Intermediate
Technical
In the Industry Vocabulary Test
loss of heterozygosity
Also written as: LOH — loss of heterozygosity
A genomic event where one allele is deleted or altered, leaving only one functional copy of a gene.
Full Definition
A chromosomal alteration in which one of two alleles at a heterozygous locus is lost through deletion, mutation, or other mechanisms, resulting in hemizygous expression. In cancer, LOH frequently affects tumor suppressor genes following Knudson's two-hit hypothesis, where the remaining allele may be inactivated by mutation. LOH analysis helps identify genomically unstable tumors and can indicate therapeutic vulnerabilities or resistance mechanisms.
Usage
Usage note: Always spell out on first use, then use LOH abbreviation; distinguish from simple copy number loss.
In Context
- "Loss of heterozygosity analysis revealed extensive chromosomal instability in the high-grade serous ovarian carcinoma." — Research manuscript
- "The tumor showed LOH at the TP53 locus, consistent with the identified frameshift mutation." — Genomic analysis report
Also known as
LOH
allelic loss
Contrasted with
heterozygosity retention
Don't confuse with
allelic imbalance
copy number loss