Intron

How it is used

Used in gene structure, splicing and clinical genetics. Introns are numbered like exons ('intron 4'). Variants deep inside an intron are often harmless, but changes near the exon–intron boundary can disrupt splicing. In most human genes, introns are much longer than exons.

Example sentences

1. The variant lies two bases into intron 6 and is predicted to affect splicing.

2. Most bacterial genes have no introns, so we can express them directly from genomic DNA.

Common collocations

• intron retention
• intronic variant
• exon–intron boundary
• splice site

Related terms

• exonA part of a gene that stays in the mature mRNA after splicing; most exons contain sequence that codes for the protein.
• mRNAMessenger RNA: the RNA copy of a gene that carries its instructions from the DNA in the nucleus to the ribosomes, where the protein is made.
• transcriptionThe first step of gene expression, in which an enzyme called RNA polymerase copies the DNA sequence of a gene into a matching RNA molecule.
• geneA section of DNA that carries the instructions for making a protein or a functional RNA molecule; it is the basic unit of heredity passed from parents to children.

More terms: Gene Expression and Regulation

• gene expression
• translation
• promoter
• codon
• transcription factor
• epigenetics
• upregulate