intronic

Intronic is an adjective describing features related to introns, the noncoding segments of genes found in most eukaryotes. Introns are transcribed into precursor messenger RNA but are removed during RNA processing, so they are not present in the mature transcript that is translated into protein. Exons, in contrast, encode the amino acid sequence of a protein.

Introns vary widely in length and number across genes. They often contain regulatory elements that influence transcription and splicing, and some introns harbor noncoding RNA genes, such as microRNAs, or sequences that modulate gene expression. Through alternative splicing, introns contribute to transcript diversity by producing multiple mRNA isoforms from a single gene.

Mutations within introns can disrupt normal splicing, leading to abnormal proteins and disease. Changes that create or activate cryptic splice sites, alter branch points, or affect splicing enhancers or silencers can cause improper transcript processing. Intronic variants are a focus of genomic studies as potential contributors to inherited conditions.

Introns are common in eukaryotic genomes but are rare or absent in most prokaryotes. Some genes are intronless, while others are intron-rich, with long or numerous introns. The presence and organization of introns can influence genome size and evolutionary dynamics.

In biotechnology and research, intron sequences are sometimes used in gene constructs to enhance expression or to enable specific splicing patterns in transgenes. Intronic regions thus play a multifunctional role in gene structure, expression, and regulation.