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INTRODUCTION AND OBJECTIVE:

Copy number variations (CNVs) are structural chromosomal defects causing microdeletions or microduplications. CNVs in the dosage-sensitive genes ADCY2, ADCY9, CRKL, KCTD13, RBFOX2, and ZEB2 occur more frequently in men with genitourinary anomalies such as cryptorchidism and hypospadias compared to the general male population. To evaluate the association of these CNVs with spermatogenic failure, the prevalence of CNVs in men with history of cryptorchidism who underwent microdissection testicular sperm extraction (mTESE) for non-obstructive azoospermia (NOA) was defined.

METHODS:

Whole blood DNA samples were collected from 101 men with cryptorchidism and NOA who presented for (mTESE) and two fertile control men. TaqMan quantitative polymerase chain reaction was used to assess copy numbers of ADCY2, ADCY9, CRKL, KCTD13, RBFOX2, and ZEB2 with each reaction performed in triplicate. Relative quantification values were obtained using CopyCaller Software. Fisher’s exact test was used to compare CNVs in cryptorchid men with NOA compared to CNV prevalence in the general male population from the Database of Genomic Variants.

RESULTS:

Of the 101 patients, 44 (44%) had bilateral cryptorchidism, 57 (56%) had unilateral cryptorchidism, and 51 (50%) had sperm retrieved with mTESE. Six patients (5.9%) had CNVs detected. Two men had microdeletions of CRKL, one had a microdeletion of ZEB2, and one had a microduplication of ADCY2. Two men with bilateral cryptorchidism had multiple CNVs detected: one had microdeletions of ADCY2, ADCY9, and RBFOX2, and one had microdeletions of ADCY9, CRKL, ZEB2 and a microduplication of KCTD13. Four of the six patients with detected CNVs (67%) had sperm retrieved on mTESE. Compared the general male population, men with cryptorchidism and NOA had higher prevalence of CNVs in ADCY2 (p=0.002), ADCY9 (p=0.004), CRKL (p<0.001), and ZEB2 (p<0.001).

CONCLUSIONS:

Approximately 6% of adult men with a history of cryptorchidism and NOA had gene dosage changes in ADCY2, ADCY9, CRKL, KCTD13, RBFOX2, or ZEB2, with two-thirds of these men having successful sperm retrieval on mTESE. As many of these CNVs are syndromic, genetic counseling may be warranted for men found to carry them. The functional consequences of these gene dosage changes on adult spermatogenesis remain to be fully elucidated.

Source of Funding:

n/a

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