Expanding the reproductive organ phenotype of CHD7-spectrum disorder.

CHD7 disorder is a multiple congenital anomaly syndrome with a highly variable phenotypic spectrum, and includes CHARGE syndrome. Internal and external genital phenotypes frequently seen in CHD7 disorder include cryptorchidism and micropenis in males, and vaginal hypoplasia in females, both thought to be secondary to hypogonadotropic hypogonadism. Here, we report 14 deeply phenotyped individuals with known CHD7 variants (9 pathogenic/likely pathogenic and 5 VOUS) and a range of reproductive and endocrine phenotypes. Reproductive organ anomalies were observed in 8 of 14 individuals and were more commonly noted in males (7/7), most of whom presented with micropenis and/or cryptorchidism. Kallmann syndrome was commonly observed among adolescents and adults with CHD7 variants. Remarkably, one 46,XY individual presented with ambiguous genitalia, cryptorchidism with Müllerian structures including uterus, vagina and fallopian tubes, and one 46,XX female patient presented with absent vagina, uterus and ovaries. These cases expand the genital and reproductive phenotype of CHD7 disorder to include two individuals with genital/gonadal atypia (ambiguous genitalia), and one with Müllerian aplasia.

Adverse Birth Experiences and Parent Adjustment Associated With Atypical Genital Appearance Due to Differences of Sex Development.

OBJECTIVE: Differences/disorders of sex development (DSDs) are rare, congenital conditions involving discordance between chromosomes, gonads, and phenotypic sex and are often diagnosed in infancy. A key subset of parents of children newly diagnosed with a DSD experience clinically elevated distress. The present study examines the relationship between perinatal factors (i.e., gestational age, delivery method) and trajectories of parental adjustment. METHODS: Parent participants (mothers = 37; fathers = 27) completed measures at baseline, 6- and 12-month follow-up. Multilevel linear regression controlled for clustering of the data at three levels (i.e., time point, parent, and family) and examined the relationship between perinatal factors and trajectories of depressive and anxious symptoms. Two-way interactions between perinatal factors and parent type were evaluated. RESULTS: Overall depressive and anxious symptoms decreased over time. There were significant interactions between gestational age and parent type for depressive and anxious symptoms, with younger gestational age having a stronger negative effect on mothers vs. fathers. There was a significant interaction between time and gestational age for depressive symptoms, with 36 weeks' gestational age demonstrating a higher overall trajectory of depressive symptoms across time compared to 38 and 40 weeks. Findings for the delivery method were not significant. CONCLUSIONS: Findings uniquely demonstrated younger gestational age was associated with increased depressive symptoms, particularly for mothers compared to fathers. Thus, a more premature birth may predispose parents of infants with DSD to distress. Psychosocial providers should contextualize early diagnosis-related discussions within stressful birth experiences when providing support.

Quantifying Glans Width Changes in Response to Preoperative Androgen Stimulation in Patients Undergoing Hypospadias Repair.

PURPOSE: Testosterone (T) administration prior to hypospadias surgery to increase glans size remains controversial. Understanding T's effect on glans width (GW) is essential to understanding its potential impact on surgical outcomes. We hypothesized that preoperative T in prepubertal boys significantly increases GW at the time of hypospadias surgery. MATERIALS AND METHODS: Our single institutional database was queried to identify patients who underwent hypospadias surgery from 2016 to 2020, in which data for T administration and GW were available. Descriptive, nonparametric and categorical statistics were performed as indicated. RESULTS: A total of 579 patients were eligible for analysis. Median age at surgery was 0.9 years (IQR 0.6-1.6). A total of 247/579 patients (42.7%) received T. The median GW at surgery was 15 mm (IQR 13-17). When comparing patients who had T administered to those who did not, we found a significant difference in GW at surgery (16 mm vs 14 mm, p <0.001). The median change in GW from the office to surgery was 4 mm for those receiving T vs 0 mm for those not receiving T (p <0.001). We identified a greater change in GW from preoperative to intraoperative measurements in patients who received 2 doses of T vs 1 dose (4 mm vs 2 mm, p <0.001). A histogram plot revealed the distribution of GW change at surgery. CONCLUSIONS: In our prospectively collected cohort of patients undergoing hypospadias surgery, we were able to quantitate the change in GW from preoperative T. Two doses of T resulted in a significant increase in GW vs 1 dose.

