Walum et al. Genetic variation in the AVP receptor 1a (AVPR1a) assocaitse with pair-bonding behavior in humans

Question 1

Describe the sample. Approz how many couples were included?

Answer 1

The sample consisted of 552 twin pairs and their spouses from the second cohort of the Twin and Offspring Study in Sweden (TOSS)

• consisted of couples who were together for a minimum of 5 years
• the twins were sent a questionnaire prior to the study
• DNA was extracted from a mouth wash sample
• 82% of couples were married, the other 18% were unmarried but living together (cohabitation)

Question 2

In what part of the gene was this variation seen - the promoter region or the coding sequence?

Answer 2

Promoter region

- 5’ flanking region

Question 3

What was the frequency distribution for number of copies of the 334 allele in men in this population? That is, how many had no copies, 1 or 2 copies for that allele?

Answer 3

0 copies - (457 married, 96 umarried) total = 553 
1 copy - (257 married, 52 unmarried) total = 327 
2 copies (28 married, 13 unmarried) total = 41

Question 4

One of the behavioral measures was the Partner Bonding Scale (PBS). This was a questionnaire given to both partners. Provide two of the questions from this scale.

Question 5

What correlations were seen between scores on the PBS (Pair Bonding Scale) and the presence of allele 334 in men and women? This allele also had a dose-dependent affect. What does that mean?

Answer 5

• the allele is associated with partner bonding and martial status from men ONLY
• consistent with the comparison to male prairie voles
• a dose-dependent effect of the number of 334 allels on the PBS score (table 3) was found, with carriers of two alleles showing the lowest score.
  The size of these effects were d=0.27 between men not carrying any 334 allele and 334 heterozygotes.
  d=0.38 between men not carrying and 334 allele and 334 homozygotes

Question 6

How was marital quality measured in the men and women in this study?

Answer 6

Marital quality was measured by pair bonding scale and social readjustment rating scale

Question 7

What was the relation of the 334 allele in men to marital quality measured in men?

Answer 7

men with 334 allele were more likely to be unmarried

Question 8

What was the relation of the 334 allele in men to marital quality measured in woman?

Answer 8

Women who were married to men that were homozygous for 334 allele reported a lower marital quality (via social readjustment rating scale)

Question 9

Describe the nature of the variation in the avpr1a gene in prairie voles and people.
Was the same type of genetic variation seen in voles and humans?

Answer 9

• Genetic variation lead to a change in social behavior (pair bonding) for both humans and voles
• The nature of the variation suggests that there is an association with the analogous to the behavior seen in voles
• Variation in both humans and voles

Question 10

How do variation in this gene affect expression of the avpr1a in the brains of prairie voles? How was variation in expression of this receptor measured in the brains of prairie voles?

Question 11

In male prairie voles variation in this gene affected expression of the avpr1a in the olfactory bulb, thus potentially affecting social recognition memory. Where might oyu look for analogous changes in expression in the human brain? What method or methods could be used to examine this in human brains?

Answer 11

• An association between the length of RS3 repeat and the amount of hippocampal mRNA in human postmortem tissue has been reported
• A recent study in healthy subjects suggests that the 334 allele is associated with increased activation of amygdala, a brain region known to be of importance for pair-bonding behavior

Question 12

Allele

Answer 12

One or two ore alternative forms of a gene that arise by mutation and are found at the same place on a chromosome

Question 13

Polymorphic

Answer 13

Quality or state of existing in or assuming different forms

Question 14

Homozygote

Answer 14

Individual that has two identical alleles for a particular gene

Question 15

Heterozygote

Answer 15

Individuals has two different alleles of a particular gene.

Question 16

Use a sentence or two to describe the results of Walum et al. (2008) that includes the 4 terms: allele, polymorphic, homo and heterozygote.

Answer 16

Men homozygous (rather than heterozygous) for the R334 allele were more likely to be unmarried. 
The results from the current study suggest an association between avpr1a polymorphism and human pair-bonding behavior possibly analogous to that reported for voles.