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Single-cell analysis of unstable genes
R Daniels1, C Holding, E Kontogianni
1Molecular Embryology Unit, Institute of Child Health, London, UK.
Journal of Assisted Reproduction and Genetics
|February 1, 1996
Summary
Sensitive diagnostic procedures for myotonic dystrophy and fragile X triplet repeat genes were developed for single cells. These methods enable early detection of gene expansion and transcription in human embryos.
Area of Science:
- Genetics
- Molecular Biology
- Reproductive Medicine
Background:
- Myotonic dystrophy and fragile X are genetic disorders caused by triplet repeat expansions.
- Accurate diagnosis and understanding of repeat expansion timing are crucial for genetic counseling and treatment.
Purpose of the Study:
- To develop sensitive diagnostic assays for triplet repeat genes (myotonic dystrophy, fragile X) in single human cells.
- To investigate the feasibility of single-cell analysis for preimplantation genetic diagnosis of triplet repeat diseases.
Main Methods:
- Refinement of polymerase chain reaction (PCR) assays for single-cell sensitivity.
- Development of 'Repeat Primer PCR' for detecting fragile X expansions in buccal cells.
- Single-cell reverse transcriptase PCR for monitoring gene transcription in embryos.
Main Results:
- Sensitive PCR assays established for normal alleles of myotonic dystrophy and fragile X genes.
- A novel PCR method developed to detect full fragile X expansions.
- Demonstrated detection of myotonic dystrophy gene transcription from the paternal allele in 1-cell stage human embryos.
Conclusions:
- Developed sensitive diagnostic procedures for triplet repeat genes in single cells, advancing preimplantation genetic diagnosis.
- Identified challenges like in vitro expansion and allele drop-out for myotonic dystrophy stability studies.
- New PCR procedure for fragile X expansions aids in monitoring early embryonic development and repeat expansion timing.