Congenital genitourinary tract abnormalities following cocaine exposure in utero

A Primer on Congenital Anomalies of the Kidneys and Urinary Tracts (CAKUT)

Congenital anomalies of the kidneys and urinary tracts (CAKUT) are disorders caused by defects in the development of the kidneys and their outflow tracts. The formation of the kidneys begins at week 3 and nephrogenesis continues until week 36, therefore, the kidneys and outflow tracts are susceptible to environmental risk factors that perturb development throughout gestation. Many genes have been implicated in kidney and outflow tract development, and mutations have been identified in patients with CAKUT. In severe cases of CAKUT, when the kidneys do not form, the fetus will not survive. However, in less severe cases, the baby can survive with combined kidney and outflow tract defects or they may only be identified in adulthood. In this review, we will cover the clinical presentation of CAKUT, its epidemiology, and its long-term outcomes. We will then discuss risk factors for CAKUT, including genetic and environmental contributions. Although severe CAKUT is rare, low nephron number is a much more common disorder with its effect on kidney function increasingly apparent as a person ages. Low nephron number appears to arise by the same mechanisms as CAKUT, but it differs in terms of the magnitude of the insult and the timing of when it occurs during gestation. By understanding the causes of CAKUT and low nephron number, we can begin to identify preventive treatments and establish clinical guidelines for how these patients should be followed.

Genetic Basis of Ureterocele

Congenital anomalies of the kidney and urinary tract (CAKUT) form a group of heterogeneous disorders that affect the kidneys, ureters and bladder, with frequent asynchronous presentations and multiple CAKUT associations in the same individual. Urinary tract formation is a complex process, dependent of the interaction of multiple genes and their sub-product. The same genic alterations can lead to different molecular expressions and different morphological anomalies. The ureterocele is a cystic dilation of the distal intramural ureter, resulting in obstruction of urine flow, dilation of the ureter and renal pelvis and loss of renal function. Two key steps in the urinary tract ontogenesis may be related to ureterocele development: formation and migration of the ureteric bud and its incorporation in the bladder. This review aims to describe the morphological, cellular and biochemical steps, as well as the genes involved in the occurrence of this anomaly.

Similar causes of various reproductive disorders in early life

During the past few decades, scientific evidence has been accumulated concerning the possible adverse effects of the exposure to environmental chemicals on the well-being of wildlife and human populations. One large and growing group of such compounds of anthropogenic or natural origin is referred to as endocrine-disrupting chemicals (EDCs), due to their deleterious action on the endocrine system. This concern was first focused on the control of reproductive function particularly in males, but has later been expanded to include all possible endocrine functions. The present review describes the underlying physiology behind the cascade of developmental events that occur during sexual differentiation of males and the specific role of androgen in the masculinization process and proper organogenesis of the external male genitalia. The impact of the genetic background, environmental exposures and lifestyle factors in the etiology of hypospadias, cryptorchidism and testicular cancer are reviewed and the possible role of EDCs in the development of these reproductive disorders is discussed critically. Finally, the possible direct and programming effects of exposures in utero to widely use therapeutic compounds, environmental estrogens and other chemicals on the incidence of reproductive abnormalities and poor semen quality in humans are also highlighted.

Renal teratogens

In utero exposure to certain drugs early in pregnancy may adversely affect nephrogenesis. Exposure to drugs later in pregnancy may affect the renin-angiotensin system, which could have an impact on fetal or neonatal renal function. Reduction in nephron number and renal function could have adverse consequences for the child several years later. Data are limited on the information needed to guide decisions for patients and providers regarding the use of certain drugs in pregnancy. The study of drug nephroteratogenicity has not been systematized, a large, standardized, global approach is needed to evaluate the renal risks of in utero drug exposures.

Review of genetic and environmental factors leading to hypospadias

Hypospadias is one of the most common congenital malformations, affecting about 4-6 males per 1000 male births, and ranging in severity from a urethral meatus that is slightly off-center to a meatus in the perineal area. Over the past three decades its prevalence may have increased due to changes in reporting of mild cases and/or increased survival of low birth weight infants due to improved neonatal care. However, despite the increasing numbers of males with hypospadias, the overall etiology remains unclear and likely multifactorial in nature. The purpose of this review article is to provide a comprehensive overview of the various factors implicated in hypospadias etiology, including genetic and environmental factors. In addition, we list syndromes in which hypospadias is a relatively common association and delineate the areas that require further investigation in an effort to understand this condition.