Expanding the Use of Nephron-Sparing Surgery for Wilms Tumor.

Radical nephrectomy combined with contemporary chemotherapeutic and radiation therapy protocols has drastically improved outcomes for children with Wilms tumor. Patients with bilateral disease and a syndrome predisposing to tumor development have necessitated the use of nephron-sparing surgery in select cases. Success in managing these patients has increased the indication for partial nephrectomy, although current guidelines for unilateral Wilms tumor are limited. Given that children are being cured with increasing success, recent focus has shifted to long-term health outcomes in addition to tumor treatment. Specifically, renal function has an impact on long-term cardiovascular health and events. Adult outcomes with partial nephrectomy provide a guideline for a paradigm shift in the management of children with Wilms tumor, particularly with advances in imaging and adjuvant therapy. The data are limited for children undergoing partial nephrectomy for unilateral Wilms tumor and outcomes for larger tumors will need to be studied closely in future trials. Increased utilization of neoadjuvant chemotherapy could further expand the number of patients eligible for partial nephrectomy.

Total Motile Sperm Count in Adolescent Boys with Varicocele is Associated with Hormone Levels and Total Testicular Volume.

PURPOSE: The risk factors for future infertility in adolescents with varicocele are controversial, and little is known about the association between hormone levels and semen parameters. Semen analysis is likely the closest marker of fertility but may be difficult to obtain in some boys secondary to personal, familial or religious reasons. Identifying other clinical surrogates for abnormal semen parameters may offer an alternative for assessing varicocele severity in these boys. We hypothesized that hormone levels and total testicular volume are predictive of abnormal total motile sperm count. MATERIALS AND METHODS: We retrospectively reviewed Tanner 5 boys with palpable left varicoceles who underwent a semen analysis and had serum hormone levels tested (luteinizing hormone, follicle-stimulating hormone, inhibin B, anti-müllerian hormone and/or total testosterone) within a 6-month period. Total testicular volume was also calculated. Abnormal total motile sperm count was defined as <9 million sperm per ejaculate. RESULTS: A total of 78 boys (median age 17.2 years, IQR 16.5-18.0) were included. Luteinizing hormone, anti-müllerian hormone and total testosterone were not correlated with any semen analysis parameter. There was a negative correlation between follicle-stimulating hormone and total motile sperm count (ρ -0.35, p=0.004) and positive correlation between inhibin B and total motile sperm count (ρ 0.50, p <0.001). Total testicular volume was significantly positively correlated with total motile sperm count (ρ 0.35, p=0.01). ROC analyses revealed an optimal follicle-stimulating hormone cutoff of 2.9, an optimal inhibin B cutoff of 204 and an optimal total testicular volume cutoff of 34.4 cc to predict abnormal total motile sperm count. CONCLUSIONS: Total motile sperm count is inversely associated with follicle-stimulating hormone levels, and directly associated with inhibin B levels and total testicular volume. Optimized cutoffs for serum follicle-stimulating hormone, inhibin B and total testicular volume may prove to be reasonable surrogates for total motile sperm count in boys who defer semen analysis for personal or religious/cultural reasons.

Kidney Outcomes and Hypertension in Survivors of Wilms Tumor: A Prospective Cohort Study.

