Tay–Sachs disease is an autosomal recessive neurological disorder that is fatal in infancy. Despite its invariably lethal effect, Tay–Sachs disease occurs at very high frequency in some Central and Eastern European (Ashkenazi) Jewish populations. In certain Ashkenazi populations, 1 in 750 infants has Tay–Sachs disease. Population biologists believe the high frequency is a consequence of genetic bottlenecks caused by pogroms (genocide) that have reduced the population multiple times in the past several hundred years. What is a genetic bottleneck?

Key Concepts

Genetic Bottleneck

A genetic bottleneck occurs when a population's size is significantly reduced for at least one generation, leading to a loss of genetic diversity. This reduction can result from events such as natural disasters, disease outbreaks, or human activities. The surviving population may not represent the genetic diversity of the original population, which can affect future generations' genetic variation and adaptability.

Autosomal Recessive Inheritance

Autosomal recessive inheritance is a pattern of genetic transmission where two copies of a mutated gene, one from each parent, are required for an individual to express a trait or disorder. In the case of Tay–Sachs disease, individuals must inherit the defective gene from both parents to develop the condition. Carriers, who have only one copy of the mutated gene, typically do not show symptoms but can pass the gene to their offspring.

Population Genetics

Population genetics is the study of genetic variation within populations and how these variations change over time due to factors like natural selection, genetic drift, mutation, and gene flow. It helps explain the frequency of certain genetic traits or disorders, such as Tay–Sachs disease in specific populations, by examining historical events and demographic changes that influence genetic diversity and allele frequencies.