Congenital anomalies of the kidney and urinary tract: a genetic disorder? Int J Nephrol. 2012;2012:909083. [PMID: 22685656 PMCID: PMC3363415 DOI: 10.1155/2012/909083]

Congenital anomalies of the kidney and urinary tract (CAKUTs) occur in 3–6 per 1000 live births, account for the most cases of pediatric end-stage kidney disease (ESKD), and predispose an individual to hypertension and cardiovascular disease throughout life. Although CAKUTs are a part of many known syndromes, only few single-candidate causative genes have been implicated so far in nonsyndromic cases of human CAKUT. Evidence from mouse models supports the hypothesis that non-syndromic human CAKUT may be caused by single-gene defects. Because increasing numbers of children with CAKUT are surviving to adulthood, better understanding of the molecular pathogenesis of CAKUT, development of new strategies aiming at prevention of CAKUT, preservation of renal function, and avoidance of associated cardiovascular morbidity are needed. In this paper, we will focus on the knowledge derived from the study of syndromic and non-syndromic forms of CAKUT in humans and mouse mutants to discuss the role of genetic, epigenetic, and in utero environmental factors in the pathogenesis of non-syndromic forms of CAKUT in children with particular emphasis on the genetic contributions to CAKUT.

Aetiology of hypospadias: a systematic review of genes and environment

BACKGROUND

Hypospadias is a common congenital malformation of the male external genitalia. Most cases have an unknown aetiology, which is probably a mix of monogenic and multifactorial forms, implicating both genes and environmental factors. This review summarizes current knowledge about the aetiology of hypospadias.

METHODS

Pubmed was used to identify studies on hypospadias aetiology published between January 1995 and February 2011. Reference lists of the selected manuscripts were also searched to identify additional studies, including those published before 1995.

RESULTS

The search provided 922 articles and 169 articles were selected for this review. Studies screening groups of patients with hypospadias for single gene defects found mutations in WT1, SF1, BMP4, BMP7, HOXA4, HOXB6, FGF8, FGFR2, AR, HSD3B2, SRD5A2, ATF3, MAMLD1, MID1 and BNC2. However, most investigators are convinced that single mutations do not cause the majority of isolated hypospadias cases. Indeed, associations were found with polymorphisms in FGF8, FGFR2, AR, HSD17B3, SRD5A2, ESR1, ESR2, ATF3, MAMLD1, DGKK, MID1, CYP1A1, GSTM1 and GSTT1. In addition, gene expression studies indentified CTGF, CYR61 and EGF as candidate genes. Environmental factors consistently implicated in hypospadias are low birthweight, maternal hypertension and pre-eclampsia, suggesting that placental insufficiency may play an important role in hypospadias aetiology. Exogenous endocrine-disrupting chemicals have the potential to induce hypospadias but it is unclear whether human exposure is high enough to exert this effect. Other environmental factors have also been associated with hypospadias but, for most, the results are inconsistent.

CONCLUSIONS

Although a number of contributors to the aetiology of hypospadias have been identified, the majority of risk factors remain unknown.

Genetics of congenital anomalies of the kidney and urinary tract

Congenital anomalies of the kidney and urinary tract (CAKUT) occur in 1 in 500 births and are a major cause of morbidity in children. Notably, CAKUT account for the most cases of pediatric end-stage renal disease and predispose the individual to hypertension and cardiovascular disease throughout life. Although some forms of CAKUT are a part of a syndrome or are associated with a positive family history, most cases of renal system anomalies are sporadic and isolated to the urinary tract. Broad phenotypic spectrum of CAKUT and variability in genotype-phenotype correlation indicate that pathogenesis of CAKUT is a complex process that depends on interplay of many factors. This review focuses on the genetic mechanisms (single-gene mutations, modifier genes) leading to renal system anomalies in humans and discusses emerging insights into the role of epigenetics, in utero environmental factors, and micro-RNAs (miRNAs) in the pathogenesis of CAKUT. Common gene networks that function in defined temporospatial fashion to orchestrate renal system morphogenesis are highlighted. Derangements in cellular, molecular, and morphogenetic mechanisms that direct normal renal system development are emphasized as a major cause of CAKUT. Integrated understanding of how morphogenetic process disruptions are linked to CAKUT will enable improved diagnosis, treatment, and prevention of congenital renal system anomalies and their consequences.

