular analysis by polymerase chain reaction (PCR) amplification of sequence-tagged sites (STS-PCR) that the deleted portion of the long arm of chromosome Y included the azoospermia factor loci, AZFb and AZFc. The clinical significance of these findings is discussed.