Gender Bias and Fetal Testosterone and RORA in Autism Spectrum Disorder

Undergraduate #47
Discipline: Biological Sciences
Subcategory: Cell and Molecular Biology

Ajaicia Hopkins - Claflin University
Co-Author(s): Joyce E. Brown, Syeda A. Madiha, Krishna C Addanki, Gregory R. Goodwin, Pratima Pandey and Omar Bagasra

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Autism Spectrum Disorder (ASD) is a set of complex developmental disorders whose etiology is unknown. Although the symptoms may vary from person to person, they include impairment or loss of speech, lack of empathy, and social interaction deficiency. The cases of ASD have continued to increase drastically each year, with the CDC estimating 1:45 children diagnosed, from 1 in 10,000 40 years ago. It is believed that the ASD is caused by a combination of genetic and environmental factors, but recent studies suggest that epigenetic factors as well as exposure to environmental chemicals may play a critical role in its pathogenesis. Although there are no biomarkers for the disease, low levels of oxytocin (OXY) have been reported. This neuropeptide plays a critical role in neurodevelopment of social interaction. Numerous studies have shown that children with autism have plasma levels of OXY that is appreciably lower than average. Hypothesis: The importance for normal OXY and OXY receptor (OTR) function in males may explain how hormonal malfunction leads to ASD male bias. There is an inexplicable bias toward males in classical autism by a ratio of ~4:1, and ~10:1 in Asperger’s syndrome (AS). The clinical picture is very heterogeneous and the etiology is unknown although several hypotheses have been advanced including: (1) epigenetic mechanisms ‘the extreme male brain’ hypothesis of Baron-Cohen which postulates that elevated fetal testosterone (T) is a risk factor for ASD; (2) genetic mechanisms which involves X or Y chromosome inactivation; (3) Recently, Hu et al have shown that retinoic acid-related orphan receptor alpha (RORA) is reduced in the brains of multiple cohorts of individuals with ASD. This gene targets CYP19A1 (aromatase), in a gender-dependent manner that can also lead to elevated T levels, a proposed risk factor for autism. To date, none of these hypotheses have been either proven or disproven. Given the high clinical heterogeneity of ASD, it is possible that each of these mechanisms for gender bias may apply to specific cohorts of individuals with ASD. Methods and Controls; Using a large numbers of frozen amniotic fluids (AF) Baron-Cohen e al determined that normotypic children’s AF on average had 0.64 nM/L of T, autistic children 0.82 nM/L and AS children showed 1.2 nM/L. Results: Using male and female neuroblastoma cell lines, that were exposed to similar levels of T for 3-7 days and determined that neurons exposed to higher than normal levels of T exhibited significant neuromodifications at morphologic and immunologic levels. Most significantly, the downregulation of OTR in male as compared to female was observed. In addition, there were significant differential expressions of both RORA and CYP19A1 between male and female cell lines as compared to respective controls (i.e. 064 nM/L T). Conclusions: This is the first report on environment x genetic connection and gender bias at the cellular and molecular levels in ASD.

Funder Acknowledgement(s): HBCU-UP

Faculty Advisor: Omar Bagasra, obagasra@claflin.edu

Role: I unfroze and froze cells, cultured them under the hood by feeding and separating them into separate flasks so they can continue to grow, and stained them using H&E staining techniques and counted the cells under the microscope.