Core Genetics & Mechanisms

Point Mutation

A single-nucleotide change in a DNA sequence that can modify how a gene is expressed or how its protein product functions. Even a one-base change can dramatically alter phenotype, making point mutations crucial to understanding genetic disease, evolution, and therapeutic intervention.

Overview

Despite their small scale, point mutations are among the most powerful tools in genetics and biomedical research. They occur when one nucleotide—adenine (A), cytosine (C), guanine (G), or thymine (T)—is substituted, inserted, or deleted within a DNA sequence. Such changes can have minimal impact (as in silent mutations) or severe consequences, such as loss of gene function, altered protein structure, or disease initiation.

Types of Point Mutations

Point mutations include substitution mutations (silent, missense, nonsense), insertion and deletion (indel) mutations that can cause frameshifts, and regulatory mutations in promoters, enhancers, or splice sites that affect gene expression without changing the protein sequence.

Functional Consequences

Point mutations can cause loss-of-function (reduced or abolished protein activity), gain-of-function (new or enhanced activity), dominant-negative effects (mutant interferes with wild-type), or conditional effects that manifest only under certain conditions.

Research Applications

Point mutation mouse models are vital for disease modeling, protein function analysis, regulatory element studies, therapeutic development and validation, and precision medicine/pharmacogenomics research.

Frequently Asked Questions

How does a point mutation differ from a larger genetic alteration?

A point mutation alters only one nucleotide, whereas larger alterations involve substantial DNA insertions, deletions, or rearrangements. Despite their small size, point mutations can produce dramatic biological effects.

Are all point mutations harmful?

No. Many point mutations are neutral or silent, having no observable effect. Others can be beneficial, deleterious, or context-dependent depending on the gene, location, and environmental conditions.

Related Services

Point Mutation Mouse Models Knockin Mouse Models Conditional Knockout Mouse Models

Related Terms

Missense and Nonsense Mutations

Missense mutations change a single nucleotide in a coding region, resulting in a different amino acid in the protein sequence. Nonsense mutations convert a codon into a premature stop signal, producing truncated and often nonfunctional proteins.

Frameshift Mutation

A genetic alteration caused by the insertion or deletion of nucleotides that shifts the reading frame of a gene's coding sequence. This shift changes the downstream amino acid sequence and often introduces premature stop codons, resulting in truncated or nonfunctional proteins.

Gain-of-Function vs. Loss-of-Function Mutations

A gain-of-function mutation increases or creates a new activity for a gene or protein, while a loss-of-function mutation reduces or abolishes normal function. Both mutation types play central roles in disease biology and are critical tools in genetic research.

Knockin (KI) Mouse Models

A genetically engineered mouse in which a specific DNA sequence—such as a gene, cDNA, mutation, reporter, or human ortholog—is inserted into a defined genomic locus to add or modify gene function.

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Open Reading Frame (ORF)View All Terms Promoter / Enhancer / Regulatory Element

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