Genetics : heterogeneity and epigenetics

Allelic Heterogeneity:

Different mutations occurring within the same gene can lead to a similar disorder. For example, various mutations in one gene might all cause the same enzyme deficiency.

Clinical/Phenotypic Heterogeneity:

The same gene mutation can result in different diseases or a wide range of symptoms among different individuals. This means one gene can cause multiple, sometimes very different, clinical outcomes.

Unequal Expression of Alleles:

In some cases, the two alleles of a gene are not expressed equally. One allele might be more active than the other, influencing the overall phenotype.

Central Dogma:

The flow of genetic information follows the path: DNA —>RNA —>Proteins. This means that DNA is transcribed into RNA, and RNA is then translated into proteins, which perform most of the cell functions.

Exons

Exons:

These are the coding regions of a gene that are spliced together to form the final messenger RNA (mRNA) used for protein synthesis.

Introns:

Non-coding regions interspersed between exons. They are removed during RNA processing before translation.

Promoters:

DNA sequences located at the beginning of a gene. They serve as binding sites for RNA polymerase and other transcription factors, initiating transcription.

Enhancers:

Regulatory DNA elements that increase the transcription of a gene, often acting from a distance. They help boost gene expression when needed.

Silencers:

DNA elements that decrease or repress the transcription of a gene, ensuring that genes are not expressed inappropriately.