OBJECTIVE: To assess the prevalence of therapy-related kidney outcomes in survivors of Wilms tumor (WT). STUDY DESIGN: This prospective cohort study included survivors of WT who were ≥5 years old and ≥1 year from completing therapy, excluding those with preexisting hypertension, prior dialysis, or kidney transplant. Participants completed 24-hour ambulatory blood pressure monitoring (ABPM). Abnormal blood pressure (BP) was defined as ≥90th percentile. Masked hypertension was defined as having normal office BP and abnormal ABPM findings. Urine was analyzed for kidney injury molecule-1, interleukin-18, epidermal growth factor, albumin, and creatinine. The estimated glomerular filtration rate (eGFR) was calculated using the bedside chronic kidney disease in children equation. Recent kidney ultrasound examinations and echocardiograms were reviewed for contralateral kidney size and left ventricular hypertrophy, respectively. Clinical follow-up data were collected for approximately 2 years after study enrollment. RESULTS: Thirty-two participants (median age, 13.6 years [IQR, 10.5-16.3 years]; 75% stage 3 or higher WT) were evaluated at a median of 8.7 years (IQR, 6.5-10.8 years) after therapy; 29 participants underwent unilateral radical nephrectomy, 2 bilateral partial nephrectomy, and 1 radical and contralateral partial nephrectomy. In this cohort, 72% received kidney radiotherapy and 75% received doxorubicin. Recent median eGFR was 95.6 mL/min/1.73 m2 (IQR, 84.6-114.0; 11 [34%] had an eGFR of <90 mL/min/1.73 m2). Abnormal ABPM results were found in 22 of 29 participants (76%), masked hypertension in 10 of 29 (34%), and microalbuminuria in 2 of 32 (6%). Of the 32 participants, 22 (69%) had abnormal epidermal growth factor; few had abnormal kidney injury molecule-1 or interleukin-18. Seven participants with previous unilateral nephrectomy lacked compensatory contralateral kidney hypertrophy. None had left ventricular hypertrophy. CONCLUSIONS: In survivors of WT, adverse kidney outcomes were common and should be closely monitored.

Time to Complication Detection after Primary Pediatric Hypospadias Repair: A Large, Single Center, Retrospective Cohort Analysis.

PURPOSE: Controversy remains within the pediatric urology community regarding adequate duration of followup after hypospadias repair. Some have suggested that minimal long-term followup is necessary due to a low incidence of late complications. The objective of this study was to delineate time to complication detection for primary hypospadias repairs. MATERIALS AND METHODS: We queried our prospectively maintained hypospadias database and identified all patients undergoing primary hypospadias repair from June 2007 to June 2018. Patients were excluded if they had undergone primary repair elsewhere or did not have a followup visit. Complications were defined by the need for an additional unplanned surgical procedure. Kaplan-Meier analysis was performed to assess time to complication by degree of hypospadias. RESULTS: A total of 1,280 patients met inclusion criteria, of whom 976 (68.9%) underwent distal, 64 (4.9%) mid shaft and 240 (18.8%) proximal hypospadias repair. Complication rates were 10.7% (104 patients), 18.8% (12) and 53.8% (129, p<0.0001) for distal, mid shaft and proximal hypospadias repair, respectively. Only 47% of complications were detected within the first year postoperatively. Median time to complication for all repair types was 69.2 months (IQR 23 to 131.9), ie 83.1 months (IQR 42.0 to 131) for patients undergoing distal repair and 29.4 months (IQR 11.9 to 82.1) for patients undergoing proximal repair (p <0.001). CONCLUSIONS: In our large single institution series of pediatric patients undergoing hypospadias repair fewer than half of the complications presented within the first year postoperatively. Long-term followup is recommended for patients undergoing hypospadias repair to adequately detect and address complications.

Patient and Caregiver Attitudes toward Disorders of Sex Development Nomenclature.

PURPOSE: The medical terminology applied to differences/disorders of sex development has been viewed negatively by some affected individuals. A clinical population of patients with differences/disorders of sex development and their caregivers were surveyed regarding current nomenclature, hypothesizing that those unaffiliated with support groups would have more favorable attitudes. MATERIALS AND METHODS: We recruited English and Spanish speaking patients 13 years old or older with differences/disorders of sex development and their caregivers at 5 national tertiary care clinics from July 2016 to December 2018. No diagnoses were excluded. Participants completed a survey rating terminology commonly applied to differences/disorders of sex development. Responses were compared between subgroups, including members vs nonmembers of a support group. RESULTS: Of 185 potential participants approached 133 completed the survey (72% response rate). Congenital adrenal hyperplasia (33%) was the most common diagnosis. "Variation of sex development" was the most liked term (37%) but was not liked more significantly than "disorders of sex development" (27%, p=0.16). No term was liked by a majority of respondents. "Disorders of sex development" (37%) and "intersex" (53%) were the only terms most frequently viewed unfavorably. Support group members were significantly more likely to dislike the term "intersex" (p=0.02) and to like "variation of sex development" (p=0.02). CONCLUSIONS: A clinical population of patients and their caregivers had generally neutral attitudes toward nomenclature applied to differences/disorders of sex development. Members of a support group had clearer terminology preferences. "Variation of sex development" was the most liked term, and "disorders of sex development" and "intersex" were the most disliked. No term was liked by most respondents, and no clear alternative to the present nomenclature was identified.

