A Study Is Undertaken to Map the HLA-DQ Loci in a Population

question 33

Multiple Choice

A study is undertaken to map the HLA-DQ loci in a population with a high incidence of celiac sprue.  High-resolution HLA typing of the DQA1 and DQB1 loci is performed using polymerase chain reaction sequencing.  The frequency of the DQA1*0501-DQB1*0201 haplotype, strongly implicated in autoimmunity, is found to be 0.2.  However, in the same population, the frequency of the DQA1*0501 allele is 0.3 and the frequency of the DQB1*0201 allele is 0.2.  Which of the following best explains the observed DQA1*0501-DQB1*0201 haplotype frequency in this population?

• A)Heteroplasmy
• B)Increased penetrance
• C)Linkage disequilibrium
• D)Pleiotropy
• E)Segregation

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Definitions:

Implicit Memory

This memory type boosts task performance by utilizing earlier experiences without the person actively recognizing these experiences.

Explicit Memory

A type of long-term memory involving conscious recollection of previous experiences or information.

Hippocampus

A region of the brain that is associated with memory forming, organizing, and storing.

Amygdala

A part of the brain's limbic system involved in emotion regulation, especially fear and pleasure responses, playing a critical role in forming emotional memories.