Polymorphisms of Anthropological Interest

What is Lactase Persistence?

the genetic trait that allows adults to continue digesting the lactose in milk throughout their lives

Symptoms of adult-type hypolactasia?

• digestive distress after consuming dairy

• abdominal pain/cramps

• bloating

• gas

• diarrhea

Which condition is more common in mammals and humans?

lactase non-persistance

Lactase non-persistence

genetic trait where the body's production of the enzyme lactase decreases after infancy, making it difficult to digest the sugar in milk, called lactose

Lactose intolerance

the inability to fully digest lactose, a sugar in milk, leading to digestive symptoms like bloating, gas, diarrhea, and stomach pain after consuming dairy products

Lactose mal-absorption

the inability to fully digest lactose due to insufficient amounts of the enzyme lactase

Lactase Deficiency

a condition where the body produces insufficient lactase

Contrast lactase and lactose

lactose is the sugar itself, lactase is the protein that breaks it down

Steps in lactase biosynthesis

Lactase biosynthesis: roles of lactase and lactose

Genotypes of LCT gene?

Phenotypes of LCT gene?

Role of MCM6 gene in lactase synthesis?

regulatory

define population attributable risk

reduction of disease incidence if the affected population is not exposed

How might the ability to tolerate lactose be selectively advantageous?

eat dairy as an adult

What is PTC?

synthetic compound similar to natural glucosinolates

Major taster and non-taster haplotypes of the TAS2R38 gene?

• PAV: taster haplotype

• AVI: non-taster haplotype

How has the ability to taste bitter substances believed to be selectively advantageous?

evolved to detect plant poisons (bitter)

Briefly outline the presumed evolution of the bitter taste gene among primates.

gene duplication. mutation, and diverse selection pressures

Pleiotropy

one gene w/multiple phenotypic effects (includes lethal genes)

Epistasis

gene to gene interaction; one gene’s product masks or enhances the effects of another

Penetrance

frequency of expression of the phenotype

What is PKU?

What is the importance of the phenylalanine hydroxylase enzyme?

breaks down Phe to prevent toxic buildup

What are the genotypes and phenotypes of the PAH gene?

How is PKU pleiotropic?

• mental retardation

• lower range of head size

• lighter skin & hair pgmentation

• differential penetrance

How does it exhibit differential penetrance?

not everyone develops the same severity or set of symptoms

What are the epistatic effects of alkaptonuria in relation to PKU?

the PKU phenotype is epistatic to the AKU phenotype