男性鑲嵌型染色體異常45,X/46,XY之罕見案例報告及文獻分析

廖偉創、程威銘、張彰琦、邱逸淳

臺北市立聯合醫院忠孝院區外科部泌尿科

45,X/46,XY mosaicism male: rare case report and literature review

Wei-Chuang Liao, Wei-Ming Chen, Chang-Chi Chang, Yi-Chun Chiu

Division of Urology, Department of Surgery, Taipei City Hospital, Zhongxiao Branch

Introduction

45,X/46,XY mosaicism is a rare sex chromosome abnormality and probably underdiag­nosed condition with incidence 1.5 per 10,000 newborns. 45,X/46,XY mosaicism can present with a wide variety of phe­notypes resulting from involvement of different aspects of the individual, such as growth, hormone balance, gonadal develop­ment, sex of rearing and fertility. We reported a 45,X/46,XY case of young adult male with normal-appearing male phenotype.

Case presentation

A 33-year-old man without major medical history presented to urologic clinic with initial complaints of exhaustion and persistent general feeling of illness especially after orgasm. He has normal stature and masculine appearance. Physical examination normal penis length, normal position of external urethral meatus, and normal pubic hair distribution but bilaterally small testes. Blood hormonal test revealed a low serum testosterone level of 187 ng/dL. Further chromosomal evaluation and genetic analysis confirmed a 45,X/46,XY karyotype, consistent with the diagnosis of a mosaicism 45,X/46,XY (Fig. 1). Given his hypogonadism, he was started on Clomiphene citrate, which successfully raised his testosterone levels. The patient reported improved energy and an increase in general well-being, particularly noting enhanced energy and satisfaction following ejaculation.

Discussion

45,X/46,XY mosaicism is a rare chromosomal abnormality with a wide range of phenotypes in both males and females, from normal individuals with different degrees of genital ambiguity to those who show signs of Turner's syndrome [1]. Most normal-appearing male phenotype cases are diagnosed during the prenatal period, and several 45,X/46,XY adult cases with a normal male phenotye were diagnosed during infertility investigation [2]. The mosaicism ratio in different tissues may explain the variety of phenotypes in mixed gonadal dysgenesis [3]. Given the symptoms of low testosterone (primary hypogonadism), 45,X/46,XY mosaicism was diagnosed incidentally in the chromosomal analysis. Considering fertility of this unmarried case, Clomiphene citrate was administered to treat hypogonadism.

Conclusion

We reported a case of 45,X/46,XY mosaicism with a normal-appearing male phenotype and presenting with low testosterone symptoms. Comprehensive history taking and physical exam play an important role of the diagnosis of chromosome abnormality. Chromosomal analysis may be considered in male with hypogonadism and ambiguous genital appearance.