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Handedness and the X chromosome: the role of androgen receptor CAG-repeat length.

Arning L, Ocklenburg S, Schulz S, Ness V, Gerding WM, Hengstler JG, Falkenstein M, Epplen JT, Güntürkün O, Beste C - Sci Rep (2015)

Bottom Line: Mixed-handedness in men was significantly associated with longer CAG-repeat blocks and women homozygous for longer CAG-repeats showed a tendency for stronger left-handedness.These results suggest that handedness in both sexes is associated with the AR CAG-repeat length, with longer repeats being related to a higher incidence of non-right-handedness.Since longer CAG-repeat blocks have been linked to less efficient AR function, these results implicate that differences in AR signaling in the developing brain might be one of the factors that determine individual differences in brain lateralization.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Genetics, Ruhr-University, 44780 Bochum, Germany.

ABSTRACT
Prenatal androgen exposure has been suggested to be one of the factors influencing handedness, making the androgen receptor gene (AR) a likely candidate gene for individual differences in handedness. Here, we examined the relationship between the length of the CAG-repeat in AR and different handedness phenotypes in a sample of healthy adults of both sexes (n = 1057). Since AR is located on the X chromosome, statistical analyses in women heterozygous for CAG-repeat lengths are complicated by X chromosome inactivation. We thus analyzed a sample of women that were homozygous for the CAG-repeat length (n = 77). Mixed-handedness in men was significantly associated with longer CAG-repeat blocks and women homozygous for longer CAG-repeats showed a tendency for stronger left-handedness. These results suggest that handedness in both sexes is associated with the AR CAG-repeat length, with longer repeats being related to a higher incidence of non-right-handedness. Since longer CAG-repeat blocks have been linked to less efficient AR function, these results implicate that differences in AR signaling in the developing brain might be one of the factors that determine individual differences in brain lateralization.

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Related in: MedlinePlus

Handedness LQ in relation to the AR CAG-repeat length for the 77 female participants with homozygous CAG-repeat genotypes.The black line indicates the central tendency of the relationship between the two variables.
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f3: Handedness LQ in relation to the AR CAG-repeat length for the 77 female participants with homozygous CAG-repeat genotypes.The black line indicates the central tendency of the relationship between the two variables.

Mentions: Additionally, to investigate the influence of CAG-repeat length in females independent of X inactivation, a separate analysis of the 77 female participants with homozygous CAG-repeat genotypes was conducted. For Direction 1 (t(75) = −1.76; p = 0.08), Direction 2 (F(2, 74) = 1.17; p = 0.31; MSError = 4.01) and Consistency (t(75) = 0.79; p = 0.43) the effect failed to reach significance. While no significant correlation between CAG-repeat length and absolute LQ was observed (r = −0.11; p = 0.31; polyserial correlation coeffient: −0.11), a strong trend was recognizable for a correlation between CAG-repeat length and LQ (r = −0.22; p = 0.05; polyserial correlation coeffient: r:−0.22), indicating that in homozygous women longer CAG-repeats had a tendency to be related with stronger left-handedness (Fig. 3).


Handedness and the X chromosome: the role of androgen receptor CAG-repeat length.

Arning L, Ocklenburg S, Schulz S, Ness V, Gerding WM, Hengstler JG, Falkenstein M, Epplen JT, Güntürkün O, Beste C - Sci Rep (2015)

Handedness LQ in relation to the AR CAG-repeat length for the 77 female participants with homozygous CAG-repeat genotypes.The black line indicates the central tendency of the relationship between the two variables.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4321186&req=5

f3: Handedness LQ in relation to the AR CAG-repeat length for the 77 female participants with homozygous CAG-repeat genotypes.The black line indicates the central tendency of the relationship between the two variables.
Mentions: Additionally, to investigate the influence of CAG-repeat length in females independent of X inactivation, a separate analysis of the 77 female participants with homozygous CAG-repeat genotypes was conducted. For Direction 1 (t(75) = −1.76; p = 0.08), Direction 2 (F(2, 74) = 1.17; p = 0.31; MSError = 4.01) and Consistency (t(75) = 0.79; p = 0.43) the effect failed to reach significance. While no significant correlation between CAG-repeat length and absolute LQ was observed (r = −0.11; p = 0.31; polyserial correlation coeffient: −0.11), a strong trend was recognizable for a correlation between CAG-repeat length and LQ (r = −0.22; p = 0.05; polyserial correlation coeffient: r:−0.22), indicating that in homozygous women longer CAG-repeats had a tendency to be related with stronger left-handedness (Fig. 3).

Bottom Line: Mixed-handedness in men was significantly associated with longer CAG-repeat blocks and women homozygous for longer CAG-repeats showed a tendency for stronger left-handedness.These results suggest that handedness in both sexes is associated with the AR CAG-repeat length, with longer repeats being related to a higher incidence of non-right-handedness.Since longer CAG-repeat blocks have been linked to less efficient AR function, these results implicate that differences in AR signaling in the developing brain might be one of the factors that determine individual differences in brain lateralization.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Genetics, Ruhr-University, 44780 Bochum, Germany.

ABSTRACT
Prenatal androgen exposure has been suggested to be one of the factors influencing handedness, making the androgen receptor gene (AR) a likely candidate gene for individual differences in handedness. Here, we examined the relationship between the length of the CAG-repeat in AR and different handedness phenotypes in a sample of healthy adults of both sexes (n = 1057). Since AR is located on the X chromosome, statistical analyses in women heterozygous for CAG-repeat lengths are complicated by X chromosome inactivation. We thus analyzed a sample of women that were homozygous for the CAG-repeat length (n = 77). Mixed-handedness in men was significantly associated with longer CAG-repeat blocks and women homozygous for longer CAG-repeats showed a tendency for stronger left-handedness. These results suggest that handedness in both sexes is associated with the AR CAG-repeat length, with longer repeats being related to a higher incidence of non-right-handedness. Since longer CAG-repeat blocks have been linked to less efficient AR function, these results implicate that differences in AR signaling in the developing brain might be one of the factors that determine individual differences in brain lateralization.

Show MeSH
Related in: MedlinePlus