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Prenatal interphase FISH diagnosis of PLP1 duplication associated with Pelizaeus-Merzbacher disease
1Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
Abstract:
A submicroscopic genomic duplication in Xq22.2 that contains the entire proteolipid protein 1 gene (PLP1) is responsible for the majority of Pelizaeus-Merzbacher disease (PMD) patients. We previously developed an interphase FISH assay to screen for PLP1 duplications in PMD patients using peripheral blood and lymphoblastoid cell lines. This assay has been utilized as a clinical diagnostic test in our cytogenetics laboratory. To expand usage of the interphase FISH assay to prenatal diagnosis of PLP1 duplications, we examined three PMD families with PLP1 duplications utilizing aminiotic fluid samples. In two families the FISH assay revealed fetuses with PLP1 duplications, whereas the other fetus showed a normal copy number of PLP1. Haplotype analyses, as well as an additional FISH analysis using postnatal blood samples, confirmed the results of the prenatal analyses. Our study demonstrates utility of the interphase FISH assay in the prenatal diagnosis of PLP1 duplications in PMD.
Insights
This study validates an interphase FISH assay for prenatal diagnosis of Pelizaeus-Merzbacher disease (PMD). The assay accurately detects proteolipid protein 1 gene (PLP1) duplications in amniotic fluid, aiding early detection in at-risk pregnancies.
Area of Science:
- Genetics
- Molecular Biology
- Prenatal Diagnostics
Background:
- Pelizaeus-Merzbacher disease (PMD) is primarily caused by submicroscopic genomic duplications of the proteolipid protein 1 gene (PLP1) at Xq22.2.
- An established interphase FISH assay effectively screens for PLP1 duplications in PMD patients using blood and lymphoblastoid cell lines.
- This assay is currently employed as a clinical diagnostic tool in cytogenetics laboratories.
Purpose of the Study:
- To evaluate the utility of the interphase FISH assay for the prenatal diagnosis of PLP1 duplications.
- To assess the feasibility of using amniotic fluid samples for detecting PLP1 duplications in at-risk pregnancies.
Main Methods:
- Utilized an established interphase FISH assay on amniotic fluid samples from three PMD families with known PLP1 duplications.
- Conducted haplotype analyses to confirm FISH results.
- Performed postnatal FISH analysis on blood samples for further validation.
Main Results:
- The interphase FISH assay successfully identified fetuses with PLP1 duplications in two of the three families examined.
- One fetus was determined to have a normal copy number of the PLP1 gene.
- Prenatal findings were corroborated by subsequent haplotype and postnatal FISH analyses.
Conclusions:
- The interphase FISH assay is a valuable tool for the prenatal diagnosis of PLP1 duplications.
- This assay can be reliably applied to amniotic fluid for early detection of PMD-associated genetic abnormalities.
- The study confirms the assay's utility in expanding diagnostic capabilities to prenatal settings for PMD.