The Application of Genetic Tests in an Assisted Reproduction Unit: Sperm FISH
Nicolás Garrido, Rocio Rivera in A Practical Guide to Sperm Analysis, 2017
Intracytoplasmic sperm injection (ICSI) allows overcoming the natural barrier offered by the oocyte to sperm fertilization in couples with severe male factor infertility. Sperm fluorescence in situ hybridization (FISH) uses fluorescence DNA probes directed to specific DNA sequences in the interphase sperm nuclei. Visualizing the hybridization signals using fluorescence microscopy, it is possible to identify numerical chromosome abnormalities in the nucleus of ejaculated, epididymal, and testicular sperm. Sperm FISH analyses corroborate previous reports with altered meiosis in infertile men, as they have shown higher aneuploidy rates for chromosome 21 and sex chromosomes due to meiotic nondisjunction. Sperm heads have a tightly compacted nucleus due to the presence of disulfide bridges between protamines; this condensation of nuclear chromatin makes it inaccessible to DNA probes. Double-strand DNA denaturation of the sperm and FISH probes is carried out after incubation at high temperature. The hybridization signals are visualized using a fluorescent microscope equipped with specific filters for each fluorochrome.
Diseases of the Nervous System
George Feuer, Felix A. de la Iglesia in Molecular Biochemistry of Human Disease, 2020
The nervous system shows many more specialized features compared to any other organ. This elaborate system contains complicated anatomical and functional structures and exhibits several unique metabolic processes. The signs of disorder in neurological functions also show variations according to the anatomic level of the nervous system involved. The incidence of Down’s disease is influenced by environmental and genetic factors which increase the occurence of nondisjunction and trisomy. The study of narcosis and excitation provides an initial tool when we evaluate various disease processes of the nervous system. Excitation in the central nervous system is associated with events leading to the firing of the neurons and generation of action potentials. Lesions of the nerves are associated with characteristic degenerative changes of injured nerve cells. These changes are primary or secondary, depending on the initial integrity of the axon and its interaction with the myelin sheath and the Schwann cell.
Anomalies of Chromosomal Number: II
Murray Brookes, Anthony Zietman in Clinical Embryology, 1998
TRISOM Y 21 Down's syndrome is the commonest viable autosomal trisomy (Figure 1). The incidence increases from 1 per 1000 live births in mothers under 30 years, to 1 in 30 live births in those aged 45 years. Mothers who have had one affected child are at increased risk of having a sec ond, implying a predisposition to nondisjunction in meiosis I. Approximately 30% of the mentally handi capped people in Britain suffer from Downs syndrome.
Tetrasomy 18p in a Twin Pregnancy with Diverse Expression in Both Fetuses
Published in Fetal and Pediatric Pathology, 2016
Cihan Inan, N. Cenk Sayın, Emine Atlı, Selma Ulusal, Selen Erzincan, Isil Uzun, Hakan Gurkan, Füsun G. Varol
Tetrasomy 18p, characterized by the presence of four copies of the short arm of chromosome 18, is considered to occur with the nondisjunction in meiosis II after the errors in the meiotic and early postmeiotic mitotic division in the centromere. It is accompanied by various abnormalities including congenital heart defects, lower extremity abnormalities, micrognathia, high arched palate, kyphoscoliosis, microcephaly, myelomeningocele, hernia and renal anomalies. We present the first case of a dichorionic diamniotic twin pregnancy in which both fetuses were affected by tetrasomy 18p, but with discordant morphology, detected in one twin in the first but in the other in the second trimester.
A case of 48,XXYY syndrome detected prenatally by QF-PCR
Published in The Journal of Maternal-Fetal & Neonatal Medicine, 2009
We report on the prenatal diagnosis and genetic analysis of a 48,XXYY fetus. A 28-year-old woman was referred for amniocentesis at 18 weeks' gestation because of advanced paternal age. Quantitative-fluorescence polymerase chain reaction (QF-PCR) with small tandem repeat (STR) markers rapidly detected the sex chromosome polysomy from amniotic fluid cells. This abnormality appeared to arise from successive non-disjunction during paternal meiosis I and meiosis II. Cytogenetic analysis revealed a karyotype of 48,XXYY. This case adds to the evidence that an age-related increase in sex chromosomal aneuploidies occurs in sperm. This case also shows that QF-PCR assays can provide rapid prenatal diagnosis of numerical sex chromosome aneuploidy.
Construction of Mouse Chromosome-specific DNA Libraries and Their Use for the Detection of X-ray-induced Aberrations
Published in International Journal of Radiation Biology, 1994
J.J.W.A. Boei, A.S. Balajee, P. De Boer, W. Rens, J.A. Aten, L.H.F. Mullenders, A.T. Natarajan
We describe here the development of mouse chromosome-specific DNA libraries and their use in the detection of radiation-induced chromosome aberrations by fluorescence in situ hybridization. Large metacentric chromosomes, resulting from a translocation involving chromosomes 1, 11 and 13, were flow-sorted. Using a slit-scan technique for morphometric analysis, metacentric chromosomes were separated from normal acrocentric chromosomes and their aggregates. DNA from the metacentric chromosomes was amplified by PCR using the linker/adaptor method. In this pilot study, mouse was whole-body irradiated with 1, 2 and 3 Gy and aberrations were scored in metaphase spreads of splenocytes cultured in vitro. The results indicate that directly after radiation exposure, stable and unstable aberrations are induced at about equal frequencies in the splenocytes. The availability of chromosome-specific probes for mouse may prove very useful when analysing the behaviour of stable aberrations, as well as the testing of many suspected mutagenic carcinogens and aneugens in vivo for induction of chromosomal translocations and non-disjunction, respectively.