Genetics of renal hypoplasia: insights into the mechanisms controlling nephron endowment

Renal hypoplasia, defined as abnormally small kidneys with normal morphology and reduced nephron number, is a common cause of pediatric renal failure and adult-onset disease. Genetic studies performed in humans and mutant mice have implicated a number of critical genes, in utero environmental factors and molecular mechanisms that regulate nephron endowment and kidney size. Here, we review current knowledge regarding the genetic contributions to renal hypoplasia with particular emphasis on the mechanisms that control nephron endowment in humans and mice.

Infant race affects application of clinical guidelines when screening for drugs of abuse in newborns

BACKGROUND

Screening for illicit drugs in newborns has privacy, social, and legal risks for families of the infants. Established drug-screening criteria may be applied in a manner that considers nonproven risk factors such as race in addition to evidence-based factors.

OBJECTIVE

The goal of this study was to determine if race was used as a criterion for screening infants for intrauterine cocaine exposure. We hypothesized that infants of black mothers would be more likely to be screened regardless of whether they met the standard criteria for screening of our institution's NICU.

METHODS

We used the electronic medical records of newborn infants and their mothers to determine which mother-infant pairs had documented evidence of meeting the criteria for screening infants for prenatal exposure to illicit drugs set forth in the guidelines of our NICU. We then assessed the rates of drug screening to determine the strongest predictors of whether an infant would be screened.

RESULTS

We assessed 2121 mother-infant pairs. Infants born to black mothers were more likely than those born to white mothers to have screening performed whether they met screening criteria (35.1% vs 12.9%; P < .001) or did not (5.3% vs 1.2%; P < .001). In a logistic regression analysis, black race remained independently associated (odds ratio: 2.17 [95% confidence interval: 1.25-3.79]) with drug screening even when we controlled for our standard screening criteria and income, insurance status, and maternal education.

CONCLUSION

Providers seemed to have used race, in addition to recognized risk criteria, as a factor in deciding whether to screen an infant for maternal illicit drug use.

Maternal periconceptional illicit drug use and the risk of congenital malformations

BACKGROUND

In 2004, the Survey on Drug Use and Health showed that 5% of American women reported use of an illicit drug during pregnancy. The results of studies determining the association between periconceptional illicit drug use and birth defects have been inconsistent.

METHODS

We analyzed data from the National Birth Defects Prevention Study, a case-control study of major birth defects, and assessed all birth defects categories in which there were at least 250 interviewed case mothers. We included 10,241 infants with major congenital malformations (case infants) and 4,967 infants without major congenital malformations (control infants) born between 1997 and 2003 for whom there was a completed maternal interview with detailed information on prenatal illicit drug use and potential confounders. We used multivariable logistic regression to estimate the associations between cannabis, cocaine, and stimulant use in the month before pregnancy or during the first trimester (periconceptional period) and the occurrence of selected birth defects.

RESULTS

In the periconceptional period, 5% of the 15,208 mothers reported any use of illicit drugs. We did not find associations between illicit drug use and most of the 20 eligible categories of congenital malformations. Periconceptional cannabis use seemed to be associated with an increased risk of anencephaly (adjusted odds ratio = 1.7; 95% confidence interval = 0.9-3.4), whereas cocaine use in the periconceptional period was associated with the risk of cleft palate (2.5; 1.1-5.4).

CONCLUSIONS

There were very few suggestions of positive associations between periconceptional illicit drug use and the 20 birth defects categories.

