Risk Factors for Hypospadias: A Case Control Study

Abstract

Despite being one of the most common congenital defects in boys, the etiology of hypospadias remains largely unknown. In this study we evaluated a spectrum of potential risk factors for hypospadias in which we focused on both paternal and maternal factors and chromosomal aberrations. Cases were selected from the Genetic Clinic, Medical Research Institute, University of Alexandria. A total of 176 cases with hypospadias were included in this study, and a matching control group of normal 300 boys for the association study. All cases were subjected to detailed family, pregnancy, genetic histories, clinical examination, and pedigree study. Chromosome analysis was performed using peripheral blood lymphocyte cultures by trypsin G-banding technique. Hormonal assays, abdominal and pelvic ultrasound were carried out according to case presentation. Both parents of cases and the control group completed written questionnaires. Abnormal karyotyes were detected in 23 cases (13.07%) associated with other anomalies, sex chromosome abnormalities were present in 69.56% and autosomal aberrations in 30.43%. Patients with chromosomal abnormalities were excluded from the association study. Logistic regression analysis was used to assess the independent contribution of different factors to the risk of hypospadias. Our data did not support an association with increased parental age. The most profound result was the increased risk of hypospadias for boys with positive family history (n=23; OR=26.36; 95% CI: 5.90-164.23). Strong indications for an increased risk of hypospadias were also found with low birth weight (n=45; OR=13.47; 95% CI=6.09-30.70), preterm birth (n=6; OR=12.20; 95% CI=1.45-271.47), twin or triplet pregnancy (n=4; OR=8.03; 95% CI=0.84-190.23), and when mothers had preeclampsia (n=16; OR=11.56; 95% CI=3.11-50.77). Associations with pregnancy achieved with fertility treatment, and mother used iron supplements were also found. In conclusion, routine karyotype screening permits the diagnosis of chromosomal anomalies especially in those with the most severe forms of hypospadias and additional anomalies. Several risk factors have been identified for hypospadias which support the idea that genetic predisposition, placental insufficiency, and substances that interfere with natural hormones before conception or during fetal development play a role in the etiology of hypospadias.