A 2006 genetic study of a large American family (Ikeda et al., 2006) identified genetic linkage between DNA markers on chromosome 11 and the gene producing the autosomal dominant neuromuscular disorder spinocerebellar ataxia type 5 (SCA5). The following lod score data are taken from the 2006 study:                                     Theta (θ) Value               0.01    0.05     0.10     0.20     0.30     0.40SCA5    11.02   12.26   11.94   10.04    7.26     3.77 and DNA marker A SCA5    0.35.    0.94.     1.07     0.99     0.75    0.43 and DNA marker B Based on the available information, is DNA marker A linked to the gene producing SCA5? Explain your answer.

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 is crucial for understanding how traits are passed down through generations. In the context of the question, the linkage between DNA markers and the SCA5 gene indicates that these markers can help identify the location of the gene associated with the disorder.

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 marker. A lod score greater than 3 suggests strong evidence for linkage, while a score less than -2 indicates no linkage. In the provided data, analyzing the lod scores for DNA markers A and B in relation to SCA5 will help determine if marker A is significantly linked to the disorder.

Theta (θ) Value

The theta (θ) value represents the recombination frequency between two genetic loci, indicating the probability that a crossover will occur between them during meiosis. Lower θ values suggest closer proximity and stronger linkage. In the context of the question, examining the θ values alongside the lod scores for markers A and B will provide insight into their potential association with the SCA5 gene.