Genetic syndromes and prenatally detected renal anomalies

Renal anomalies are frequently detected on the routine second trimester scan offered to all pregnant women in the UK. These anomalies may be isolated but can also be associated with other congenital anomalies. Many combinations of ultrasound scan findings constitute recognised genetic entities. Knowledge of these conditions is essential for adequate management of the pregnancy and subsequent balanced parental counselling. This short review discusses the common genetic syndromes associated with the renal abnormalities identified on the antenatal ultrasound scan, and also provides an overview of renal symptoms in chromosome imbalances and after teratogenic influences.

Risk of selected birth defects with prenatal illicit drug use, Hawaii, 1986-2002

The literature on the association between prenatal illicit drug use and birth defects is inconsistent. The objective of this study was to determine the risk of a variety of birth defects with prenatal illicit drug use. Data were derived from an active, population-based adverse pregnancy outcome registry. Cases were all infants and fetuses with any of 54 selected birth defects delivered during 1986-2002. The prenatal methamphetamine, cocaine, or marijuana use rates were calculated for each birth defect and compared to the prenatal use rates among all deliveries. Among all deliveries, the prenatal use rate was 0.52% for methamphetamine, 0.18% for cocaine, and 0.26% for marijuana. Methamphetamine rates were significantly higher than expected for 14 (26%) of the birth defects. Cocaine rates were significantly higher than expected for 13 (24%) of the birth defects. Marijuana rates were significantly higher than expected for 21 (39%) of the birth defects. Increased risk for the three drugs occurred predominantly among birth defects associated with the central nervous system, cardiovascular system, oral clefts, and limbs. There was also increased risk of marijuana use among a variety of birth defects associated with the gastrointestinal system. Prenatal uses of methamphetamine, cocaine, and marijuana are all associated with increased risk of a variety of birth defects. The affected birth defects are primarily associated with particular organ systems.

Endocrine abnormalities in boys with hypospadias

The multifactorial etiology of hypospadias is becoming more clearly defined with ongoing investigation. Endogenous endocrine abnormalities identified so far include testosterone biosynthesis defects, 5alpha-reductase type 2 mutations, and androgen receptor mutations (the rarest cause, even in cases of severe hypospadias). Other significant risk factors include IVF (because of progesterone administration or endocrine abnormalities associated with infertility) and environmental agents that can potentially cause testicular dysgenesis, disrupt the male androgen axis, and disturb normal male genital embryology (Table 6). [table; see text] It also seems that the incidence of hypospadias is increasing, both in the United States and in Europe--which may be due to better medical care for those with genital abnormalities and/or infertility problems, as well as environmental endocrine disruptors. Hypospadias is a physical manifestation that may be a consequence of numerous physiological aberrations, and our ability to understand and to potentially prevent this congenital malformation will require a significant amount of additional work. Our challenge for the future remains to identify the various etiologies, provide prenatal counseling for affected families with a history of hypospadias, and minimize or eliminate exposure to environmental agents that may contribute to this problem. Perhaps one day we will be able to offer prenatal therapy to prevent hypospadias when the risk for this birth defect seems high. How might this be possible? Consider the modern management of a family with a child born with the adrenogenital syndrome, another endocrine derangement that can cause abnormal genital development. In this situation, dexamethasone can be administered to the mother in subsequent pregnancies to prevent fetal virilization until the sex of the fetus can be determined or adrenal enzyme mutations can be excluded. Perhaps in the future a similar approach will be taken for those families with strong risk factors for hypospadias.

Fetal bilateral renal agenesis, phocomelia, and single umbilical artery associated with cocaine abuse in early pregnancy

BACKGROUND

Maternal cocaine abuse in pregnancy is associated with complications such as intrauterine growth retardation, abruptio placentae, and preterm delivery.

CASE

We report what is, to our knowledge, the first published observation of fetal bilateral renal agenesis associated with a vascular disruption syndrome comprising upper limb reduction defect and a single umbilical artery following maternal cocaine abuse in early pregnancy.

CONCLUSIONS

This constellation in a fetus aborted at 18 weeks extends the spectrum of complications possibly associated with cocaine abuse in pregnancy.