Anomalies of the genitourinary tract in children with 22q11.2 deletion syndrome.

The 22q11.2 deletion syndrome (22q11.2DS) involves multiple organ systems with variable phenotypic expression. Genitourinary tract abnormalities have been noted to be present in up to 30-40% of patients. At our institution, an internationally recognized, comprehensive, and multidisciplinary 22q11.2DS care center has been providing care to these children. We sought to report on the incidence of genitourinary tract anomalies in this large cohort and, therefore, retrospectively reviewed all patients who underwent a complete evaluation from 1992 to March 2017. We identified all children with any genital or urinary tract anomaly. For all children with a diagnosis of hydronephrosis, the underlying etiology was determined, when possible. Overall, 1,073 of 1,267 children with 22q11.2DS underwent renal evaluations at our institution. Hundered Sixty-Two (15.1%) children had structural abnormalities of their kidneys/urinary tracts. The majority of children with hydronephrosis (63%) had isolated upper tract dilation without any additional diagnoses. Boys were significantly more likely to be diagnosed with a genital abnormality than girls (7.7 vs. 0.5%, p < 0.001). Of the 649 boys in the entire cohort, 24 (3.7%) had cryptorchidism and 24 (3.7%) had hypospadias, which was noted to be mild in all except one boy. Overall, findings of hydronephrosis, unilateral renal agenesis, and multicystic dysplastic kidney occur at higher rates than expected in the general population. Given these findings, in addition to routine physical examination, we believe that all patients with 22q11.2DS warrant screening RBUS at time of diagnosis.

What is new with 22q? An update from the 22q and You Center at the Children's Hospital of Philadelphia.

22q11.2 deletion syndrome (22q11.2DS) is a disorder caused by recurrent, chromosome-specific, low copy repeat (LCR)-mediated copy-number losses of chromosome 22q11. The Children's Hospital of Philadelphia has been involved in the clinical care of individuals with what is now known as 22q11.2DS since our initial report of the association with DiGeorge syndrome in 1982. We reviewed the medical records on our continuously growing longitudinal cohort of 1,421 patients with molecularly confirmed 22q11.2DS from 1992 to 2018. Most individuals are Caucasian and older than 8 years. The mean age at diagnosis was 3.9 years. The majority of patients (85%) had typical LCR22A-LCR22D deletions, and only 7% of these typical deletions were inherited from a parent harboring the deletion constitutionally. However, 6% of individuals harbored other nested deletions that would not be identified by traditional 22q11.2 FISH, thus requiring an orthogonal technology to diagnose. Major medical problems included immune dysfunction or allergies (77%), palatal abnormalities (67%), congenital heart disease (64%), gastrointestinal difficulties (65%), endocrine dysfunction (>50%), scoliosis (50%), renal anomalies (16%), and airway abnormalities. Median full-scale intelligence quotient was 76, with no significant difference between individuals with and without congenital heart disease or hypocalcemia. Characteristic dysmorphic facial features were present in most individuals, but dermatoglyphic patterns of our cohort are similar to normal controls. This is the largest longitudinal study of patients with 22q11.2DS, helping to further describe the condition and aid in diagnosis and management. Further surveillance will likely elucidate additional clinically relevant findings as they age.

Intermediate-Term Followup of Proximal Hypospadias Repair Reveals High Complication Rate.

