BACKGROUND: It has been suggested that cryptorchidism and hypospadias may be the result of a common pathologic pathway that causes testicular dysgenesis during fetal life. To address the potential heritability of this pathway, we specifically examined to what extent a family history of cryptorchidism increases the risk of developing hypospadias and vice versa. METHODS: By using Danish health registers, we identified 27,762 boys diagnosed with cryptorchidism and 4832 boys diagnosed with hypospadias in a cohort of 1,018,517 boys born during 1977-2005. Using binomial log-linear regression, we estimated risk ratios of cryptorchidism and hypospadias in male twin pairs and first-, second-, and third-degree relatives with a family history of hypospadias and cryptorchidism, respectively. RESULTS: After adjusting for birth period and personal hypospadias/cryptorchidism status, there was little evidence of increased risk of cryptorchidism given a family history of hypospadias, and vice versa. However, cryptorchidism and hypospadias was associated on an individual level. CONCLUSION: We found no persuasive evidence that a family history of hypospadias increases the risk of cryptorchidism and vice versa. Thus, we found no support for shared heritability of hypospadias and cryptorchidism.
BACKGROUND: It has been suggested that cryptorchidism and hypospadias may be the result of a common pathologic pathway that causes testicular dysgenesis during fetal life. To address the potential heritability of this pathway, we specifically examined to what extent a family history of cryptorchidism increases the risk of developing hypospadias and vice versa. METHODS: By using Danish health registers, we identified 27,762 boys diagnosed with cryptorchidism and 4832 boys diagnosed with hypospadias in a cohort of 1,018,517 boys born during 1977-2005. Using binomial log-linear regression, we estimated risk ratios of cryptorchidism and hypospadias in male twin pairs and first-, second-, and third-degree relatives with a family history of hypospadias and cryptorchidism, respectively. RESULTS: After adjusting for birth period and personal hypospadias/cryptorchidism status, there was little evidence of increased risk of cryptorchidism given a family history of hypospadias, and vice versa. However, cryptorchidism and hypospadias was associated on an individual level. CONCLUSION: We found no persuasive evidence that a family history of hypospadias increases the risk of cryptorchidism and vice versa. Thus, we found no support for shared heritability of hypospadias and cryptorchidism.