study design question

This forum made possible through the generous support of SDN members, donors, and sponsors. Thank you.

MudPhud20XX

Full Member
10+ Year Member
Joined
Nov 26, 2013
Messages
1,352
Reaction score
193
a question like this just throws me off. I just don't know what to do. can anyone help me out?

A study of 20 adults with attention-deficit/hyperactivity disorder (ADHD) and 20 age-matched adults without ADHD showed an increase in dopamine transporter protein density by single-photon emission computed tomography (SPECT) in the brain. Medication was withheld from the affected group for 1 month to eliminate the potential of induced upregulation of the gene. Analysis of the dopamine transporter gene identified a 10–base pair (bp) repeat in the 3’ untranslated region (UTR). The presence of a 9-bp allele and single nucleotide mutations in the 10-bp repeat is associated with differences in dopamine transporter gene expression. What larger population study design will provide the strongest association between the dopamine transporter and ADHD?
 
yeah, i chose case control and got this wrong. the answer is actually B. this is not from either kaplan nor UW. so is it b/c ADHD is highly genetically inheritable??? i feel like that's why, but let me hear others thoughts... thank you.

ASP studies are model-free (nonparametric) methods that use sibling concordance for a disease. Siblings are analyzed to determine whether affected siblings share alleles at loci more frequently than 50%. In this case, information about sharing particular 10-bp alleles and the dopamine transporter gene would be highly valuable. It would not provide information about how the 10-bp allele affected regulation of the gene, but it could provide information that it did or did not. It also does not provide information about other causative alleles unless the ASP study is designed to include genome scans of other genes or regions.

Case-control studies often involve an affected individual and unaffected spouse. Comparison is made between the individuals with the disease and those without with respect to family history of disease, including information about environmental exposure, occupation, geographic location, parity, and previous illness. The frequency of the disease in extended families is compared with suitable controls, matched for age and ethnicity. The most problematic area for these studies is ascertainment bias, in which relatives of affected individuals are more likely to report than the relatives of unaffected individuals. Recall bias is another area of concern. A stronger study would be a case-parent trio study.
Large-scale drug study is correct. The small study does not demonstrate an affect of medications on dopamine transporter expression. These individuals had not been on medication for a month. Studies show that patients who have never been on medication also have increased dopamine transporter genes.
 
Top