Heterozygous refers to having two different alleles at a particular gene locus.
Understanding Heterozygous Genotype
In genetics, individuals inherit two copies of each gene, one from each parent. These copies are called alleles. When the alleles for a specific gene are different, the individual is described as heterozygous for that gene.
Key Characteristics of Heterozygous Genotypes
- Two different alleles: The hallmark of a heterozygous genotype is the presence of two distinct alleles for a specific gene.
- Possible combinations:
- One normal allele and one mutated allele.
- Two different mutated alleles (compound heterozygote).
Example:
| Allele 1 | Allele 2 | Genotype | Description |
|---|---|---|---|
| A | a | Heterozygous | One dominant allele (A) and one recessive allele (a). |
| Mutant 1 | Mutant 2 | Compound Heterozygote | Two different mutated alleles for the same gene. |
Examples
- Cystic Fibrosis: An individual might inherit one normal allele for the CFTR gene and one mutated allele. This person is a carrier of cystic fibrosis but doesn't usually show symptoms because the normal allele can compensate for the mutated one.
- Sickle Cell Trait: Individuals with one normal hemoglobin allele and one sickle cell allele have sickle cell trait. They usually don't have sickle cell anemia but can pass the sickle cell allele to their children.
