Symptomatic presentation of a sickle cell heterozygote: an evaluation of genetic factors

For the same gene multiple alleles can interact to influence phenotypes like the shape and protein composition of an individual cells.By studying allele interactions on the molecular and cellular levels researchers can understand the resulting phenotypes and complications of human conditions like sickle cell trait, improving treatment.The ABO blood group system is a common example of multiple alleles in humans. This system includes three alleles called IA, IB, and i alleles, which combine in...

Genetic variation is the diversity in DNA sequences found among individuals of the same species. This diversity is crucial for a species' survival because it helps organisms adapt to environmental changes. Genetic variation begins with fertilization, where an egg and sperm cell merge. Each of these cells carries 23 chromosomes, up to 46 in the fertilized egg. Chromosomes are long DNA strands that contain genes, the basic units of heredity.
Genes exist in different versions called alleles, which...

An organism is diploid if it inherits two variants, or alleles, of each gene, one from each parent. These two alleles constitute the genotype for a given gene. The term genotype is also used to refer to an organism’s complete set of genes. A diploid organism with two identical alleles has a homozygous genotype, whereas two different alleles indicate a heterozygous genotype. Observable traits arising from genotypes are called phenotypes, which can also be influenced by environmental factors. An...

A pedigree is a diagram displaying a family’s history of a trait. Analyzing pedigrees can reveal (1) whether a trait is dominant or recessive, (2) the type of chromosome, autosomal or sex, a trait is linked to, (3) genotypes of family members, and (4) probabilities of phenotypes in future generations. For families with a history of autosomal or sex-linked diseases, this information can be crucial to family planning.Pedigrees Display Family HistoriesIn various plant and animal species,...

Gregor Mendel's work (1822 - 1884) was primarily focused on pea plants. Through his initial experiments, he determined that every gene in a diploid cell has two variants called alleles inherited from each parent. He suggested that amongst these two alleles, one allele is dominant in character and the other recessive. The combination of alleles determines the phenotype of a gene in an organism.

Agouti: A Lethal Allele
Lucien Cuénot discovered lethal alleles in 1905 while studying the inheritance of coat color in mice. The agouti gene is responsible for the color of the coat in mice. This gene codes for an agouti-signaling protein, which is responsible for melanin distribution in mammals. The wild-type allele gives rise to gray-brown coat color in mice, while the mutant allele gives rise to yellow coat color. In addition to coat color, the agouti gene is associated with the yellow...