Felwah S Al-Zaid1, AbdelFattah A Alhader2, Laila Y Al-Ayadhi3. 1. Department of Physiology, College of Medicine, Riyadh, Saudi Arabia; Autism Research and Treatment Center, AL-Amodi Autism Research Chair, College of Medicine, Riyadh, Saudi Arabia. Electronic address: D_fl329@hotmail.com. 2. Department of Physiology, College of Medicine, Riyadh, Saudi Arabia. 3. Department of Physiology, College of Medicine, Riyadh, Saudi Arabia; Autism Research and Treatment Center, AL-Amodi Autism Research Chair, College of Medicine, Riyadh, Saudi Arabia.
Abstract
BACKGROUND: Autism is a neurodevelopment disorder with a strikingly higher prevalence in boys than girls. There are many theories regarding this gender bias, and prenatal exposure to high levels of fetal testosterone (FT) may be a predisposing factor. The second to fourth digit ratio (2D:4D) is the only indirect measure that reflects this association postnatally. Thus, this study measured the lengths of the index finger (2D) and the ring finger (4D) and calculated the 2D:4D ratio. Subsequently, this ratio was used to indirectly determine the potential prenatal exposure to high levels of FT in autistic children. METHODS: This case-control study was conducted with 60 male children with 31 individuals having classic-onset autism and 29 individuals serving as age-matched, healthy controls. The lengths of both the index (2D) and the ring (4D) fingers of the right hand of both autism and control groups were obtained using a scanner and the 2D:4D ratio was calculated. RESULTS: The 2D:4D ratio in the current study was significantly lower in boys with autism compared to the controls (p ≤ 0.001). CONCLUSIONS: This study demonstrates a significantly lower 2D:4D ratio in Saudi boys with autism, which indirectly suggests that these boys were exposed to high levels of prenatal FT. Accordingly, prenatal exposure to high levels of FT is a risk factor for the development of autism, and the postnatal measurement of the 2D:4D ratio could be a potential screening tool.
BACKGROUND:Autism is a neurodevelopment disorder with a strikingly higher prevalence in boys than girls. There are many theories regarding this gender bias, and prenatal exposure to high levels of fetal testosterone (FT) may be a predisposing factor. The second to fourth digit ratio (2D:4D) is the only indirect measure that reflects this association postnatally. Thus, this study measured the lengths of the index finger (2D) and the ring finger (4D) and calculated the 2D:4D ratio. Subsequently, this ratio was used to indirectly determine the potential prenatal exposure to high levels of FT in autisticchildren. METHODS: This case-control study was conducted with 60 male children with 31 individuals having classic-onset autism and 29 individuals serving as age-matched, healthy controls. The lengths of both the index (2D) and the ring (4D) fingers of the right hand of both autism and control groups were obtained using a scanner and the 2D:4D ratio was calculated. RESULTS: The 2D:4D ratio in the current study was significantly lower in boys with autism compared to the controls (p ≤ 0.001). CONCLUSIONS: This study demonstrates a significantly lower 2D:4D ratio in Saudi boys with autism, which indirectly suggests that these boys were exposed to high levels of prenatal FT. Accordingly, prenatal exposure to high levels of FT is a risk factor for the development of autism, and the postnatal measurement of the 2D:4D ratio could be a potential screening tool.
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