PGD for X-linked and gender-dependent disorders using a robust, flexible single-tube PCR protocol

Area of Science:

• Genetics
• Molecular Biology
• Reproductive Medicine

Background:

• X-linked genetic disorders, such as Duchenne muscular dystrophy, can exhibit gender-specific severity.
• Prenatal diagnosis and termination are traditional prevention methods, but preimplantation genetic diagnosis (PGD) offers an alternative to avoid pregnancy termination.
• Distinguishing unaffected male embryos from affected ones is crucial in PGD for certain genetic conditions.

Purpose of the Study:

• To develop and validate a flexible multiplex fluorescence polymerase chain reaction (PCR) protocol for accurate single-cell gender determination.
• To establish a reliable method for PGD that can incorporate disease-specific genetic markers.
• To demonstrate the assay's utility in clinical PGD cycles for gender-influenced genetic diseases.

Main Methods:

• Standardization of a multiplex fluorescence PCR protocol using nine loci (four Y-chromosome, two X-chromosome, and three microsatellite markers) for single-cell analysis.
• Validation of the protocol on single lymphocytes, assessing PCR efficiency and allele dropout rates.
• Application of the assay in clinical PGD cycles for conditions like lipoid congenital adrenal hyperplasia and Duchenne muscular dystrophy.

Main Results:

• The developed PCR protocol achieved high efficiency (>93%) for all loci with minimal allele dropout rates (≤4%).
• Microsatellite analysis confirmed the absence of external contamination and validated biallelic inheritance.
• The assay successfully demonstrated its simplicity and flexibility in clinical PGD applications for gender-specific genetic disorders.

Conclusions:

• The validated multiplex fluorescence PCR assay provides a robust and flexible tool for single-cell gender determination in PGD.
• This method enhances the accuracy of PGD for X-linked and gender-influenced genetic diseases, improving embryo selection.
• The protocol's adaptability allows for the integration of disease-specific loci, offering a comprehensive approach to genetic screening in PGD.