PURPOSE: Results following distal hypospadias repair are favorable. Grouping proximal and distal hypospadias repair artificially increases the perceived success rate of proximal hypospadias. We identified our complication rate of proximal hypospadias repair and hypothesized a higher complication rate for 1-stage repair. MATERIALS AND METHODS: We retrospectively reviewed the records of consecutive boys who underwent proximal hypospadias from 2007 to 2014. Proximal hypospadias was defined as a urethral meatus location at or more proximal than the penoscrotal junction after penile degloving. We further stratified boys into those with planned 1-stage vs 2-stage repair. Univariate and Cox regression analyses were performed to assess associations with covariates and compare time to the first complication, respectively. RESULTS: A total of 167 boys met study inclusion criteria. Median followup was 31.7 months for 1-stage repair in 86 patients and staged repair in 81. The overall complication rate was 56%. Complications developed in 53 of 86 1-stage (62%) vs 40 of 81 staged (49%) repairs (p = 0.11). The number of unplanned procedures per patient was higher in the 1-stage than in the staged group (0.99 vs 0.69, p = 0.06), as was the number of patients who had at least 2 complications (29 of 86 or 33% vs 13 of 81 or 16%, p = 0.03). Cox regression showed no difference in time to the first complication for staged compared to 1-stage repair (HR 0.77, 95% CI 0.43-1.39). CONCLUSIONS: Our 56% complication rate of proximal hypospadias warrants further long-term patient followup. More patients in the 1-stage group experienced at least 2 complications. However, when complications developed, they developed no differently in the 2 groups.

Genomic copy number variation association study in Caucasian patients with nonsyndromic cryptorchidism.

BACKGROUND: Copy number variation (CNV) is a potential contributing factor to many genetic diseases. Here we investigated the potential association of CNV with nonsyndromic cryptorchidism, the most common male congenital genitourinary defect, in a Caucasian population. METHODS: Genome wide genotyping were performed in 559 cases and 1772 controls (Group 1) using Illumina HumanHap550 v1, HumanHap550 v3 or Human610-Quad platforms and in 353 cases and 1149 controls (Group 2) using the Illumina Human OmniExpress 12v1 or Human OmniExpress 12v1-1. Signal intensity data including log R ratio (LRR) and B allele frequency (BAF) for each single nucleotide polymorphism (SNP) were used for CNV detection using PennCNV software. After sample quality control, gene- and CNV-based association tests were performed using cleaned data from Group 1 (493 cases and 1586 controls) and Group 2 (307 cases and 1102 controls) using ParseCNV software. Meta-analysis was performed using gene-based test results as input to identify significant genes, and CNVs in or around significant genes were identified in CNV-based association test results. Called CNVs passing quality control and signal intensity visualization examination were considered for validation using TaqMan CNV assays and QuantStudio® 3D Digital PCR System. RESULTS: The meta-analysis identified 373 genome wide significant (p < 5X10-4) genes/loci including 49 genes/loci with deletions and 324 with duplications. Among them, 17 genes with deletion and 1 gene with duplication were identified in CNV-based association results in both Group 1 and Group 2. Only 2 genes (NUCB2 and UPF2) containing deletions passed CNV quality control in both groups and signal intensity visualization examination, but laboratory validation failed to verify these deletions. CONCLUSIONS: Our data do not support that structural variation is a major cause of nonsyndromic cryptorchidism.

Evaluation and Management of the Adolescent Varicocele.

PURPOSE: Varicocele is one of the most common genital conditions referred to pediatric urologists. Most adolescents with varicocele are asymptomatic and their fertility future (and surgery benefit) is largely unknown. This review assesses varicocele evaluation, management and indications for repair, as well as types and success of varicocelectomy. MATERIALS AND METHODS: A systematic literature review was performed on Embase™, PubMed® and Google Scholar™ for adolescent varicocele. Original research articles and relevant reviews were examined, and a synopsis of these data was generated for a comprehensive review of clinical adolescent varicocele management. RESULTS: The prevalence of adolescent varicocele is similar to the adult population. While ultrasound is the most sensitive method for determining testicular volumes, orchidometer measurement may be adequate to gauge significant discordance. Significant hypotrophy of the affected testis with poor total testicular volume may indicate a testis at risk and warrant surgical repair. Similar findings have been noted with an associated high peak retrograde venous flow. Testicular hypotrophy often resolves following surgery but may also improve spontaneously if followed through adolescence. Continued scrotal pain despite adequate support or serial abnormal semen analysis in Tanner stage V boys is an indication for varicocelectomy. Artery and lymphatic sparing techniques (microscopic subinguinal or laparoscopic) are associated with the lowest risk of recurrence and complications. CONCLUSIONS: Overtreatment and under treatment are medically and financially costly. Abnormal serial semen analysis with or without testicular hypotrophy is an indication for varicocele repair. If observation remains the treatment, followup with an adult urologist should be encouraged until paternity is achieved.

