Genetic heterogeneity

Genetic heterogeneity refers to different genetic causes for the same disease and can be classified into three types: allelic heterogeneity, locus heterogeneity, and phenotypic heterogeneity. Allelic heterogeneity occurs when different mutations within the same gene lead to the same disease. For example, multiple mutations in the CFTR gene cause cystic fibrosis. Locus heterogeneity arises when mutations in different genes cause the same disorder. In retinitis pigmentosa, mutations in several genes, like RHO and PRPF31, can all lead to the same disease. Lastly, phenotypic heterogeneity refers to the variation in disease expression, where individuals with the same genetic mutation may present with different clinical symptoms or severities. An example is Marfan syndrome, where mutations in the FBN1 gene result in a wide range of manifestations, from mild to severe. These variations highlight the complexity of genetic diseases and affect diagnosis and treatment..