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K Sermon

Publications and source records attributed to K Sermon.

42 records · Page 3Linked to original sources
PubMed1995

Simultaneous amplification of the two most frequent mutations of infantile Tay-Sachs disease in single blastomeres.

Tay-Sachs disease is a lysosomal storage disease, which in its most severe form leads inexorably to death during infancy. We have developed a method for preimplantation diagnosis, using polymerase chain reaction (PCR) technology, by which the two most frequent mutations occurring in this disease can be amplified simultaneously. We have tested this method on single blastomeres and have compared four lysis methods: (i) boiling in water at 94 degrees C for 15 or (ii) 30 min, and (iii) incubation in an alkaline lysis buffer for 30 min at 94 degrees C or (iv) at 65 degrees C for 10 min. The amplification percentages were 21, 67, 71 and 91% respectively.

Base Sequence↗
PubMed1992

Preimplantation diagnosis.

Although healthy babies have been born after preimplantation diagnosis for sex determination, this technique is still in an experimental phase. To date, removal by micromanipulation of one or two blastomeres from an eight-cell embryo seems an acceptable procedure. Since a reasonable number of biopsied embryos will implant and develop in utero, the methodology for the analysis of the blastomeres at the chromosomal, gene product or DNA level, needs to be improved before further clinical application. In the meanwhile, more information about early embryo development will become available.

Animals↗
PubMed1992

Beta-N-acetylhexosaminidase activity in human oocytes and preimplantation embryos.

beta-N-acetylhexosaminidase is a lysosomal enzyme, which has two isoenzymes: beta-Hex A, a trimer consisting of one alpha-chain and two beta-chains (alpha beta 2) and beta-Hex B, a tetramer formed of four beta-chains (beta 2 beta 2). Genetic defects in the alpha-chain lead to Tay-Sachs disease, whereas mutations in the beta-chain gene lead to Sandhoff disease. In a previous study we developed a microassay for total beta-N-acetylhexosaminidase and used this for measuring activities in mouse oocytes and preimplantation embryos. In this study, to assess the feasibility of transferring this technique to the human for the purposes of preimplantation diagnosis for Tay-Sachs and Sandhoff disease, beta-Hex activity was assayed in human oocytes and embryos and in the medium in which they had been cultured. We showed that although the activity of beta-N-acetylhexosaminidase in human oocytes and embryos was > 500 times higher than in the mouse, it was not detectable in the culture medium and the activity in oocytes and embryos remained virtually constant throughout human preimplantation development, making it difficult to distinguish embryonic from maternal enzyme activity. In the absence of this distinction it would be inappropriate to use beta-N-acetylhexosaminidase activity for the purposes of preimplantation diagnosis of Sandhoff or Tay-Sachs disease. These experiments demonstrate that measuring the beta-N-acetylhexosaminidase activity in human embryos cannot be used at present for preimplantation diagnosis.

Blastocyst↗
PubMed1991

Beta-N-acetylhexosaminidase activity in mouse oocytes and preimplantation embryos.

Beta-N-Acetylhexosaminidase is a lysosomal enzyme; mutation in this protein leads to Tay-Sachs or Sandhoff disease. We have developed an assay for the beta-N-acetylhexosaminidase in mouse oocytes and preimplantation embryos. Activity was low in oocytes and zygotes and started to rise from the late 2-cell stage. By using alpha-amanitin, an inhibitor of DNA-dependent RNA polymerase, we were able to show that the first embryonic mRNA transcriptions of the beta-N-acetylhexosaminidase genes take place between 38 and 46 h post HCG (early 2-cell stage) and between 46 and 54 h post HCG (late 2-cell stage).

Amanitins↗
PubMedDate not supplied

The Brussels' experience of more than 5 years of clinical preimplantation genetic diagnosis.

This paper describes the 5 years' experience of preimplantation genetic diagnosis (PGD) at the Brussels Free University. Our first PGD was carried out in February 1993. Up to October 1998, we carried out 183 PGD cycles on fresh cleavage embryos of 92 couples for 25 different conditions. Patients were treated for autosomal recessive (n = 39), autosomal dominant (n = 65) and X-linked recessive (n = 47) monogenic disorders as well as for autosomal structural aberrations (n = 10), sex chromosome numerical and structural aberrations (n = 21) and a combination of the two latter (n = 1). Specific diagnosis was carried out by polymerase chain reaction (n = 108). Fluorescence in-situ hybridization was used for sexing (n = 64) and structural aberrations (n = 11). We transferred 1.6 +/- 1.1 embryos per cycle, resulting in an implantation rate of 12.0% per replaced embryo. Ongoing pregnancies were achieved in 29 cycles, i.e. 23 singletons, five twins and one dichorionic triplet with an acardius acranius. The ongoing pregnancy rates per cycle, per transfer and per couple were 16.4, 19.9 and 31.5% respectively. While 28 ongoing pregnancies resulted in the births of 34 infants, one pregnancy was terminated after misdiagnosis. The results of 24 PGD were confirmed by prenatal diagnosis or after birth while no information was available in four pregnancies. Our series demonstrates that PGD is a feasible technique by which to avoid the birth of genetically affected children to couples at risk.

Adult↗