Maternal febrile illnesses, medication use, and the risk of congenital renal anomalies

BACKGROUND

Renal anomalies occur in about three infants per 1000 live births and have been associated with several environmental risk factors. Researchers have yet to assess the effect of maternal febrile illnesses on renal anomalies, even though febrile illnesses have been associated with other birth defects. Our objective was to determine whether maternal illness, fever, or medication use during the first trimester of pregnancy is associated with the occurrence of renal anomalies.

METHODS

In this population-based case-control study, we evaluated 192 infants with renal anomalies (renal agenesis [n = 44], obstructive defects [n = 134], and renal duplication defects [n = 14]) and 3029 infant without birth defects, all of whom were born in metropolitan Atlanta, Georgia, from 1968 through 1980. Maternal illness was defined as reported flu-like illness and/or episodic illness during the first trimester.

RESULTS

Our adjusted multivariate analyses showed that among the 192 case-infants, 38 had mothers with an illness (adjusted odds ratio [AOR], 1.71; 95% confidence interval [CI], 1.15-2.52), 20 had mothers who reported a fever (AOR, 1.80; 95% CI, 1.07-3.02) and 26 had mothers who reported taking medication (AOR, 1.69; 95% CI, 1.07-2.68). Fifteen mothers reported a fever and medication use (AOR, 1.90; 95% CI, 1.05-3.45). Nonprescription aspirin-containing medication use showed the strongest association (AOR, 3.45; 95% CI, 1.36-8.75) with renal anomalies.

CONCLUSIONS

Our data suggest that maternal exposure to illness, fever, and medication (particularly aspirin) may increase the risk of congenital renal anomalies.

Hypospadias and early gestation growth restriction in infants

OBJECTIVE

There has been a major increase in the incidence of hypospadias in infants in the 1990s, but the risk factors are not known. Although there are scattered reports in the literature regarding the association of low birth weight and hypospadias, this has not been systematically studied. The objective of this study was to determine the association between early gestation intrauterine growth and hypospadias.

METHODS

A retrospective review of 13 years of admissions to 2 tertiary care neonatal intensive care units (NICUs) in Connecticut (1987--2000) showed that 112 (1.66%) of 6746 male infants had any degree of hypospadias. Of these, 8 were part of a genetic syndrome and were excluded. A retrospective cohort analysis of these 6738 infants was performed. Infant growth parameters at birth (weight, head circumference, and length) were analyzed along with maternal risk factors known to be associated with changes in fetal growth, including maternal age, race, diagnosis of preeclampsia, gestational diabetes, and maternal use of alcohol or tobacco or substance abuse during pregnancy.

RESULTS

The incidence of hypospadias in the NICU population increased 10-fold from 0.4% in 1987 to 4% in the first quarter of 2000. Hypospadias was significantly more common in infants who had uniformly poor intrauterine growth (<10th percentiles) in the various parameters measured: birth weight, length, or head circumference. There were no significant differences in maternal age or race, nor were there differences in the use of alcohol, tobacco, or street drugs by the mother. There were no differences between singletons and multiple-gestation births. However, the frequency of occurrence was significantly higher among first-born infants (1.9%) compared with all other infants (0.9%).

CONCLUSIONS

The incidence of hypospadias in our NICU population has increased 10-fold during the 13-year period of study. There was a significant association of hypospadias with poor intrauterine growth. The growth restriction was probably of early gestational cause as there was proportionate involvement of somatic (weight and length) and brain growth (head circumference). The increasing frequency of hypospadias and its association with poor intrauterine growth originating in early gestation suggests that common environmental factor(s) that have an impact on both conditions may be involved.

[Pathologic horseshoe kidney. Report of 13 cases]

The authors report a series of 13 horseshoe kidneys observed over a 22-year period. All patients are men with a mean age of 39 years (20-65 years). The clinical features were dominated by abdomino-lumbar pain (nine cases). The horseshoe kidney was associated with renal stones in nine cases, uretero-pelvic junction syndrome in five cases and pyonephrosis in one case. The specific anatomic and surgical features of this rare malformation are emphasized and the therapeutic features of each uropathy associated with horseshoe kidney are discussed.

The search for congenital malformations in newborns with fetal cocaine exposure

CONTEXT

The association between prenatal cocaine exposure and congenital anomalies is not definitive.

