Loss of function mutations in the PHEX gene could determine X-linked dominant hypophosphatemia. This is the most common form of genetic rickets. It is characterized by renal phosphate wasting determining an increase in fibroblast growth factor 23 (FGF-23), growth retard, bone deformities and musculoskeletal manifestations. In recent decades, analysis of the PHEX gene has revealed numerous different mutations. However, no clear genotype-phenotype correlations have been reported in patients with hypophosphatemic rickets (XLH). We report two cases of a 28-year-old-male (patient 1) and a 19-year-old male (patient 2) affected by XLH initially treated with phosphate and 1,25-dihydroxyvitamin–D admitted to the Endocrinology unit because of the persistence of muscle weakness, bone pain and fatigue. After phosphate withdrawal, both patients started therapy with burosumab and symptoms ameliorated in three months. However, patient 1’s biochemical parameters did not improve as expected so we decided to investigate his genetic asset. We herein describe a possible clinical implication for the missense “de novo” mutation, c.250G>C (p.Ala84Pro) in the PHEX gene, reported in the PHEX database and classified as a variant of uncertain significance (VUS). The clinical implication of this mutation on disease burden and quality of life in adults is still under investigation.

Gynecomastia in adolescence is a benign condition that mostly disappears spontaneously within approximately two years from onset. When it is associated with hypogonadism, it may suggest a disorder of sexual differentiation. We report the case of a young man (18 years old) with gynecomastia associated with azoospermia, small testes, hyperestrogenism and hypergonadotropic hypogonadism. A karyotype 46,XX was found, and searching for SRY (sex-determining region Y) by fluorescence in situ hybridization (FISH) highlighted the presence of the gene on the terminal region of the short arm, with breakpoints likely in Xp22.3 and Yp11.3. Implications of testosterone replacement therapy with respect to sex differentiation disorder and to physical performance are discussed.

We report a case of a 19-year-old male referred to the Endocrine Unit because of gynecomastia. Initial investigation revealed elevated levels of estradiol (E2) along with secondary hypogonadism (hypotestosteronemia and severe oligoasthenoteratozoospermia (OAT)) despite normal testicular volume (12 mL) and secondary sexual characteristics. Surprisingly, an ultrasound examination revealed a small hypoechoic mass (1.1 cm) with intense intralesional vascularization within the right testicle, even though tumor markers were normal. Surgical removal of testicular mass led to the identification of Leydigioma, and the patient showed regression of gynecomastia during the nine-month follow-up. Unexpectedly, hypergonadotropinemia manifested along with normal testosterone (T) levels and significant improvement in OAT. Magnetic resonance imaging (MRI) showed pituitary hyperplasia (PH). Gynecomastia represents an atypical manifestation of Leydig cell tumors and typically resolves after surgical removal. However, unilateral orchiectomy may determine compensatory PH. Currently, it is uncertain whether the shift from hypogonadotropic to permanent hypergonadotropinemia was the only factor responsible for the high sperm count occurring in our patient. Further research is needed to elucidate the underlying mechanisms.

Adult-onset cases of idiopathic hypogonadotropic hypogonadism (IHH) are characterized by partial or normal puberty development until adolescence and by the impairment of the hypothalamic–pituitary–gonadal (HPG) axis in adulthood. WDR11 and DCC genes are known to be involved in axonal development, particularly of hypothalamic GnRH neurons, and ciliogenesis. We report a female case of adult-onset hypogonadism and cerebellar ataxia, in which we identified two gene mutations. A panel of 48 genes was set up to search for variants in the causative genes of CHH. The variants found were analyzed following the American College of Medical Genetics and Genomics (ACMG) criteria to define their pathogenicity. We identified a missense heterozygous variant in the WDR11 gene NM_018117.12:c.2306T>G (p.Met769Arg) and a mutation in a second gene DCC resulting in amino acid substitutions NM_005215.4:c.3533C>T (p.Ser1178Phe). These variants were classified as being of uncertain clinical significance. We assume that there is a link between the variants found and the impairment of the gonadotrophic and neurological phenotype of the patient. Therefore, we propose the genetic test to identify the best therapeutic approach to identify infertility in female patients with IHH; we believe it is necessary to test WDR11 and DCC genes in larger populations with the same condition to introduce it in future protocols of assessment.