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Renal Agenesis

Birth Defects Risk Factor Series

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Renal agenesis is the absence of one or both of the kidneys. Bilateral renal agenesis is invariably fatal. Unilateral renal agenesis may be asymptomatic and is often incidentally diagnosed by abdominal ultrasound or computed tomography (CT) scan secondary to another condition. In infants with unilateral renal agenesis, the remaining kidney may be enlarged, and there is increased risk of problems with the remaining kidney. The metanephric buds begin to develop into kidneys in the fifth week of gestation. If the metanephric buds fail to develop, renal agenesis results. Often, what appears to be unilateral renal agenesis is actually aplasia of one kidney which had involuted after birth (Hiraoka 2001). Either the left or the right kidney is as likely to be absent (Dursan 2005).

Renal agenesis has been associated with such chromosomal abnormalities as trisomy 21, trisomy 22, trisomy 7, trisomy 10, 45,X mosaicism, and 22q11 microdeletion (Bianchi et al., 2000), as well as congenital hearing loss and double uterus in females (Huang 2001).

Fetal deaths have been reported to account for 10-33% of cases of renal agenesis (Bianchi et al., 2000; Riley et al., 1998; Cunniff et al., 1994). Renal agenesis can be prenatally detected by ultrasound (Bianchi et al., 2000). Thus, in regions where elective termination is allowed, prenatal diagnosis and elective termination may reduce the birth prevalence of renal agenesis (Riley et al., 1998; Sipek et al., 1997; Chi et al., 1995; Papp et al., 1995; Stoll et al., 1995a; Stoll et al., 1995b; Cunniff et al., 1994; Julian-Reynier et al., 1994; Stoll et al., 1992).


One investigation reported no significant association between race/ethnicity and renal agenesis risk (Leck and Lancashire, 1995). Another study observed no significant difference in risk of renal agenesis/dysgenesis in infants born to Vietnamese women compared to infants born to non-Hispanic white women in California (Shaw et al., 2002). Hawaiian residents of Japanese descent appear to have higher rates of offspring with renal agenesis than their white counterparts (Forrester 2006). An investigation in Colorado found increased risk of renal agenesis among African-Americans when compared to whites (Parikh et al., 2002). The study did not find any association between renal agenesis and Hispanic ethnicity.

Place of residence within a country does not appear to influence risk of renal agenesis (Stroup et al., 1990). One investigation failed to identify any association between renal agenesis and altitude (Castilla et al., 1999).

One study reported a secular trend for bilateral renal agenesis, with rates for the defect increasing over time (CDC, 1998). However, this increase may have been due to increased ascertainment of other renal anomalies, such as renal dysgenesis. Moreover, other studies reported no secular trends for either bilateral or unilateral renal agenesis (Chi et al., 1995; Stroup et al., 1990; Wilson and Baird, 1985).

One investigation reported seasonal differences in renal agenesis rates (Bound et al., 1989), while another study reported no such association (Stroup et al., 1990).

Bilateral renal agenesis risk is affected by sex, with the defect being more common among males (Lary and Paulozzi, 2001; Bianchi et al., 2000; Riley et al., 1998; Stoll et al., 1990; Stroup et al., 1990; Wilson and Baird, 1985, Potter 1965). Unilateral renal agenesis has been reported to be equally common among the sexes (Wilson and Baird, 1985). A higher proportion of renal agenesis has been reported among males (Parikh et al., 2002).

There is no association between renal agenesis risk and either maternal age (Bianchi et al., 2000; Hollier et al., 2000) or paternal age (McIntosh et al., 1995). However, one investigation reported a higher proportion of renal agenesis with younger maternal age, although the results were not statistically significant (Parikh et al., 2002). Risk of renal agenesis or dysgenesis has been reported to increase with lower birth weight (Parikh et al., 2002; Riley et al., 1998; Mili et al., 1991) and prematurity (Rasmussen et al., 2001). The renal defect has been associated with intrauterine growth retardation (Khoury et al., 1988). Renal agenesis is more common among multiple gestation pregnancies (Bianchi et al., 2000; Mastroiacovo et al., 1998; Riley et al., 1998; Kallen, 1986).


Renal agenesis has been associated with lower maternal education (Parikh et al., 2002).

Renal agenesis has not been associated with maternal hyperthyroidism or hypothyroidism (Khoury et al., 1989). The literature on the relationship between renal agenesis and maternal diabetes is mixed with several reporting an association (Nielsen 2004, Parikh et al., 2002; Ramos-Arroyo et al., 1992) while others do not (Moore et al., 2000; Becerra et al., 1990). One study found that high body mass index among women with gestational diabetes was associated with the occurrence of major renal/urinary defects (Garcia-Patterson 2004) , while another found higher risk for renal defects (several types) and a women who had higher body mass index along with a history of fertility problems (Honein 2003). Maternal hypertension does not appear to be associated with renal agenesis (Parikh et al., 2002). Cases with renal agenesis are more likely to have lower maternal weight gain during pregnancy (Parikh et al., 2002). Another study reported no association between renal agenesis and maternal obesity (Moore et al., 2000).

One study failed to identify any association between renal agenesis/hypoplasia and maternal flu-like illness, with or without fever or medication (Abe 2003).

Studies have reported increased risk of renal agenesis or dysgenesis with maternal alcohol consumption (Parikh et al., 2002; Moore et al., 1997). Several studies found increased risk of renal agenesis with maternal smoking, although the increase was not statistically significant (Parikh et al., 2002; Honein et al., 2001; Kallen, 1997; Shiono et al., 1986). Other investigations found no association between maternal use of cephalosporin antibiotics, ampicillin, or the benzodiazepines nitrazepam, medazepam, tofisopam, alprazolum, and clonazepam during pregnancy and renal agenesis (Eros et al., 2002; Czeizel et al., 2001a; Czeizel et al., 2001b).

One study found that maternal use of folic acid supplements at any time during pregnancy does not appear to affect risk of renal agenesis (Czeizel et al., 1996), however, rates of this condition have decreased in some states following folic acid fortification of the U.S. grain supply (Canfield 2005).

No association has been found between proximity to municipal hazardous waste incinerators and renal agenesis, although the risk for renal dysplasia was higher (Cordier 2003).

One study found that infants conceived postwar and born to male Gulf War veterans were much more likely to have renal agenesis/hypoplasia than those conceived prewar (Araneta 2003).


Birth prevalence in the United States for renal agenesis/hypoplasia ranges between 0.30 and 9.61 per 10,000 live births ( National Center on Birth Defects and Developmental Disabilities 2006). The rate in Texas among 1999-2003 deliveries was 5.28 cases per 10,000 live births (includes atresia or stenosis of the large intestine) (Texas Department of State Health Services 2006). Differences in prevalence may be due to differences in case inclusion criteria.


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Please Note: The primary purpose of this report is to provide background necessary for conducting cluster investigations. It summarizes literature about risk factors associated with this defect. The strengths and limitations of each reference were not critically examined prior to inclusion in this report. Consumers and professionals using this information are advised to consult the references given for more in-depth information. 

This report is for information purposes only and is not intended to diagnose, cure, mitigate, treat, or prevent disease or other conditions and is not intended to provide a determination or assessment of the state of health. Individuals affected by this condition should consult their physician and when appropriate, seek genetic counseling.

For more information:

Birth Defects Epidemiology and Surveillance
Texas Department of State Health Services
1100 W. 49th Street, Austin, Texas 78756
512-776-7232 Fax 512-776-7330

Document E58-10957                    Revised July 2007

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Last updated February 10, 2012