The complex process of sexual differentiation is known to be influenced by biological and environmental determinants. The present review has the aim of summarizing the most relevant studies on the biological basis of sexual development, and in particular, it focuses on the impact of sex hormones and genetic background on the development of sexual differentiation and gender identity. The authors conducted a search of published studies on Medline (from January 1948 to December 2019). The evidence suggests that the sexual dimorphic brain could be the anatomical substrate of psychosexual development, on which gonadal hormones may have a shaping role during prenatal and pubertal periods. Additionally, according to several heritability studies, genetic components may have a role, but a promising candidate gene has not been identified. Even though growing evidence underlines the primary role of biological factors on psychosexual development, further studies are necessary to better explain their complex interactions.

Introduction: To date no standardized hormonal treatment protocols for non-binary transgender individuals have been described in the literature and there is a lack of data regarding their efficacy and safety. Objectives: To suggest possible treatment strategies for non-binary transgender individuals with non-standardized requests and to emphasize the importance of a personalized clinical approach. Methods: A narrative review of pertinent literature on gender-affirming hormonal treatment in transgender persons was performed using PubMed. Results: New hormonal treatment regimens outside those reported in current guidelines should be considered for non-binary transgender individuals, in order to improve psychological well-being and quality of life. In the present review we suggested the use of hormonal and non-hormonal compounds, which—based on their mechanism of action—could be used in these cases depending on clients’ requests. Conclusion: Requests for an individualized hormonal treatment in non-binary transgender individuals represent a future challenge for professionals managing transgender health care. For each case, clinicians should balance the benefits and risks of a personalized non-standardized treatment, actively involving the person in decisions regarding hormonal treatment.

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Introduction As far as we know, no studies to date have investigated the psychobiological correlates of sexual distress (SD) nor the impact of hormonal treatment (HT) on SD in transgender persons. Aim To evaluate the psychobiological correlates of SD and assess the effects of HT on SD in transgender persons without gender-affirming surgery. Methods A consecutive series of 301 transgender persons (160 transwomen and 141 transmen) was considered for the cross-sectional study, and a subset of 72 subjects was studied in a 2-year follow-up. A physical examination was performed. Blood samples were drawn for determination of cortisol levels. Subjects completed psychometric measures. During 2 years of HT, the evaluation of SD was prospectively repeated. Main Outcome Measure Psychobiological correlates of SD in transgender population. Changes in SD during gender affirming hormonal treatment. Clinical Implications Knowing how hormonal treatment influence SD will help care providers when counseling transgender people. Strengths & Limitations To the authors’ knowledge, this is the first study prospectively evaluating the impact of gender affirming hormonal treatment on sexual distress in transgender individuals. The main limitations are represented by the small size of the sample and the use of questionnaires validated only in the cisgender population. Results SD showed a positive correlation with body uneasiness (P < .0001) and with dissatisfaction toward gender-related body parts or shapes (all P < .05). In addition, SD correlated positively with general psychopathology (P < .0001), alexithymia, social anxiety, and humiliation scales (all P < .05). In transmen, SD was positively associated with autism levels (P < .005), as well as with cortisol levels (P < .02). A significant correlation between SD and perceived discrimination was observed in transwomen (P < .05). In transwomen, SD was positively associated with hair density and negatively with breast growth (both P < .05). Finally, in transmen, a negative correlation was found between SD and hair density (P < .05). When the impact of HT on SD was evaluated, a significant reduction of SD was observed across time in both transwomen and transmen (P = .001 and P = .01, respectively). Conclusions The present results support the efficacy of HT in reducing SD in transgender persons.