Histology of Testicular Biopsies Obtained for Experimental Fertility Preservation Protocol in Boys with Cancer.

PURPOSE: Cryopreservation of testicular tissue with subsequent reimplantation after therapy has the potential to preserve fertility for prepubertal boys with cancer. We present the histology and feasibility of testicular tissue procurement for this novel approach. MATERIALS AND METHODS: We performed a prospective cohort study of boys at significant risk for treatment associated gonadotoxicity who were eligible for an experimental research protocol between 2008 and 2011. Open testicular biopsy was performed while the patients were anesthetized for another treatment related procedure. Half of the specimen was reserved for cryopreservation, while the other half was used for research purposes. Semithin sections of the biopsy specimens were evaluated for histological features and compared to age adjusted reference values. RESULTS: A total of 34 boys underwent biopsy between March 2008 and October 2011. Of the patients 29 had solid tumors and 5 underwent hematopoietic stem cell transplantation for benign disease. A total of 27 patients had adequate tissue for histological analysis. Median patient age was 8.7 years (IQR 2.2 to 11.5). All children had either normal (81.5% of patients) or increased (18.5%) numbers of germ cells per tubule for their age. However, 5 of 26 patients (19%) older than 6 months had no evidence of adult dark spermatogonia and 9 of 16 (56%) older than 6 years had no evidence of primary spermatocytes on biopsy, which would be expected based on age norms. These findings are suggestive of abnormal germ cell maturation. CONCLUSIONS: The preliminary histological findings of abnormal spermatogenesis maturation in the testes of prepubertal boys with cancer warrants further investigation.

Phenotype specific association of the TGFBR3 locus with nonsyndromic cryptorchidism.

PURPOSE: Based on a genome-wide association study of testicular dysgenesis syndrome showing a possible association with TGFBR3, we analyzed data from a larger, phenotypically restricted cryptorchidism population for potential replication of this signal. MATERIALS AND METHODS: We excluded samples based on strict quality control criteria, leaving 844 cases and 2,718 controls of European ancestry that were analyzed in 2 separate groups based on genotyping platform (ie Illumina® HumanHap550, version 1 or 3, or Human610-Quad, version 1 BeadChip in group 1 and Human OmniExpress 12, version 1 BeadChip platform in group 2). Analyses included genotype imputation at the TGFBR3 locus, association analysis of imputed data with correction for population substructure, subsequent meta-analysis of data for groups 1 and 2, and selective genotyping of independent cases (330) and controls (324) for replication. We also measured Tgfbr3 mRNA levels and performed TGFBR3/betaglycan immunostaining in rat fetal gubernaculum. RESULTS: We identified suggestive (p ≤ 1× 10(-4)) association of markers in/near TGFBR3, including rs9661103 (OR 1.40; 95% CI 1.20, 1.64; p = 2.71 × 10(-5)) and rs10782968 (OR 1.58; 95% CI 1.26, 1.98; p = 9.36 × 10(-5)) in groups 1 and 2, respectively. In subgroup analyses we observed strongest association of rs17576372 (OR 1.42; 95% CI 1.24, 1.60; p = 1.67 × 10(-4)) with proximal and rs11165059 (OR 1.32; 95% CI 1.15, 1.38; p = 9.42 × 10(-4)) with distal testis position, signals in strong linkage disequilibrium with rs9661103 and rs10782968, respectively. Association of the prior genome-wide association study signal (rs12082710) was marginal (OR 1.13; 95% CI 0.99, 1.28; p = 0.09 for group 1), and we were unable to replicate signals in our independent cohort. Tgfbr3/betaglycan was differentially expressed in wild-type and cryptorchid rat fetal gubernaculum. CONCLUSIONS: These data suggest complex or phenotype specific association of cryptorchidism with TGFBR3 and the gubernaculum as a potential target of TGFß signaling.

