So far apparently healthy 25-year-old white male presented to an emergency room with a chief complaint of tonic seizures. The diagnostic imaging (NMR of the head and angio-CT) showed that the man suffered from a large anterior cranial fossa tumour. The tumor was removed by the fronto-parietal craniotomy. Histopathological examination revealed it was a chondroma. The postoperative period was uneventful. Three months after the procedure, the patient presented to the emergency room with severe pain in the left hip joint. The ailment characterized as recurrent started about a year ago. A sudden increase in pain intensity occurred six months later and resulted in patient ambulation on crutches to prevent weight bearing on the affected limb. Physical examination revealed the Drehmann’s sign was positive, the left limb in the extension was rotated 45 degrees, all movements at the hip joint were excruciating. There were no vascular and nervous disturbances. The pelvis A-P and Lauenstein’s axial radiography and Computed Tomography of the pelvis were performed. Diagnostic imaging has showed bilateral opened epiphyseal cartilages of the femurs and SCFE on the left, affecting lateral and posterior part. The clinical and radiological assessment suggested proceeding with an open joint reconstruction with Dunn’s dislocation description by Ganz [, ]. The following day patient was placed in the upright position, and the rehabilitation started. After two more weeks patient was permitted to partially bear weight on the affected leg. Two months after the operation patient was able to fully bear weight on the affected limb. Three months after the operation patient regained full range of motion and walked without crutches. Endocrinological consultation was suggested due to clinical features of hypogonadism and revealed that the patient was 194 cm tall and his weight was 83 kg (BMI 22.05 kg/m2). His arm span was 197 cm. He presented features of delayed sexual maturation. Examination of external genitalia showed micropenis and testicular volume of 3.3 ml and 3.6 ml in the right and left testes, respectively (Tanner’s stage of 2). To our knowledge, these signs of delayed puberty were firstly observed during an endocrine consultation on SCFE. Laboratory tests revealed hypogonadotropic hypogonadism with no other features of pituitary insufficiency. Normal pituitary gland was visualized in NMR. The bone age was 15 years. Dual-energy X-ray absorptiometry was performed, and osteoporosis was found (Z-score at lumbar spine − 3.4). Clinical findings were also reflected in a genetic test. Direct sequencing of gonadotropin-releasing hormone receptor (GNRHR, MIM:138850, ref.: NM_000406.2) revealed compound heterozygosity for two independent mutations R139H and R262Q (each allele is affected by one mutation, Fig. ). The genetic status of a patient leads to the synthesis of altered GNRHR protein. The patient had a normal male karyotype (46XY), and other chromosomal rearrangements in the genome that could be responsible for the phenotype, were excluded. The treatment with human chorionic gonadotropin (hCG) was initiated two weeks following the surgery to achieve both masculinization and spermatogenesis. The treatment resulted in a complete restoration of phenotype and functional male sex characteristics. The patient became a father of a healthy daughter three years after treatment initiation. The anatomy and function of the operated hip joint are preserved. Figure presents patient treatment timeline. “I had always felt different. My appearance and even the way I behaved had been very different from most my collegues. After I started the therapy, my body has changed, my mood, even my voice. After several months of the therapy I felt in love for the first time in my life, and I am a happy father of a wonderful girl.”