The Rh blood group in humans is determined by a gene on chromosome 1. A dominant allele produces Rh+ blood type, and a recessive allele generates Rh-. Elliptocytosis is an autosomal dominant disorder that produces abnormally shaped red blood cells that have a short life span resulting in hereditary anemia. A large family with elliptocytosis is tested for genetic linkage of Rh blood group and the disease. The lod score data below are obtained for the family.

Over what range of θ do lod scores indicate significant evidence in favor of genetic linkage?

Verified step by step guidance

1. Understand the concept of a lod score: A lod score (logarithm of odds) is used in genetics to determine whether two loci are linked. A positive lod score indicates evidence of linkage, while a negative score suggests no linkage.
2. Recall the threshold for significant evidence of linkage: A lod score of 3 or higher is considered significant evidence in favor of genetic linkage, while a score of -2 or lower suggests no linkage.
3. Examine the range of recombination frequencies (θ): Lod scores are calculated for different values of θ, which represent the recombination frequency between two loci. θ ranges from 0 (complete linkage) to 0.5 (independent assortment).
4. Identify the range of θ where lod scores are ≥ 3: Look at the provided lod score data and determine the values of θ for which the lod score is 3 or higher. This range indicates significant evidence of genetic linkage.
5. Summarize the findings: Based on the data, specify the range of θ values that support genetic linkage, ensuring clarity in the interpretation of the lod score results.

Key Concepts

Genetic Linkage

Genetic linkage refers to the tendency of genes located close to each other on a chromosome to be inherited together during meiosis. This phenomenon occurs because linked genes are less likely to be separated by recombination. Understanding genetic linkage is crucial for mapping traits and diseases, as it helps determine whether two traits are inherited together more often than expected by chance.

Lod Score

A lod score (logarithm of the odds) is a statistical measure used to evaluate the likelihood of genetic linkage between a trait and a specific genetic marker. A lod score greater than 3 is typically considered significant evidence for linkage, while a score less than -2 suggests no linkage. This score helps researchers assess the probability that observed data could occur under the hypothesis of linkage versus no linkage.

Autosomal Dominant Inheritance

Autosomal dominant inheritance is a pattern where only one copy of a dominant allele is needed for an individual to express a trait or disorder. This means that an affected individual has a 50% chance of passing the trait to each offspring. Understanding this inheritance pattern is essential for predicting the likelihood of disorders, such as elliptocytosis, being passed through generations in a family.