In _____________ heterogeneity, mutations in one of two or more
different genes can cause the same disease.
What are genes?
Genes are specific nucleotide sequences in the DNA which can direct the synthesis of a particular polypeptide of a protein.
What are gene mutations?
Gene mutation is the change in expression of a gene which is caused by change in number, sequence and types of nucleotides. When gene mutation occurs due to change in a single base pair of DNA, it is known as point mutation. When mutation is due to change in more than one base pair or entire gene it is called gross mutation. Most of the gene mutations develop due to errors in DNA replication. They are, therefore, also called copy error mutation.
Genetic heterogeneity is the process of production of similar or a single phenotype which are similar biochemically, morphologically and physiologically through different mechanisms mostly mutations.
Genetic heterogeneity is generally of 2 types :
1. Allelic heterogeneity: this is the kind of heterogeneity in which different alleles of a single gene undergo mutation to develop a particular phenotype. Example - Cystic fibrosis in which there are more than 2000 mutations in the alleles of the CFTR gene.
2. Loci heterogeneity: in this kind of heterogeneity, two or more genes which are present on different loci, undergo mutation to develop a particular phenotype and lead to a disease. Example - Alzheimer's disease in which three different genes undergo mutation to develop the disease.
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