OBJECTIVE

To determine whether prenatal cocaine exposure results in an increased number or identifiable pattern of abnormalities.

DESIGN

A prospective, longitudinal cohort enrolled between 1991 and 1993.

SETTING

Rural public health population delivering at a regional tertiary medical center.

PATIENTS

Two hundred seventy-two offspring of 154 prenatally identified crack/cocaine users and 154 nonusing controls were matched on race, parity, location of prenatal care (that related to level of pregnancy risk), and socioeconomic status. Drug use was determined through repeated in-depth histories and urine screens. Infants not examined within 7 days of birth were excluded.

OUTCOME MEASURES

Assessments were made by experienced examiners masked to maternal drug history. Included were 16 anthropometric measurements and a checklist of 180 physical features defined and agreed upon in advance.

RESULTS

There were no differences on major risk variables between the included and excluded infants. There were significantly more premature infants in the cocaine-exposed group. Cocaine-exposed infants were significantly smaller in birth weight, length, and head circumference but did not differ on remaining anthropometric measurements. There was no difference in type or number of abnormalities identified between the exposed and nonexposed groups. There was no relationship between amount or timing of exposure and any of the outcomes.

CONCLUSIONS

This prospective, large-scale, blinded, systematic evaluation for congenital anomalies in prenatally cocaine-exposed children did not identify an increased number or consistent pattern of abnormalities.

Effect of cocaine on fetal kidney and bladder function

OBJECTIVE

To study the relationship between the bladder cycle and urine output by the fetus and the effect of intrauterine exposure to cocaine on both.

METHODS

Fetal hourly urine production rate and bladder cycle length were measured in two groups of pregnant women between 20 and 40 weeks of gestation. A control group of 59 normal pregnancies were examined longitudinally to establish reference ranges. A study group of 36 women with a history of cocaine abuse; urine was positive for cocaine only. They were examined once. The diameters of fetal bladder were measured to calculate bladder volume and hourly urine output. The bladder cycle was the time interval between two successive acts of voiding by the fetus.

RESULTS

In the normal group, fetal hourly urine production had a positive linear correlation with the gestational age, with mean urine volume of 3.38 ml/h at 20 weeks and 48.36 ml/h at 40 weeks. The bladder cycle also had positive linear association with the advancing gestational age, with 26+/-4.76 min at 20 weeks and 65.2+/-14.85 min at 40 weeks. When compared with the corresponding gestational ages, the cocaine-exposed group showed a significant decrease (P < 0.0001) in the hourly urine production and the bladder cycle. There was significant correlation (r = 0.95, P < 0.001) between bladder cycle and hourly urine output in the control group, but not in the cocaine group.

CONCLUSION

Cocaine decreases fetal urine output and bladder cycle.

Peripartum cocaine use and adverse pregnancy outcome

The objective of the study was to analyze possible adverse effects of peripartum cocaine use on maternal and fetal outcomes. Informed consent was given by 720 (97%) of 740 women who delivered consecutively at a large urban public hospital to test an umbilical cord blood sample for the presence of non-medically administered drugs of abuse and alcohol and to be interviewed for the study. Samples were tested for the presence of a cocaine metabolite (benzoylecgonine-BZE) by radioimmunoassay. The presence of other substances of abuse (alcohol, methamphetamine, opiates) resulted in exclusion from the sample of 143 subjects. Thus, in this cohort analysis, drug-free controls (N = 469) were compared to those positive for cocaine only (N = 108). Peripartum exposure to cocaine only, and no other substances of abuse, was associated with an increased frequency of abruptio placentae (1.9% vs 0% for control, P < 0.004), thick meconium stained amniotic fluid (3.9% vs 0.7% for controls, P < 0.006), premature rupture of membranes (P < 0.02), genitourinary anomalies (OR = 3.6, P < 0.05), abdominal wall defects (OR = 4.4, P < 0.01) and increased frequency of low birth weight (OR = 2.0, P < 0.02). These are important findings because previous studies have been complicated by the confounding effects of other substances of abuse. Am. J. Hum. Biol. 11:598-602, 1999. Copyright 1999 Wiley-Liss, Inc.