Islands of linkage disequilibrium

To determine whether traits are inherited together or separately, Gregor Mendel crossed pea plants that differed in two traits. These parental plants were homozygous for both traits but displayed different phenotypes. The first generation of offspring were all dihybrids, heterozygotes exhibiting the two dominant phenotypes. When self-fertilized, the dihybrids consistently produced progeny with a 9:3:3:1 ratio of four possible phenotype combinations. This ratio suggested that inheriting one...

Natural selection—probably the most well-known evolutionary mechanism—increases the prevalence of traits that enhance survival and reproduction. However, evolution does not merely propagate favorable traits, nor does it always benefit populations.Life is not fair. A deer grazing contentedly in a field can have her meal cut tragically short by a bolt of lightning. If the doomed doe is one of only three in the population, 1/3 of the population’s gene pool is lost. Random events like this can...

To determine whether traits are inherited together or separately, Gregor Mendel crossed pea plants that differed in two traits. These parental plants were homozygous for both traits but displayed different phenotypes. The first generation of offspring were all dihybrids, heterozygotes exhibiting the two dominant phenotypes. When self-fertilized, the dihybrids consistently produced progeny with a 9:3:3:1 ratio of four possible phenotype combinations. This ratio suggested that inheriting one...

Like autosomes, sex chromosomes contain a variety of genes necessary for normal body function. When a mutation in one of these genes results in biological deficits, the disorder is considered sex-linked.Y chromosome mutations are called “Y-linked” and only affect males since they alone carry a copy of that chromosome. Mutations to the relatively small Y chromosome can impact male sexual function and secondary sex characteristics. Y-chromosome infertility is a disorder that affects sperm...

The seminal work of Ohno in 1970 popularized the idea of gene duplication and divergence. DNA sequence comparison studies reveal that a large portion of the genes in bacteria, archaebacteria, and eukaryotes was  generated by gene duplication and divergence, indicating its critical role in evolution.
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.

Genome-wide association studies or GWAS are used to identify whether common SNPs are associated with certain diseases. Suppose specific SNPs are more frequently observed in individuals with a particular disease than those without the disease. In that case, those SNPs are said to be associated with the disease. Chi-square analysis is performed to check the probability of the allele likely to be associated with the disease.
GWAS does not require the identification of the target gene involved in...