Pathway analysis supports association of nonsyndromic cryptorchidism with genetic loci linked to cytoskeleton-dependent functions.

STUDY QUESTION: What are the genetic loci that increase susceptibility to nonsyndromic cryptorchidism, or undescended testis? SUMMARY ANSWER: A genome-wide association study (GWAS) suggests that susceptibility to cryptorchidism is heterogeneous, with a subset of suggestive signals linked to cytoskeleton-dependent functions and syndromic forms of the disease. WHAT IS KNOWN ALREADY: Population studies suggest moderate genetic risk of cryptorchidism and possible maternal and environmental contributions to risk. Previous candidate gene analyses have failed to identify a major associated locus, although variants in insulin-like 3 (INSL3), relaxin/insulin-like family peptide receptor 2 (RXFP2) and other hormonal pathway genes may increase risk in a small percentage of patients. STUDY DESIGN, SIZE, DURATION: This is a case-control GWAS of 844 boys with nonsyndromic cryptorchidism and 2718 control subjects without syndromes or genital anomalies, all of European ancestry. PARTICIPANTS/MATERIALS, SETTING, METHODS: All boys with cryptorchidism were diagnosed and treated by a pediatric specialist. In the discovery phase, DNA was extracted from tissue or blood samples and genotyping performed using the Illumina HumanHap550 and Human610-Quad (Group 1) or OmniExpress (Group 2) platform. We imputed genotypes genome-wide, and combined single marker association results in meta-analyses for all cases and for secondary subphenotype analyses based on testis position, laterality and age, and defined genome-wide significance as P = 7 × 10(-9) to correct for multiple testing. Selected markers were genotyped in an independent replication group of European cases (n = 298) and controls (n = 324). We used several bioinformatics tools to analyze top (P < 10(-5)) and suggestive (P < 10(-3)) signals for significant enrichment of signaling pathways, cellular functions and custom gene lists after multiple testing correction. MAIN RESULTS AND THE ROLE OF CHANCE: In the full analysis, we identified 20 top loci, none reaching genome-wide significance, but one passing this threshold in a subphenotype analysis of proximal testis position (rs55867206, near SH3PXD2B, odds ratio = 2.2 (95% confidence interval 1.7, 2.9), P = 2 × 10(-9)). An additional 127 top loci emerged in at least one secondary analysis, particularly of more severe phenotypes. Cytoskeleton-dependent molecular and cellular functions were prevalent in pathway analysis of suggestive signals, and may implicate loci encoding cytoskeletal proteins that participate in androgen receptor signaling. Genes linked to human syndromic cryptorchidism, including hypogonadotropic hypogonadism, and to hormone-responsive and/or differentially expressed genes in normal and cryptorchid rat gubernaculum, were also significantly overrepresented. No tested marker showed significant replication in an independent population. The results suggest heterogeneous, multilocus and potentially multifactorial susceptibility to nonsyndromic cryptorchidism. LIMITATIONS, REASONS FOR CAUTION: The present study failed to identify genome-wide significant markers associated with cryptorchidism that could be replicated in an independent population, so further studies are required to define true positive signals among suggestive loci. WIDER IMPLICATIONS OF THE FINDINGS: As the only GWAS to date of nonsyndromic cryptorchidism, these data will provide a basis for future efforts to understand genetic susceptibility to this common reproductive anomaly and the potential for additive risk from environmental exposures. STUDY FUNDING/COMPETING INTERESTS: This work was supported by R01HD060769 (the Eunice Kennedy Shriver National Institute for Child Health and Human Development (NICHD)), P20RR20173 (the National Center for Research Resources (NCRR), currently P20GM103464 from the National Institute of General Medical Sciences (NIGMS)), an Institute Development Fund to the Center for Applied Genomics at The Children's Hospital of Philadelphia, and Nemours Biomedical Research. The authors have no competing interests to declare.