男性不孕症一項未被充分認識的原因：XYY症候群

蕭伯任^{1, 2}、楊旻鑫^{1, 2}

¹中山醫學大學附設醫學泌尿科；²中山醫學大學醫學研究所

An Underrecognized Cause of Male Subfertility: 47,XYY syndrome

Po-Ren Hsiao^{1, 2}、Ming-Hsin Yang ^{1, 2}

¹Department of Urology, Chung Shan Medical University Hospital, Taichung, Taiwan;² Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan

Introduction

47,XYY syndrome is an underrecognized sex chromosome aneuploidy with largely subtle phenotypic features. Despite preserved endocrine function, emerging evidence suggests an association with impaired spermatogenesis. It is increasingly identified incidentally, yet its clinical relevance in adult urology remains insufficiently appreciated.

Case Presentation

A 29-year-old man was referred to our clinic for evaluation of primary infertility. He had no significant past medical history and reported normal pubertal development. Physical examination revealed normal male secondary sexual characteristics. However, bilateral vas deferens were not palpable on scrotal examination.

Laboratory evaluation demonstrated a serum prolactin level of 8.77 ng/mL, total testosterone of 4.9 ng/mL, follicle-stimulating hormone (FSH) of 3.18 mIU/mL, luteinizing hormone (LH) of 2.55 mIU/mL, and prostate-specific antigen (PSA) of 2.99 ng/mL, all within reference ranges. Semen analysis revealed azoospermia, with both sperm count and motility recorded as zero. Pelvic magnetic resonance imaging (MRI) demonstrated suspected hypoplasia or absence of bilateral seminal vesicles and vas deferens.

Given the findings of azoospermia with absent vas deferens, genetic evaluation was pursued. Karyotype analysis revealed 47,XYY syndrome, confirming the diagnosis.

Discussion and Review

This case highlights 47,XYY syndrome as an underrecognized cause of male subfertility. Despite preserved testosterone levels, abnormalities in spermatogenesis and increased sperm aneuploidy may impair fertility. Unlike Klinefelter syndrome, the absence of overt hypogonadism may delay diagnosis. Genetic evaluation should be considered in unexplained infertility to facilitate appropriate counseling and management.