TY - JOUR
T1 - Sex-different abnormalities in the right second to fourth digit ratio in Japanese individuals with autism spectrum disorders
AU - Masuya, Yasuhiro
AU - Okamoto, Yuko
AU - Inohara, Keisuke
AU - Matsumura, Yukiko
AU - Fujioka, Toru
AU - Wada, Yuji
AU - Kosaka, Hirotaka
N1 - Funding Information:
We thank R. Fujisawa and K. Mita for the help in collecting the data. This work was partly funded by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (25860110) and by the Takeda Science Foundation. Part of this research is the result of a project entitled “Integrated research on neuropsychiatric disorders” carried out under the Strategic Research Program for Brain Sciences by the MEXT of Japan.
Funding Information:
We thank R. Fujisawa and K. Mita for the help in collecting the data. This work was partly funded by Grants-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (25860110) and by the Takeda Science Foundation. Part of this research is the result of a project entitled "Integrated research on neuropsychiatric disorders" carried out under the Strategic Research Program for Brain Sciences by the MEXT of Japan.
Publisher Copyright:
© 2015 Masuya et al.
PY - 2015/6/9
Y1 - 2015/6/9
N2 - Background: The prevalence of autism spectrum disorders (ASDs) is higher in men than in women. The extreme male brain theory proposes that excessive prenatal testosterone activity could be a risk factor for ASDs. However, it is unclear whether prenatal sex hormone activity is a risk factor for women. The ratio of the length of the second to fourth digits (2D:4D) is considered to be a biomarker of the prenatal ratio of testosterone to estrogen. Therefore, this study compared the 2D:4D ratios of women with and without ASDs to determine if prenatal sex hormone activity could be a risk factor for ASDs in women. Methods: The study included 35 Japanese men with ASDs, 17 Japanese women with ASDs, 59 typically developed (TD) Japanese men, and 57 TD Japanese women. We measured digit lengths and compared the 2D:4D ratios among the four groups. We also examined the relationship between the 2D:4D ratio and the autism-spectrum quotient score of each group. Results: In our cohort, men with ASDs tended to have lower right-hand 2D:4D ratios relative to TD men. In contrast, the right 2D:4D ratios in women with ASDs were higher compared to those of TD women. No significant correlations were found between the 2D:4D ratios and the autism-spectrum quotient scores in any group. The higher right 2D:4D ratios in women could not be explained by age or full-scale intelligent quotients. This group difference was not found for the left 2D:4D or right-left 2D:4D ratios. Conclusions: We found a reverse direction of abnormality in the right 2D:4D ratio for men and women with ASDs. It has been posited that high prenatal testosterone levels lead to a lower 2D:4D ratio. However, a recent animal study showed that testosterone injection to dam leads to a higher right 2D:4D ratio especially for female offspring, which might be mediated by abnormal adipose accumulation in the fingertip. Therefore, the present findings suggest that high prenatal testosterone could be a risk factor both for Japanese men and women with ASDs, elucidating one potential etiology of ASDs in women.
AB - Background: The prevalence of autism spectrum disorders (ASDs) is higher in men than in women. The extreme male brain theory proposes that excessive prenatal testosterone activity could be a risk factor for ASDs. However, it is unclear whether prenatal sex hormone activity is a risk factor for women. The ratio of the length of the second to fourth digits (2D:4D) is considered to be a biomarker of the prenatal ratio of testosterone to estrogen. Therefore, this study compared the 2D:4D ratios of women with and without ASDs to determine if prenatal sex hormone activity could be a risk factor for ASDs in women. Methods: The study included 35 Japanese men with ASDs, 17 Japanese women with ASDs, 59 typically developed (TD) Japanese men, and 57 TD Japanese women. We measured digit lengths and compared the 2D:4D ratios among the four groups. We also examined the relationship between the 2D:4D ratio and the autism-spectrum quotient score of each group. Results: In our cohort, men with ASDs tended to have lower right-hand 2D:4D ratios relative to TD men. In contrast, the right 2D:4D ratios in women with ASDs were higher compared to those of TD women. No significant correlations were found between the 2D:4D ratios and the autism-spectrum quotient scores in any group. The higher right 2D:4D ratios in women could not be explained by age or full-scale intelligent quotients. This group difference was not found for the left 2D:4D or right-left 2D:4D ratios. Conclusions: We found a reverse direction of abnormality in the right 2D:4D ratio for men and women with ASDs. It has been posited that high prenatal testosterone levels lead to a lower 2D:4D ratio. However, a recent animal study showed that testosterone injection to dam leads to a higher right 2D:4D ratio especially for female offspring, which might be mediated by abnormal adipose accumulation in the fingertip. Therefore, the present findings suggest that high prenatal testosterone could be a risk factor both for Japanese men and women with ASDs, elucidating one potential etiology of ASDs in women.
KW - Autism spectrum disorders
KW - Digit ratio
KW - Etiology
KW - Prenatal estrogen
KW - Prenatal testosterone
KW - Sex difference
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U2 - 10.1186/s13229-015-0028-x
DO - 10.1186/s13229-015-0028-x
M3 - Article
AN - SCOPUS:84931066813
SN - 2040-2392
VL - 6
JO - Molecular Autism
JF - Molecular Autism
IS - 1
M1 - 34
ER -