2020–2021 BCSC Basic and Clinical Science Course™
2 Fundamentals and Principles of Ophthalmology
Part III: Genetics
Chapter 5: Molecular Genetics
Cell division occurs via a complex process known as the cell cycle. The function of tumor suppressor genes is to regulate this cycle. Mutations to these genes result in numerous conditions with ophthalmic manifestations, examples of which are neurocutaneous disorders (phakomatoses) and retinoblastoma.
Approximately 95% of DNA does not code for proteins and may be involved in regulation of gene expression. The term epigenetics refers to the study of heritable processes that alter gene expression without changing the DNA sequence.
Transcription factors determine the rate of messenger RNA production from DNA. The family of PAX genes encodes for transcription factors, mutations of which are involved in the development of numerous ophthalmic conditions.
Alternate splicing allows different isoforms of a particular protein to be expressed. Vascular endothelial growth factor and its receptors have various isoforms due to this mechanism.
Mitochondrial DNA (mtDNA) is passed on to children from their mothers. Many diseases with ophthalmic manifestations occur because of mutations in mtDNA, including chronic progressive external ophthalmoplegia and Leber hereditary optic neuropathy.
New gene therapies such as AAV (adeno-associated virus) vector gene therapy and the CRISPR-Cas9 system have the potential to treat many previously untreatable eye diseases.
Excerpted from BCSC 2020-2021 series: Section 2 - Fundamentals and Principles of Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.