What causes familial hypospadias?
In most cases, the cause of hypospadias is unknown. It is believed to occur because of multiple genetic factors in combination with environmental factors during pregnancy, rather than due to a single genetic cause.
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Are there any risk factors that increase my chance of having a boy with familial hypospadias?
In recent years, several factors have been associated with an increased chance to have a baby boy with hypospadias. Several of these factors have a strong association with hypospadias, while others have a weaker or more inconsistent association. The stronger factors include:
- The use of certain hormones, such estrogen or progestin, during pregnancy by the mother
- Babies who are smaller than expected for the timing of the pregnancy (sometimes called intrauterine growth restriction or IUGR), or a low birthweight
- Placental insufficiency, which is when the placenta is not providing the baby with enough nutrients or oxygen because the placenta did not develop properly or was damaged
- High blood pressure in the mother during pregnancy, including maternal hypertension and pre-eclampsia
Other factors have not been consistently linked to hypospadias in different studies. These include:
- Mothers who are 35 years or older when they become pregnant
- Mothers who are obese
- Mothers who already have diabetes when they become pregnant (but not gestational diabetes, which is diabetes that first develops during pregnancy)
- The use of fertility treatments and assisted reproductive technology to become pregnant; however, some treatments (such as intracytoplasmic sperm injection or ICSI) are more strongly associated with hypospadias, while other treatments (such as in vitro fertilization or IVF), are not well associated with hypospadias
It is important to remember that most mothers with any of the above risk factors have baby boys with normal genitalia and no hypospadias.
- Carmichael SL, Shaw GM, Laurent C, Olney RS, Lammer EJ, and the National Birth Defects Prevention Study. Maternal reproductive and demographic characteristics as risk factors for hypospadias. Paediatr Perinat Epidemiol. 2007; 21: 210-218.
- Reefhuis J, Honein MA, Schieve LA, Correa A, Hobbs CA, Rasmussen SA, and the National Birth Defects Prevention Study. Assisted reproductive technology and major structural birth defects in the United States. Human Rep. 2009; 24:360-366
- Carmichael SL, Shaw GM, Laurent C, Croughan MS, Olney RS, Lammer EJ. Maternal progestin intake and risk of hypospadias. Arch Pediatr Adolesc Med. 2005;159: 957-962
- van der Zanden LFM, van Rooij IALM, Feitz WFJ, Franke B, Knoers NVAM, and Roeleveld N. Aetiology of hypospadias: a systematic review of genes and environment. Hum Reprod Update. 2012; 18(3):260-283.
Are there any genes involved with familial hypospadias?
It is important to remember that scientists believe hypospadias is caused by a combination of both genetic and environmental factors. In most cases, there is nothing a parent could have done or could have not done to prevent it. That being said, in rare cases, a genetic change, such as one in the MAMLD1 gene, or changes in a group of genes may play a larger role in causing hypospadias and increase the chance for a baby to have familial hypospadias.
- Thai, H. T. T., Soderhall, C., Lagerstedt, K., Omrani, M. D., Frisen, L., Lundin, J., Kockum, I., Nordenskjold, A. A new susceptibility locus for hypospadias on chromosome 7q32.2-q36.1. Hum. Genet. 124: 155-160, 2008