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Genotype

TL;DR

Section titled “TL;DR”
  • The set of alleles an individual carries, which can be identified by genetic testing or inferred from physical characteristics.
  • Helps explain inherited traits and can indicate health risks or how someone may respond to certain medications.
  • Some traits (e.g., height) are influenced by both genotype and environmental factors.

Definition

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Genotype refers to the genetic makeup of an individual, including the specific alleles that an individual inherits from their parents.

Explanation

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Genotype is defined by the specific alleles present in an individual’s genome. It can be determined directly through genetic testing or indirectly by analyzing physical characteristics such as height, eye color, or susceptibility to certain diseases. An individual’s genotype contributes to the traits they display and can affect medical considerations, including risks for genetic conditions and responses to medications. However, not all traits are determined solely by genotype; some, like height, reflect both genetic and environmental influences.

Examples

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Blood type (ABO)

Section titled “Blood type (ABO)”

The ABO blood group system has three possible alleles - A, B, and O - and individuals can inherit a combination of these alleles from their parents. For example, someone with the genotype AA would have the blood type A, while someone with the genotype BO would have the blood type B.

Eye color

Section titled “Eye color”

The gene responsible for eye color has multiple alleles, each of which can result in a different eye color. For example, someone with the genotype BB for this gene would have brown eyes, while someone with the genotype bb would have blue eyes.

Use cases

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  • Understanding an individual’s potential health risks and likelihood of developing certain genetic conditions (for example, sickle cell anemia or cystic fibrosis).
  • Predicting or explaining responses to specific medications when a genotype affects the enzyme needed to metabolize that medication.
  • Informing medical decisions by providing insight into an individual’s genetic makeup.

Notes or pitfalls

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  • Genotype does not always fully determine a trait; some traits result from interactions between genotype and environmental factors (for example, height).
Section titled “Related terms”
  • Allele
  • Genetic testing
  • Physical characteristic
  • ABO blood group system