• Testicular DSD
• ovotesticular DSD
• I-DSD registry
• gonadal function.

This study comprehends the preliminary data of an I-DSD registry study developed to better understand the gonadal function course and outcome in patients with testicular DSD (T-DSD) and ovotesticular DSD (OT-DSD). Clinical presentation, laboratory testing, auxological parameters, pubertal development and gonadal structures from birth to complete pubertal development were collected and analysed. The stretched penile length, used in this first phase as indicator of testicular tissue function, was found impaired in most of the patients from the beginning and with almost no signs of improvement in older ages. This supported the already known trend of this patients to a progressive decline of the testicular function in time. The overview of the phenotypical characteristics in this large international cohort showed a higher number of patients with atypical genitalia in the T-DSD group than expected in relation to what reported in literature. This, in association with the fact that differential diagnosis is, in most of the cases, very challenging, led to support the hypothesis that rather than two separate conditions T-DSD and OT-DSD should be considered part of the spectrum of a single pathology. Considering the two conditions as a single identity can lead to further difficulties in the sex assignment process, already complex, but it can also encourage a systematic approach that can improve the patient’s management and outcome.