Exam 21: Genetic Analysis of Quantitative Traits

GWA looks at DNA marker distribution relative to that of supposed QTLs.Therefore,which of the following would be true of linkage disequilibrium?

An increased number of patients have recently been diagnosed with celiac disease,which you may know of as gluten sensitivity (OMIM 212750).It is a multifactorial disorder of the small intestine influenced by genes and environment,and it is characterized by malabsorption due to inflammation of the mucosa after eating wheat gluten or related proteins.It is now thought to occur in 1 out of 120 to 300 people.Genes found to be associated with it are in the HLA region of chromosome 6,namely DR3 and DQw2.Which of the following is more probable?

A strain of a cereal grain can be either dark tan,medium-dark tan,medium tan,light tan,or cream colored.When a dark tan and a cream plant are crossed,all F₁ are medium tan.The F₂ are distributed in a ratio of 1:4:6:4:1 from darkest to lightest.How many genes are involved in this coloration?

It is clearly established that obesity has greatly increased in children over the last several decades in the United States.While several genes have been identified that increase the potential for obesity,environmental influences are also involved.Which of the following is most likely?

What is the statistically acceptable Lod score that provides evidence of genetic linkage?

A homozygous plant has sepals of 30-cm flowers while another homozygote of the same species has 40-cm flowers.The F₁ flowers are all 35 cm.In the F₂,out of 600 plants the smallest flowers were 30 cm and the largest were 45cm;all the others were of intermediate sizes.If all the genes involved in flower size are additive,how many gene pairs are there?

A GWA study relies on the correlation between a QTL and a ________.

Until recently,only apolipoprotein E (APOE)polymorphisms have been found to correlate with late-onset (nonfamilial)Alzheimer disease (AD);however,these account for less than 50% of the VG.New GWA studies have found a chromosome 12 risk locus.What method will likely be used by AD researchers going forward?

While most additive polygenic traits show continuous distribution,some can be divided into two or more categories based on their contribution to genetic liability.Such traits are said to have what separation between affected and unaffected members of a population?

QTLs are most often mapped relative to DNA markers by using what scores as measurement?