Teratology最新文献

Background: A female fetus with massive truncal-limb hydrops and large, loculated, nuchal hygromas in midgestation is highly likely to have Turner syndrome. This phenotype is recognized to be usually lethal, with only more mildly affected fetuses surviving to term birth.

Methods: The morphology and morphometrics of 117 midgestation fetuses with phenotypic Turner syndrome were analyzed.

Results: More than 90% of fetuses with phenotypic Turner syndrome were found to have heart weights below the 2.5 centile, as well as lung hypoplasia and restricted limb growth for brain weight standards, although brain weight was only mildly reduced for gestational age. In contrast, subnormal heart weight was much less common among fetuses with other etiologies of hydrops, hygromas, or pleural effusions.

Conclusions: We hypothesize that myocardial hypoplasia is a primary defect in Turner syndrome, and it leads to or is a major contributor to the phenotypic features that end in midgestational death.

Background: Fetal aminopterin/methotrexate syndrome was described nearly 50 years ago when these agents were first used as abortifacients. Physicians essentially stopped using these agents when the associated anomalies were recognized. Over the last several years the use of methotrexate with or without misoprostol for management of ectopic pregnancy and medical terminations of pregnancy has increased.

Methods: A 23-year-old female sought a termination at eight weeks gestation. She was given methotrexate followed by misoprostol.

Results: The medical termination was unsuccessful. The patient elected to continue the pregnancy secondary to financial considerations. She presented at 39 weeks without intervening prenatal care. She was diagnosed with severe preeclampsia. At delivery the infant was hypotonic and growth restricted with multiple anomalies.

Conclusions: Physicians are increasingly using methotrexate with or without misoprostol for treatment of ectopic pregnancies and medical terminations. Clinicians need to be aware of the characteristic teratologic effects of these two agents.

Background: Talipes equinovarus (TEV), also called congenital idiopathic clubfoot, true clubfoot and common clubfoot, is one of the most common major birth defects. Its correction is often difficult and expensive. Its etiology is poorly understood and few analytic epidemiological studies have been devoted to exploring specific risk factors for TEV.

Methods: Our population-based study consists of 239 documented cases of idiopathic TEV obtained from hospital and outpatient sources and 365 controls identified via random digit dialing from five Western Washington counties. Structured maternal interviews were conducted by trained interviewers and multiple logistic regression used to evaluate associations between maternal smoking and birth of a child with TEV.

Results: Our study shows strong associations between maternal smoking and idiopathic TEV. Case mothers were more likely to have smoked during pregnancy (OR = 2.2; 95% CI = 1.5, 3.3). Increased TEV risk was seen with increased smoking and estimates ranged from 1.5 for the lightest smokers to 3.9 for the heaviest smokers. Gender specific differences in risk were also noted with risk estimates of 1.8 (95% CI = 1.2, 3.0) for boys whose mothers smoked during pregnancy and 2.8 (95% CI = 1.4, 5.4) for girls. Trends for increased risk with higher numbers of cigarettes were noted for both genders. For isolated TEV, the overall odds ratio (OR) for smoking was 2.4 (95% CI = 1.6, 3.6) with a range from 1.4-4.6. No confounders were noted.

Conclusions: As postulated, maternal smoking during pregnancy appears to increase the risk of having a child with idiopathic clubfoot and the number of cigarettes smoked influence that risk. Further delineation of dose-response is warranted as are continued efforts to decrease maternal smoking during pregnancy.

Background: Nonsyndromic orofacial clefts have an estimated incidence of 1/1000 live births. Population genetic and embryologic studies suggest that cleft palate only (CPO) may be a distinct clinical entity from cleft lip with or without cleft palate (CL/P). Both CPO and CL/P are thought to be multifactorial in etiology, with evidence indicating that genetic, environmental, and developmental determinants may all play a role. The ARNT2 gene localizes to a conserved linkage group on mouse chromosome 7 that is syntenic with human chromosome 15q23-25. This chromosomal region was previously identified as a teratogen-induced clefting susceptibility locus in a genome-wide scan of AXB and BXA recombinant inbred mice. Arnt2 is expressed in the first branchial arch in mice. The teratogen 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) acts through the aryl hydrocarbon receptor (Ahr) pathway to produce dose-dependent CPO and thymic wasting in mice exposed in utero. Arnt2 and Ahr proteins dimerize in vitro. TCDD exposure is also associated with orofacial clefting in children of parents involved in agricultural work.

Methods: To determine whether ARNT2 influences human craniofacial development, we identified the human ARNT2 gene and conducted genomic structural analysis. Mutational screening was performed in infants with nonsyndromic CPO or CL/P who were identified by the Iowa Birth Defects Registry.

Results: A common amino acid polymorphism was detected but, no obvious disease-causing mutations were detected by SSCP analysis. The microsatellite marker, GATA89D04 (D15S823) was identified within intron 11 of the human ARNT2 gene, and linkage disequilibrium of nonsyndromic CPO and CL/P parent-infant trios was conducted.

Conclusions: No association was demonstrated with CPO (n = 45) and CL/P (n = 37). Teratology 66:85-90, 2002.