hypomorphic mutation
Pronunciation: high-poh-MORF-ik
A genetic mutation that reduces but does not eliminate protein function, often causing milder immunodeficiency phenotypes.
Full Definition
A hypomorphic mutation is a genetic alteration that partially impairs gene function, resulting in reduced but not completely absent protein activity. In pediatric immunology, hypomorphic mutations often cause atypical or milder presentations of primary immunodeficiencies compared to null mutations. These mutations may lead to delayed onset of symptoms, partial immune dysfunction, or phenotypes that don't fit classic disease descriptions. Patients with hypomorphic mutations may retain some immune function, making diagnosis more challenging.
Usage
Usage note: Contrast with null mutations (complete loss of function) and gain-of-function mutations.
In Context
- "The hypomorphic mutation explained the patient's atypical SCID presentation with partial T-cell function." — Genetic counseling report
- "Hypomorphic mutations in RAG1 can cause delayed-onset combined immunodeficiency rather than classical SCID." — Research publication