Paris, F. Gaspari, L. Mbou, F. Philibert, P. Audran, F. Morel, Y. Lauber-Biason, Anna Sultan, C.. 2016-03-01 Pubertal gynecomastia is a common condition observed in up to 65% of adolescent males. It is usually idiopathic and tends to regress within 1–2 years. In this descriptive cross-sectional study, we investigated 25 adolescent males with prominent (>B3) and/or persistent (>2 years) pubertal gynecomastia (P/PPG) to determine whether a hormonal/genetic defect might underline this condition. Endocrine investigation revealed the absence of hormonal disturbance for 18 boys (72%). Three patients presented Klinefelter syndrome and three a partial androgen insensitivity syndrome (PAIS) as a result of p.Ala646Asp and p.Ala45Gly mutations of the androgen receptor gene. The last patient showed a 17α-hydroxylase/17,20-lyase deficiency as a result of a compound heterozygous mutation of the CYP17A1 gene leading to p.Pro35Thr(P35T) and p.Arg239Stop(R239X) in the P450c17 protein. Enzymatic activity was analyzed: the mutant protein bearing the premature stop codon R239X showed a complete loss of 17α-hydroxylase and 17,20-lyase activity. The mutant P35T seemed to retain 15–20% of 17α-hydroxylase and about 8–10% of 17,20-lyase activity. This work demonstrates that P/PPG had an endocrine/genetic cause in 28% of our cases. PAIS may be expressed only by isolated gynecomastia as well as by 17α-hydroxylase/17,20-lyase deficiency. Isolated P/PPG is not always a ‘physiological’ condition and should thus be investigated through adequate endocrine and genetic investigations, even though larger studies are needed to better determine the real prevalence of genetic defects in such patients. application/pdf https://folia.unifr.ch/global/documents/305055 https://folia.unifr.ch/documents/305055/files/lau_emi.pdf eng info:eu-repo/semantics/altIdentifier/doi/10.1111/andr.12145 info:eu-repo/semantics/openAccess License undefined Andrology. - 2016, vol. 4, no. 2, p. 263–269 adolescence disorders of sex differentiation sex hormones steroids gynecomastia info:eu-repo/classification/udc/57 Endocrine and molecular investigations in a cohort of 25 adolescent males with prominent/persistent pubertal gynecomastia http://purl.org/coar/resource_type/c_6501